Although high salt concentration electrolyte(HCE)can construct effective Li F-rich interphase film and solve the interphasial instability issue of graphite anode,its high cost,high viscosity and poor wettability with ...Although high salt concentration electrolyte(HCE)can construct effective Li F-rich interphase film and solve the interphasial instability issue of graphite anode,its high cost,high viscosity and poor wettability with electrode materials limit its large-scale application.Generally,localized high concentration electrolyte(LHCE)is obtained by introducing an electrochemically inert diluent into HCE to avoid the above-mentioned problems while maintaining the high interphasial stability of HCE with graphite anode.Unlike traditional inert diluents,1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluropropyl ether(TTE)with electrochemical activity is introduced into propylene carbonate(PC)-based HCE to obtain LHCE-2(1 M LiPF_(6),PC:DMC:TTE=1:1:6.1)herein.Experimental and theoretical simulation results show that TTE participates in the oxidation decomposition and film-forming reaction at the NCM622 cathode surface,conducting a cathode electrolyte interphase(CEI)rich in organic fluorides with excellent electron insulation ability,high structural stability and low interphasial impedance.Thanks to the outstanding interphasial properties induced by LHCE-2,the graphite||NMC622 pouch cell reaches a capacity retention of 80%after 500 cycles at 1 C under room temperature.While at sub-zero temperatures,the capacity released by the cell with LHCE-2 electrolyte is significantly higher than that of HCE and conventional EC-based electrolytes.Meanwhile,the LHCE-2 electrolyte inherits the advantages of TTE flame-resistant,thus improving the safety of the battery.展开更多
Lithium–sulfur(Li–S)batteries are considered as highly promising energy storage devices because of their ultrahigh theoretical energy density of 2600 Wh kg^(-1).The highest practical energy density of Li–S batterie...Lithium–sulfur(Li–S)batteries are considered as highly promising energy storage devices because of their ultrahigh theoretical energy density of 2600 Wh kg^(-1).The highest practical energy density of Li–S batteries reported at pouch cell level has exceeded 500 Wh kg^(-1),which significantly surpasses that of lithium-ion batteries.Herein,a 700 Wh kg^(-1)-level Li–S pouch cell is successfully constructed.The pouch cell is designed at 6 Ah level with high-sulfur-loading cathodes of 7.4 mgScm^(-2),limited anode excess(50μm in thickness),and lean electrolyte(electrolyte to sulfur ratio of 1.7 gelectrolyteg^(-1)S).Accordingly,an ultrahigh specific capacity of 1563 m A h g^(-1)is achieved with the addition of a redox comediator to afford a practical energy density of 695 Wh kg^(-1)based on the total mass of all components.The pouch cell can operate stably for three cycles and then failed due to rapidly increased polarization at the second discharge plateau.According to failure analysis,electrolyte exhaustion is suggested as the key limiting factor.This work achieves a significant breakthrough in constructing high-energy-density Li–S batteries and propels the development of Li–S batteries toward practical working conditions.展开更多
Conventional lithium-ion batteries(LIBs)with liquid electrolytes are challenged by their big safety concerns,particularly used in electric vehicles.All-solid-state batteries using solid-state electrolytes have been pr...Conventional lithium-ion batteries(LIBs)with liquid electrolytes are challenged by their big safety concerns,particularly used in electric vehicles.All-solid-state batteries using solid-state electrolytes have been proposed to significantly improve safety yet are impeded by poor interfacial solid–solid contact and fast interface degradation.As a compromising strategy,in situ solidification has been proposed in recent years to fabricate quasi-solid-state batteries,which have great advantages in constructing intimate interfaces and cost-effective mass manufacturing.In this work,quasi-solid-state pouch cells with high loading electrodes(≥3 m Ah cm^(-2))were fabricated via in situ solidification of poly(ethylene glycol)diacrylate-based polymer electrolytes(PEGDA-PEs).Both single-layer and multilayer quasi-solid-state pouch cells(2.0 Ah)have demonstrated stable electrochemical performance over500 cycles.The superb electrochemical stability is closely related to the formation of robust and compatible interphase,which successfully inhibits interfacial side reactions and prevents interfacial structural degradation.This work demonstrates that in situ solidification is a facile and cost-effective approach to fabricate quasi-solid-state pouch cells with both excellent electrochemical performance and safety.展开更多
As the rapid development of more powerful and safer lithiumion batteries, the mechanism study of gases evolution is attacking more and more attention in recent years. Especially under overcharge/discharge and/or high-...As the rapid development of more powerful and safer lithiumion batteries, the mechanism study of gases evolution is attacking more and more attention in recent years. Especially under overcharge/discharge and/or high-temperature working condition.展开更多
Battery electrochemistry in an actual cell is a complicated behavior influenced by the current density,uniformity,and ion-diffusion distance,etc.The anisotropism of the lithiation/delithiation degree is usually inevit...Battery electrochemistry in an actual cell is a complicated behavior influenced by the current density,uniformity,and ion-diffusion distance,etc.The anisotropism of the lithiation/delithiation degree is usually inevitable,and even worse,due to a trend of big-size cell design,typically such as 4680 and blade cells,which accelerated a battery failure during repeat lithiation and delithiation of cathodes.Inspire by that,two big-size pouch cells with big sizes,herein,are selected to reveal the ion-diffusion dependency of the cathodes at different locations.Interestingly,we find that the LiCoO_(2) pouch cell exhibits ~5 A h loss after 120 charge-discharge cycles,but a 15 A h loss is verified in a LiNixMnyCO_(1-x)-yO_(2)(NCM) cell.Synchrotron-based imaging analysis indicates that higher ion-diffusion rates in the LiCoO_(2)than that in the LiNixMnyCO_(1-x)-yO_(2)is the determined factor for the anisotropic cathode fading,which is responsible for a severe mechanical issue of particle damage,such as cracks and even pulverization,in the cathode materials.Meanwhile,we verify the different locations at the near-tab and bottom of the electrode make it worse due to the ion-diffusion kinetics and temperature,inducing a spatially uneven electrochemistry in the big-size pouch cell.The findings give an in-depth insight into pouch cell failure and make a guideline for high-energy cell design and development.展开更多
The uniformity of current density distribution upon electrodes is one of the most important factors determining the lithium dendrites growth and cycling performance of lithium metal batteries(LMBs). Herein,current den...The uniformity of current density distribution upon electrodes is one of the most important factors determining the lithium dendrites growth and cycling performance of lithium metal batteries(LMBs). Herein,current density distributions of lithium metal anodes induced by various engineering factors, consisting of uneven cathode, electrolyte distribution, and different tab positions, and their effects on the electrochemical performance are investigated theoretically and experimentally in pouch cells. The deviation of current density in lithium metal anodes ranges from 2.47% to 196.18% due to the different levels of uneven cathode materials. However, the deviation is just 13.60% for different electrolyte thicknesses between cathodes and anodes, even a ten-layer separator in some positions. The maximum deviation for variational tab positions is only 0.17%. The nonuniformity in current density distribution results in severe dendrite growth issues and poor electrochemical performance of LMBs. This work not only confirms the direct correlation between the uneven current density distribution and lithium deposition behaviors, but also points out the decisive effects of cathode surface roughness on current distribution of anodes, to which more attentions should be paid in practical applications of LMBs.展开更多
Lithium–sulfur(Li–S)batteries are highly regarded as next-generation energy storage devices due to their ultrahigh theoretical energy density of 2600 Wh kg^(−1).However,practical high-energy-density Li–S pouch cell...Lithium–sulfur(Li–S)batteries are highly regarded as next-generation energy storage devices due to their ultrahigh theoretical energy density of 2600 Wh kg^(−1).However,practical high-energy-density Li–S pouch cells suffer from limited cycling lifespan with rapid loss of active materials.Herein,systematic evaluation on a 400 Wh kg^(−1)Li–S pouch cell is carried out to reveal the working and failure mechanism of Li–S batteries under practical conditions.Electrode morphology,spatial distribution and species analysis of sulfur,and capacity retention of electrodes are respectively evaluated after the first cycle of discharge or charge.Considerable lithium polysulfides are found in electrolyte even at the end of discharge or charge,where the sulfur redox reactions are reversible with high capacity retention.Meanwhile,severe morphology change is identified on lithium metal anode,yet there remains substantial active lithium to support the following cycles.This work not only demonstrates unique behaviors of Li–S batteries under practical conditions,which is essential for promoting the progress of Li–S pouch cells,but also affords a systematic evaluation methodology to guide further investigation on high-energy-density Li–S batteries.展开更多
To meet the requirements of electronic vehicles(EVs) and hybrid electric vehicles(HEVs),the high energy density Li Ni_(0.8) Co_(0.15) Al_(0.05) O_2(NCA) cathode and Si–C anode have attracted more attention.Here we re...To meet the requirements of electronic vehicles(EVs) and hybrid electric vehicles(HEVs),the high energy density Li Ni_(0.8) Co_(0.15) Al_(0.05) O_2(NCA) cathode and Si–C anode have attracted more attention.Here we report the thermal behaviors of NCA/Si–C pouch cell during the charge/discharge processes at different current densities.The total heat generations are derived from the surface temperature change during electrochemical Li+insertion/extraction in adiabatic surrounding.The reversible heat is determined by the entropic coefficients,which are related with open-circuit voltage at different temperatures; while the irreversible heat is determined by the internal resistance,which can be obtained via V–I characteristic,electrochemical impedance spectroscopy and hybrid pulse power characterization(HPPC).During the electrochemical process,the reversible heat contributes less than 10% to total heat generation; and the heat generated in charge process is less than that in discharge process.The results of thermal behaviors analyses are conducive to understanding the safety management and paving the way for building a reliable thermal model of high energy density lithium ion battery.展开更多
Lithium–sulfur(Li–S)batteries promise high-energy-density potential to exceed the commercialized lithiumion batteries but suffer from limited cycling lifespan due to the side reactions between lithium polysulfides(L...Lithium–sulfur(Li–S)batteries promise high-energy-density potential to exceed the commercialized lithiumion batteries but suffer from limited cycling lifespan due to the side reactions between lithium polysulfides(LiPSs)and Li metal anodes.Herein,a three-way electrolyte with ternary solvents is proposed to enable high-energy-density and long-cycling Li–S pouch cells.Concretely,ternary solvents composed of 1,2-dimethoxyethane,di-isopropyl sulfide,and 1,3,5-trioxane are employed to guarantee smooth cathode kinetics,inhibit the parasitic reactions,and construct a robust solid electrolyte interphase,respectively.The cycling lifespan of Li–S coin cells with 50μm Li anodes and 4.0 mg cm^(−2) sulfur cathodes is prolonged from88 to 222 cycles using the three-way electrolyte.Nano-heterogeneous solvation structure of LiPSs and organic-rich solid electrolyte interphase are identified to improve the cycling stability of Li metal anodes.Consequently,a 3.0 Ah-level Li–S pouch cell with the three-way electrolyte realizes a high energy density of 405 Wh kg^(−1) and undergoes 27 cycles.Thiswork affords a three-way electrolyte recipe for suppressing the side reactions of LiPSs and inspires rational electrolyte design for practical high-energy-density and long-cycling Li–S batteries.展开更多
Comprehensive analyses on thermal runaway mechanisms are critically vital to achieve the safe lithium-sulfur(Li-S)batteries.The reactions between dissolved higher-order polysulfides and Li metal were found to be the o...Comprehensive analyses on thermal runaway mechanisms are critically vital to achieve the safe lithium-sulfur(Li-S)batteries.The reactions between dissolved higher-order polysulfides and Li metal were found to be the origins for the thermal runaway of 1.0 Ah cycled Li-S pouch cells.16-cycle pouch cell indicates high safety,heating from 30 to 300 ℃ without thermal runaway,while 16-cycle pouch cell with additional electrolyte undergoes severe thermal runaway at 147.9 ℃,demonstrating the key roles of the electrolyte on the thermal safety of batteries.On the contrary,thermal runaway does not occur for 45-cycle pouch cell despite the addition of the electrolyte.It is found that the higher-order polysulfides(Li_(2)S_(x) ≥ 6)are discovered in 16-cycle electrolyte while the sulfur species in 45-cycle electrolyte are Li_(2)S_(x) ≤ 4.In addition,strong exothermic reactions are discovered between cycled Li and dissolved higher-order polysulfide(Li_(2)S_(6) and Li_(2)S_(8))at 153.0 ℃,driving the thermal runaway of cycled Li-S pouch cells.This work uncovers the potential safety risks of Li-S batteries and negative roles of the polysulfide shuttle for Li-S batteries from the safety view.展开更多
The lithium-sulfur(Li-S)technology is the most promising candidate for next-generation batteries due to its high theoretical specific energy and steady progress for applications requiring lightweight batteries such as...The lithium-sulfur(Li-S)technology is the most promising candidate for next-generation batteries due to its high theoretical specific energy and steady progress for applications requiring lightweight batteries such as aviation or heavy electric vehicles.For these applications,however,the rate capability of Li-S cells requires significant improvement.Advanced electrolyte formulations in Li-S batteries enable new pathways for cell development and adjustment of all components.However,their rate capability at pouch cell level is often neither evaluated nor compared to state of the art(SOTA)LiTFSI/dimethoxyethane/dioxolane(LITFSI:lithium-bis(trifluoromethylsulfonyl)imide)electrolyte.Herein,the combination of the sparingly polysulfide(PS)solvating hexylmethylether/1,2-dimethoxyethane(HME/DME)electrolyte and highly conductive carbon nanotube Buckypaper(CNT-BP)with low porosity was evaluated in both coin and pouch cells and compared to dimethoxyethane/dioxolane reference electrolyte.An advanced sulfur transfer melt infiltration was employed for cathode production with CNT-BP.The Li+ion coordination in the HME/DME electrolyte was investigated by nuclear magnetic resonance(NMR)and Raman spectroscopy.Additionally,ionic conductivity and viscosity was investigated for the pristine electrolyte and a polysulfide-statured solution.Both electrolytes,DME/DOL-1/1(DOL:1,3-dioxolane)and HME/DME-8/2,are then combined with CNT-BP and transferred to multi-layered pouch cells.This study reveals that the ionic conductivity of the electrolyte increases drastically over state of(dis)charge especially for DME/DOL electrolyte and lean electrolyte regime leading to a better rate capability for the sparingly polysulfide solvating electrolyte.The evaluation in prototype cells is an important step towards bespoke adaption of Li-S batteries for practical applications.展开更多
Nitriles as efficient electrolyte additives are widely used in high-voltage lithium-ion batteries.However,their working mechanisms are still mysterious,especially in practical high-voltage LiCoO_(2)pouch lithium-ion b...Nitriles as efficient electrolyte additives are widely used in high-voltage lithium-ion batteries.However,their working mechanisms are still mysterious,especially in practical high-voltage LiCoO_(2)pouch lithium-ion batteries.Herein,we adopt a tridentate ligandcontaining 1,3,6-hexanetricarbonitrile(HTCN)as an effective electrolyte additive to shed light on the mechanism of stabilizing high-voltage LiCoO_(2)cathode(4.5 V)through nitriles.The LiCoO_(2)/graphite pouch cells with the HTCN additive electrolyte possess superior cycling performance,90%retention of the initial capacity after 800 cycles at 25℃,and 72%retention after 500 cycles at 45℃,which is feasible for practical application.Such an excellent cycling performance can be attributed to the stable interface:The HTCN molecules with strong electron-donating ability participate in the construction of cathode-electrolyte interphase(CEI)through coordinating with Co ions,which suppresses the decomposition of electrolyte and improves the structural stability of LiCoO_(2)during cycling.In summary,the work recognizes a coordinating-based interphase-forming mechanism as an effective strategy to optimize the performance of high voltage LiCoO_(2)cathode with appropriate electrolyte additives for practical pouch batteries.展开更多
Promoting industry applications of high-energy Li metal batteries(LMBs)is of vital importance for accelerating the electrification and decarbonization of our society.Unfortunately,the time-dependent storage aging of A...Promoting industry applications of high-energy Li metal batteries(LMBs)is of vital importance for accelerating the electrification and decarbonization of our society.Unfortunately,the time-dependent storage aging of Ah-level Li metal pouch cells,a ubiquitous but crucial practical indicator,has not yet been revealed.Herein,we first report the storage behaviors and multilateral synergistic aging mechanism of Ah-level NCM811jjLi pouch cells during the 120-day long-term storage under various conditions.Contrary to the conventional belief of Li-ion batteries with graphite intercalation anodes,the significant available capacity loss of 32.8%on average originates from the major electrolyte-sensitive anode corrosion and partial superimposed cathode degradation,and the irreversible capacity loss of 13.3%is essentially attributed to the unrecoverable interface/structure deterioration of NCM with further hindrance of the aged Li.Moreover,principles of alleviating aging have been proposed.This work bridges academia and industry and enriches the fundamental epistemology of storage aging of LMBs,shedding light on realistic applications of high-energy batteries.展开更多
Li metal anodes have attracted tremendous attention in the last decade because of their high theoretical capacities and low electrochemical potentials.However,until now,there has only been limited success in improving...Li metal anodes have attracted tremendous attention in the last decade because of their high theoretical capacities and low electrochemical potentials.However,until now,there has only been limited success in improving the interfacial and structural stabilities and in realizing the highly controllable and large-scale fabrication of this emerging material;these limitations have posed great obstacles to further performing fundamental and applied studies in Li metal anodes.In this review,we focus on summarizing the existing challenges of Li metal anodes based on the leap from coin cells to pouch cells and on outlining typical methods for designing Li metal anodes on demand;we controllably engineer their surface protection layers and structure sizes by encapsulating structured Li metal inside a variety of synthetic protection layers.We aim to provide a comprehensive understanding and serve as a strategic guide for designing and fabricating practicable Li metal anodes for use in pouch batteries.Challenges and opportunities regarding this burgeoning field are critically evaluated at the end of this review.展开更多
Elevating the charge cut-off voltage beyond traditional 4.2 V is a commonly accepted technology to increase the energy density of Li-ion batteries(LIBs) but the risk of Li-dendrites and fire hazard increases as well. ...Elevating the charge cut-off voltage beyond traditional 4.2 V is a commonly accepted technology to increase the energy density of Li-ion batteries(LIBs) but the risk of Li-dendrites and fire hazard increases as well. The use of ambi-functional additive, which forms stable solid electrolyte interphase(SEI) simultaneously at both cathode and anode, is a key to enabling a dendrites-free and well-working high-voltage LIB. Herein, a novel ambi-functional additive, pentaerythritol disulfate(PEDS), at 1 wt% without any other additive is demonstrated. We show the feasibility and high impacts of PEDS in forming lithium sulfateincorporated robust SEI layers at NCM523 cathode and graphite anode in 1 Ah-level pouch cell under4.4 V, 25 °C and 0.1 C rate, which mitigates the high-voltage instability, metal-dissolution and cracks on NCM523 particles, and prevents Li-dendrites at graphite anode. Improved capacity retention of 83%after 300 cycles is thereby achieved, with respect to 69% with base electrolyte, offering a promising path toward the design of practical high-energy LIBs.展开更多
Developing an effective method to synthesize high-performance high-voltage LiCoO_(2) is essential for its industrialization in lithium batteries(LIBs).This work proposes a simple mass-produced strategy for the first t...Developing an effective method to synthesize high-performance high-voltage LiCoO_(2) is essential for its industrialization in lithium batteries(LIBs).This work proposes a simple mass-produced strategy for the first time,that is,negative temperature coefficient thermosensitive Pr_(6)O_(11) nanoparticles are uniformly modified on LiCoO_(2) to prepare LiCoO_(2)@Pr_(6)O_(11)(LCO@PrO)via a liquid-phase mixing combined with annealing method.Tested at 274 mA g−1,the modified LCO@PrO electrodes deliver excellent 4.5 V high-voltage cycling performance with capacity retention ratios of 90.8%and 80.5%at 25 and 60℃,being much larger than those of 22.8%and 63.2%for bare LCO electrodes.Several effective strategies were used to clearly unveil the performance enhancement mechanism induced by Pr_(6)O_(11) modification.It is discovered that Pr_(6)O_(11) can improve interface compatibility,exhibit improved conductivity at elevated temperature,thus enhance the Li^(+)diffusion kinetics,and suppress the phase transformation of LCO and its resulting mechanical stresses.The 450 mAh LCO@PrO‖graphite pouch cells show excellent LIB performance and improved thermal safety characteristics.Importantly,the energy density of such pouch cell was increased even by~42%at 5 C.This extremely convenient technology is feasible for producing high-energy density LIBs with negligible cost increase,undoubtedly providing important academic inspiration for industrialization.展开更多
Developing sulfur cathodes with high catalytic activity on accelerating the sluggish redox kinetics of lithium polysulfides(Li PSs) and unveiling their mechanisms are pivotal for advanced lithium–sulfur(Li–S)batteri...Developing sulfur cathodes with high catalytic activity on accelerating the sluggish redox kinetics of lithium polysulfides(Li PSs) and unveiling their mechanisms are pivotal for advanced lithium–sulfur(Li–S)batteries. Herein, MoS2 is verified to reduce the Gibbs free energy for rate-limiting step of sulfur reduction and the dissociation energy of lithium sulfide(Li2 S) for the first time employing theoretical calculations. The Mo S2 nanosheets coated on mesoporous hollow carbon spheres(MHCS) are then reasonably designed as a sulfur host for high-capacity and long-life Li–S battery, in which MHCS can guarantee the high sulfur loading and fast electron/ion transfer. It is revealed that the shuttle effect is efficiently inhibited because of the boosted conversion of Li PSs. As a result, the coin cell based on the MHCS@Mo S2-S cathode exhibits stable cycling performance maintaining 735.7 mAh g^(-1) after 500 cycles at 1.0 C. More importantly, the pouch cell employing the MHCS@Mo S2-S cathodes achieves high specific capacity of1353.2 m Ah g^(-1) and prominent cycle stability that remaining 960.0 m Ah g^(-1) with extraordinary capacity retention of 79.8% at 0.1 C after 170 cycles. Therefore, this work paves a new avenue for developing practical high specific energy and long-life pouch-type Li–S batteries.展开更多
The stability of lithium metal anodes essentially dictates the lifespan of high-energy-density lithium metal batteries.Lithium nitrate(LiNO_(3))is widely recognized as an effective additive to stabilize lithium metal ...The stability of lithium metal anodes essentially dictates the lifespan of high-energy-density lithium metal batteries.Lithium nitrate(LiNO_(3))is widely recognized as an effective additive to stabilize lithium metal anodes by forming LiN_(x)O_(y)-containing solid electrolyte interphase(SEI).However,its poor solubility in electrolytes,especially ester electrolytes,hinders its applications in lithium metal batteries.Herein,an organic nitrate,isosorbide nitrate(ISDN),is proposed to replace LiNO_(3).ISDNhas a high solubility of 3.3M in ester electrolytes due to the introduction of organic segments in the molecule.The decomposition of ISDN generates LiN_(x)O_(y)-rich SEI,enabling uniform lithium deposition.The lifespan of lithium metal batteries with ISDN significantly increases from 80 to 155 cycles under demanding conditions.Furthermore,a lithium metal pouch cell of 439Whkg^(−1) delivers 50 cycles.This work opens a new avenue to develop additives by molecular modifications for practical lithium metal batteries.展开更多
基金supported by the National Natural Science Foundation of China (No.21972049)the Guangdong-Hong KongMacao Greater Bay Area Exchange Programs of SCNU (2022)。
文摘Although high salt concentration electrolyte(HCE)can construct effective Li F-rich interphase film and solve the interphasial instability issue of graphite anode,its high cost,high viscosity and poor wettability with electrode materials limit its large-scale application.Generally,localized high concentration electrolyte(LHCE)is obtained by introducing an electrochemically inert diluent into HCE to avoid the above-mentioned problems while maintaining the high interphasial stability of HCE with graphite anode.Unlike traditional inert diluents,1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluropropyl ether(TTE)with electrochemical activity is introduced into propylene carbonate(PC)-based HCE to obtain LHCE-2(1 M LiPF_(6),PC:DMC:TTE=1:1:6.1)herein.Experimental and theoretical simulation results show that TTE participates in the oxidation decomposition and film-forming reaction at the NCM622 cathode surface,conducting a cathode electrolyte interphase(CEI)rich in organic fluorides with excellent electron insulation ability,high structural stability and low interphasial impedance.Thanks to the outstanding interphasial properties induced by LHCE-2,the graphite||NMC622 pouch cell reaches a capacity retention of 80%after 500 cycles at 1 C under room temperature.While at sub-zero temperatures,the capacity released by the cell with LHCE-2 electrolyte is significantly higher than that of HCE and conventional EC-based electrolytes.Meanwhile,the LHCE-2 electrolyte inherits the advantages of TTE flame-resistant,thus improving the safety of the battery.
基金supported by the National Key Research and Development Program(2021YFB2500300,2021YFB2400300)the Natural Scientific Foundation of China(22109007)+3 种基金the Beijing Natural Science Foundation(JQ20004)the Scientific and Technological Key Project of Shanxi Province(20191102003)the Beijing Institute of Technology Research Fund Program for Young Scholarsthe Tsinghua University Initiative Scientific Research Program。
文摘Lithium–sulfur(Li–S)batteries are considered as highly promising energy storage devices because of their ultrahigh theoretical energy density of 2600 Wh kg^(-1).The highest practical energy density of Li–S batteries reported at pouch cell level has exceeded 500 Wh kg^(-1),which significantly surpasses that of lithium-ion batteries.Herein,a 700 Wh kg^(-1)-level Li–S pouch cell is successfully constructed.The pouch cell is designed at 6 Ah level with high-sulfur-loading cathodes of 7.4 mgScm^(-2),limited anode excess(50μm in thickness),and lean electrolyte(electrolyte to sulfur ratio of 1.7 gelectrolyteg^(-1)S).Accordingly,an ultrahigh specific capacity of 1563 m A h g^(-1)is achieved with the addition of a redox comediator to afford a practical energy density of 695 Wh kg^(-1)based on the total mass of all components.The pouch cell can operate stably for three cycles and then failed due to rapidly increased polarization at the second discharge plateau.According to failure analysis,electrolyte exhaustion is suggested as the key limiting factor.This work achieves a significant breakthrough in constructing high-energy-density Li–S batteries and propels the development of Li–S batteries toward practical working conditions.
基金supported by the Natural Sciences and Engineering Research Council of Canada(NSERC),Canada Research Chair Program(CRC),Canada Foundation for Innovation(CFI),Ontario Research Fund(ORF),China Automotive Battery Research Institute Co.,Ltd.,Glabat Solid-State Battery Inc.,Canada Light Source(CLS)at the University of Saskatchewan,Interdisciplinary Development Initiatives(IDI)by Western University,and University of Western Ontariothe support from Mitacs Accelerate Program(IT13735)the funding support from Banting Postdoctoral Fel owship(BPF—180162)
文摘Conventional lithium-ion batteries(LIBs)with liquid electrolytes are challenged by their big safety concerns,particularly used in electric vehicles.All-solid-state batteries using solid-state electrolytes have been proposed to significantly improve safety yet are impeded by poor interfacial solid–solid contact and fast interface degradation.As a compromising strategy,in situ solidification has been proposed in recent years to fabricate quasi-solid-state batteries,which have great advantages in constructing intimate interfaces and cost-effective mass manufacturing.In this work,quasi-solid-state pouch cells with high loading electrodes(≥3 m Ah cm^(-2))were fabricated via in situ solidification of poly(ethylene glycol)diacrylate-based polymer electrolytes(PEGDA-PEs).Both single-layer and multilayer quasi-solid-state pouch cells(2.0 Ah)have demonstrated stable electrochemical performance over500 cycles.The superb electrochemical stability is closely related to the formation of robust and compatible interphase,which successfully inhibits interfacial side reactions and prevents interfacial structural degradation.This work demonstrates that in situ solidification is a facile and cost-effective approach to fabricate quasi-solid-state pouch cells with both excellent electrochemical performance and safety.
基金partially supported by the National Natural Science Foundation of China (grant no. 22021001, 22179111)the Ministry of Science and Technology of China (grant no. 2021YFA1201900)+3 种基金the Basic Research Program of Tan Kah Kee Innovation Laboratory (grant no. RD2021070401)the Principal Fund from Xiamen University (grant no. 20720210015)the Fundamental Research Funds for the Central Universities (grant no. 20720220010)the National Natural Science Foundation of China (grant no. 22202082)。
文摘As the rapid development of more powerful and safer lithiumion batteries, the mechanism study of gases evolution is attacking more and more attention in recent years. Especially under overcharge/discharge and/or high-temperature working condition.
基金supported by the Natural Science Foundation of Heilongjiang Province (LH2021E031)National Key Research and Development Program of China (2021YFB2011200)funds from Chongqing Research Institute of HIT。
文摘Battery electrochemistry in an actual cell is a complicated behavior influenced by the current density,uniformity,and ion-diffusion distance,etc.The anisotropism of the lithiation/delithiation degree is usually inevitable,and even worse,due to a trend of big-size cell design,typically such as 4680 and blade cells,which accelerated a battery failure during repeat lithiation and delithiation of cathodes.Inspire by that,two big-size pouch cells with big sizes,herein,are selected to reveal the ion-diffusion dependency of the cathodes at different locations.Interestingly,we find that the LiCoO_(2) pouch cell exhibits ~5 A h loss after 120 charge-discharge cycles,but a 15 A h loss is verified in a LiNixMnyCO_(1-x)-yO_(2)(NCM) cell.Synchrotron-based imaging analysis indicates that higher ion-diffusion rates in the LiCoO_(2)than that in the LiNixMnyCO_(1-x)-yO_(2)is the determined factor for the anisotropic cathode fading,which is responsible for a severe mechanical issue of particle damage,such as cracks and even pulverization,in the cathode materials.Meanwhile,we verify the different locations at the near-tab and bottom of the electrode make it worse due to the ion-diffusion kinetics and temperature,inducing a spatially uneven electrochemistry in the big-size pouch cell.The findings give an in-depth insight into pouch cell failure and make a guideline for high-energy cell design and development.
基金supported by the National Natural Science Foundation of China (22075029, 22179070, U1932220)。
文摘The uniformity of current density distribution upon electrodes is one of the most important factors determining the lithium dendrites growth and cycling performance of lithium metal batteries(LMBs). Herein,current density distributions of lithium metal anodes induced by various engineering factors, consisting of uneven cathode, electrolyte distribution, and different tab positions, and their effects on the electrochemical performance are investigated theoretically and experimentally in pouch cells. The deviation of current density in lithium metal anodes ranges from 2.47% to 196.18% due to the different levels of uneven cathode materials. However, the deviation is just 13.60% for different electrolyte thicknesses between cathodes and anodes, even a ten-layer separator in some positions. The maximum deviation for variational tab positions is only 0.17%. The nonuniformity in current density distribution results in severe dendrite growth issues and poor electrochemical performance of LMBs. This work not only confirms the direct correlation between the uneven current density distribution and lithium deposition behaviors, but also points out the decisive effects of cathode surface roughness on current distribution of anodes, to which more attentions should be paid in practical applications of LMBs.
基金supported by the Beijing Natural Science Foundation(JQ20004)National Natural Science Foundation of China(U1801257)the Scientific and Technological Key Project of Shanxi Province(20191102003)。
文摘Lithium–sulfur(Li–S)batteries are highly regarded as next-generation energy storage devices due to their ultrahigh theoretical energy density of 2600 Wh kg^(−1).However,practical high-energy-density Li–S pouch cells suffer from limited cycling lifespan with rapid loss of active materials.Herein,systematic evaluation on a 400 Wh kg^(−1)Li–S pouch cell is carried out to reveal the working and failure mechanism of Li–S batteries under practical conditions.Electrode morphology,spatial distribution and species analysis of sulfur,and capacity retention of electrodes are respectively evaluated after the first cycle of discharge or charge.Considerable lithium polysulfides are found in electrolyte even at the end of discharge or charge,where the sulfur redox reactions are reversible with high capacity retention.Meanwhile,severe morphology change is identified on lithium metal anode,yet there remains substantial active lithium to support the following cycles.This work not only demonstrates unique behaviors of Li–S batteries under practical conditions,which is essential for promoting the progress of Li–S pouch cells,but also affords a systematic evaluation methodology to guide further investigation on high-energy-density Li–S batteries.
基金supported by the National Key R&D Program of China:Trackling Key Technology for Development and Industrialization of Power Lithium Ion Battery with High Specific Energy (Grant No.2016YFB0100508)
文摘To meet the requirements of electronic vehicles(EVs) and hybrid electric vehicles(HEVs),the high energy density Li Ni_(0.8) Co_(0.15) Al_(0.05) O_2(NCA) cathode and Si–C anode have attracted more attention.Here we report the thermal behaviors of NCA/Si–C pouch cell during the charge/discharge processes at different current densities.The total heat generations are derived from the surface temperature change during electrochemical Li+insertion/extraction in adiabatic surrounding.The reversible heat is determined by the entropic coefficients,which are related with open-circuit voltage at different temperatures; while the irreversible heat is determined by the internal resistance,which can be obtained via V–I characteristic,electrochemical impedance spectroscopy and hybrid pulse power characterization(HPPC).During the electrochemical process,the reversible heat contributes less than 10% to total heat generation; and the heat generated in charge process is less than that in discharge process.The results of thermal behaviors analyses are conducive to understanding the safety management and paving the way for building a reliable thermal model of high energy density lithium ion battery.
基金Beijing Municipal Natural Science Foundation,Grant/Award Number:Z200011National Natural Science Foundation of China,Grant/Award Numbers:22061132002,22379013,T2322015+6 种基金Seed Fund of Shanxi Research Institute for Clean Energy,Grant/Award Number:SXKYJF015S&T Program of Hebei Province,Grant/Award Number:22344402DTsinghua-Jiangyin Innovation Special Fund(TJISF)Tsinghua-Toyota Joint Research FundInstitute of Strategic Research,Huawei Technologies Co.,Ltd.Ordos-Tsinghua Innovative&Collaborative Research Program in Carbon NeutralityNational Key Research and Development Program of China,Grant/Award Numbers:2021YFB2500300,2021YFB2400300。
文摘Lithium–sulfur(Li–S)batteries promise high-energy-density potential to exceed the commercialized lithiumion batteries but suffer from limited cycling lifespan due to the side reactions between lithium polysulfides(LiPSs)and Li metal anodes.Herein,a three-way electrolyte with ternary solvents is proposed to enable high-energy-density and long-cycling Li–S pouch cells.Concretely,ternary solvents composed of 1,2-dimethoxyethane,di-isopropyl sulfide,and 1,3,5-trioxane are employed to guarantee smooth cathode kinetics,inhibit the parasitic reactions,and construct a robust solid electrolyte interphase,respectively.The cycling lifespan of Li–S coin cells with 50μm Li anodes and 4.0 mg cm^(−2) sulfur cathodes is prolonged from88 to 222 cycles using the three-way electrolyte.Nano-heterogeneous solvation structure of LiPSs and organic-rich solid electrolyte interphase are identified to improve the cycling stability of Li metal anodes.Consequently,a 3.0 Ah-level Li–S pouch cell with the three-way electrolyte realizes a high energy density of 405 Wh kg^(−1) and undergoes 27 cycles.Thiswork affords a three-way electrolyte recipe for suppressing the side reactions of LiPSs and inspires rational electrolyte design for practical high-energy-density and long-cycling Li–S batteries.
基金supported by the National Key Research and Development Program(grant No.2021YFB2500300)National Natural Science Foundation of China(grant Nos.22179070,22075029,U1932220)+2 种基金Beijing Municipal Natural Science Foundation(grant No.Z200011)the Natural Science Foundation of Jiangsu Province(grant No.BK20220073)the Fundamental Research Funds for the Central Universities(grant No.2242022R10082).
文摘Comprehensive analyses on thermal runaway mechanisms are critically vital to achieve the safe lithium-sulfur(Li-S)batteries.The reactions between dissolved higher-order polysulfides and Li metal were found to be the origins for the thermal runaway of 1.0 Ah cycled Li-S pouch cells.16-cycle pouch cell indicates high safety,heating from 30 to 300 ℃ without thermal runaway,while 16-cycle pouch cell with additional electrolyte undergoes severe thermal runaway at 147.9 ℃,demonstrating the key roles of the electrolyte on the thermal safety of batteries.On the contrary,thermal runaway does not occur for 45-cycle pouch cell despite the addition of the electrolyte.It is found that the higher-order polysulfides(Li_(2)S_(x) ≥ 6)are discovered in 16-cycle electrolyte while the sulfur species in 45-cycle electrolyte are Li_(2)S_(x) ≤ 4.In addition,strong exothermic reactions are discovered between cycled Li and dissolved higher-order polysulfide(Li_(2)S_(6) and Li_(2)S_(8))at 153.0 ℃,driving the thermal runaway of cycled Li-S pouch cells.This work uncovers the potential safety risks of Li-S batteries and negative roles of the polysulfide shuttle for Li-S batteries from the safety view.
基金financed by the German Ministry of Education and Research(BMBF)in the project“HiPoLiS”(No.03XP0178A).
文摘The lithium-sulfur(Li-S)technology is the most promising candidate for next-generation batteries due to its high theoretical specific energy and steady progress for applications requiring lightweight batteries such as aviation or heavy electric vehicles.For these applications,however,the rate capability of Li-S cells requires significant improvement.Advanced electrolyte formulations in Li-S batteries enable new pathways for cell development and adjustment of all components.However,their rate capability at pouch cell level is often neither evaluated nor compared to state of the art(SOTA)LiTFSI/dimethoxyethane/dioxolane(LITFSI:lithium-bis(trifluoromethylsulfonyl)imide)electrolyte.Herein,the combination of the sparingly polysulfide(PS)solvating hexylmethylether/1,2-dimethoxyethane(HME/DME)electrolyte and highly conductive carbon nanotube Buckypaper(CNT-BP)with low porosity was evaluated in both coin and pouch cells and compared to dimethoxyethane/dioxolane reference electrolyte.An advanced sulfur transfer melt infiltration was employed for cathode production with CNT-BP.The Li+ion coordination in the HME/DME electrolyte was investigated by nuclear magnetic resonance(NMR)and Raman spectroscopy.Additionally,ionic conductivity and viscosity was investigated for the pristine electrolyte and a polysulfide-statured solution.Both electrolytes,DME/DOL-1/1(DOL:1,3-dioxolane)and HME/DME-8/2,are then combined with CNT-BP and transferred to multi-layered pouch cells.This study reveals that the ionic conductivity of the electrolyte increases drastically over state of(dis)charge especially for DME/DOL electrolyte and lean electrolyte regime leading to a better rate capability for the sparingly polysulfide solvating electrolyte.The evaluation in prototype cells is an important step towards bespoke adaption of Li-S batteries for practical applications.
基金supported by the National Key Research and Development Program of China(Nos.2017YFA0206700 and 2017YFA0402802)the National Natural Science Foundation of China(Nos.21776265 and 51902304)Anhui Provincial Natural Science Foundation(No.1908085ME122).
文摘Nitriles as efficient electrolyte additives are widely used in high-voltage lithium-ion batteries.However,their working mechanisms are still mysterious,especially in practical high-voltage LiCoO_(2)pouch lithium-ion batteries.Herein,we adopt a tridentate ligandcontaining 1,3,6-hexanetricarbonitrile(HTCN)as an effective electrolyte additive to shed light on the mechanism of stabilizing high-voltage LiCoO_(2)cathode(4.5 V)through nitriles.The LiCoO_(2)/graphite pouch cells with the HTCN additive electrolyte possess superior cycling performance,90%retention of the initial capacity after 800 cycles at 25℃,and 72%retention after 500 cycles at 45℃,which is feasible for practical application.Such an excellent cycling performance can be attributed to the stable interface:The HTCN molecules with strong electron-donating ability participate in the construction of cathode-electrolyte interphase(CEI)through coordinating with Co ions,which suppresses the decomposition of electrolyte and improves the structural stability of LiCoO_(2)during cycling.In summary,the work recognizes a coordinating-based interphase-forming mechanism as an effective strategy to optimize the performance of high voltage LiCoO_(2)cathode with appropriate electrolyte additives for practical pouch batteries.
基金National Natural Science Foundation of China,Grant/Award Numbers:51974256,52034011The Outstanding Young Scholars of Shaanxi,Grant/Award Number:2019JC-12+3 种基金The Natural Science Basic Research Plan in Shaanxi Province of China,Grant/Award Numbers:2019JLZ-01,2019JLM-29Fundamental Research Funds for the Central Universities,Grant/Award Numbers:3102021ZD0401,3102021TS0406,3102019JC005the Youth Innovation Team of Shaanxi UniversitiesND Basic Research Funds,Grant/Award Number:G2022WD。
文摘Promoting industry applications of high-energy Li metal batteries(LMBs)is of vital importance for accelerating the electrification and decarbonization of our society.Unfortunately,the time-dependent storage aging of Ah-level Li metal pouch cells,a ubiquitous but crucial practical indicator,has not yet been revealed.Herein,we first report the storage behaviors and multilateral synergistic aging mechanism of Ah-level NCM811jjLi pouch cells during the 120-day long-term storage under various conditions.Contrary to the conventional belief of Li-ion batteries with graphite intercalation anodes,the significant available capacity loss of 32.8%on average originates from the major electrolyte-sensitive anode corrosion and partial superimposed cathode degradation,and the irreversible capacity loss of 13.3%is essentially attributed to the unrecoverable interface/structure deterioration of NCM with further hindrance of the aged Li.Moreover,principles of alleviating aging have been proposed.This work bridges academia and industry and enriches the fundamental epistemology of storage aging of LMBs,shedding light on realistic applications of high-energy batteries.
基金supported by the National Natural Science Foundation of China(Nos.52071227,22109025)the Key Scientific Research Project in Shanxi Province(Grant No.201805D121003)+5 种基金the Special Found Projects for Central Government Guidance to Local Science and Technology Developmentthe Science and Technology Major Projects of Shanxi Province(20191102004)the Fundamental Research Program of Shanxi Province(202103021222006)the Natural Science Foundation of Shanxi Province(2019D111102)the Research Project Supported by Shanxi Scholarship Council of China(HGKY2019085)the Natural Science Foundation of Fujian Province,China(2021J05121).
文摘Li metal anodes have attracted tremendous attention in the last decade because of their high theoretical capacities and low electrochemical potentials.However,until now,there has only been limited success in improving the interfacial and structural stabilities and in realizing the highly controllable and large-scale fabrication of this emerging material;these limitations have posed great obstacles to further performing fundamental and applied studies in Li metal anodes.In this review,we focus on summarizing the existing challenges of Li metal anodes based on the leap from coin cells to pouch cells and on outlining typical methods for designing Li metal anodes on demand;we controllably engineer their surface protection layers and structure sizes by encapsulating structured Li metal inside a variety of synthetic protection layers.We aim to provide a comprehensive understanding and serve as a strategic guide for designing and fabricating practicable Li metal anodes for use in pouch batteries.Challenges and opportunities regarding this burgeoning field are critically evaluated at the end of this review.
基金supported by the Ministry of Trade,Industry&Energy (A0022-00725)National Research Foundation grant (No.2019R1A2C1084024 and 2021R1A2C2005764) funded by the Ministry of Science and ICT of Korea+2 种基金Chungnam National Universitysupported by the Nano Material Technology Development Program through the National Research Foundation of Koreafunded by the Ministry of Science and ICT of Korea (2009-0082580)。
文摘Elevating the charge cut-off voltage beyond traditional 4.2 V is a commonly accepted technology to increase the energy density of Li-ion batteries(LIBs) but the risk of Li-dendrites and fire hazard increases as well. The use of ambi-functional additive, which forms stable solid electrolyte interphase(SEI) simultaneously at both cathode and anode, is a key to enabling a dendrites-free and well-working high-voltage LIB. Herein, a novel ambi-functional additive, pentaerythritol disulfate(PEDS), at 1 wt% without any other additive is demonstrated. We show the feasibility and high impacts of PEDS in forming lithium sulfateincorporated robust SEI layers at NCM523 cathode and graphite anode in 1 Ah-level pouch cell under4.4 V, 25 °C and 0.1 C rate, which mitigates the high-voltage instability, metal-dissolution and cracks on NCM523 particles, and prevents Li-dendrites at graphite anode. Improved capacity retention of 83%after 300 cycles is thereby achieved, with respect to 69% with base electrolyte, offering a promising path toward the design of practical high-energy LIBs.
基金jointly supported by the Natural Science Foundations of China(Nos.22179020,12174057)Fujian Natural Science Foundation for Distinguished Young Scholars(Grant No.2020J06042)+2 种基金Foreign science and technology cooperation project of Fuzhou Science and Technology Bureau(No.2021-Y-086)Natural Science Foundation of Fujian Province(Grant No.2018J01660)Cultivation plan of outstanding young scientific research talents of Fujian Education Department(Grant No.J1-1323).
文摘Developing an effective method to synthesize high-performance high-voltage LiCoO_(2) is essential for its industrialization in lithium batteries(LIBs).This work proposes a simple mass-produced strategy for the first time,that is,negative temperature coefficient thermosensitive Pr_(6)O_(11) nanoparticles are uniformly modified on LiCoO_(2) to prepare LiCoO_(2)@Pr_(6)O_(11)(LCO@PrO)via a liquid-phase mixing combined with annealing method.Tested at 274 mA g−1,the modified LCO@PrO electrodes deliver excellent 4.5 V high-voltage cycling performance with capacity retention ratios of 90.8%and 80.5%at 25 and 60℃,being much larger than those of 22.8%and 63.2%for bare LCO electrodes.Several effective strategies were used to clearly unveil the performance enhancement mechanism induced by Pr_(6)O_(11) modification.It is discovered that Pr_(6)O_(11) can improve interface compatibility,exhibit improved conductivity at elevated temperature,thus enhance the Li^(+)diffusion kinetics,and suppress the phase transformation of LCO and its resulting mechanical stresses.The 450 mAh LCO@PrO‖graphite pouch cells show excellent LIB performance and improved thermal safety characteristics.Importantly,the energy density of such pouch cell was increased even by~42%at 5 C.This extremely convenient technology is feasible for producing high-energy density LIBs with negligible cost increase,undoubtedly providing important academic inspiration for industrialization.
基金supported by the funding from the Strategy Priority Research Program of Chinese Academy of Science (Grant No. XDA17020404)DICP&QIBEBT (DICP&QIBEBT UN201702)+8 种基金R&D Projects in Key Areas of Guangdong Province (2019B090908001)Science and Technology Innovation Foundation of Dalian (2018J11CY020)Defense Industrial Technology Development Program (JCKY2018130C107)National Natural Science Foundation of China (Grants 51872283)Liao Ning Revitalization Talents Program (Grant XLYC1807153)Natural Science Foundation of Liaoning Province (Grant 20180510038)DICP (DICP ZZBS201708, DICP ZZBS201802)DNL Cooperation FundCAS (DNL180310, DNL180308, DNL201912, and DNL201915)。
文摘Developing sulfur cathodes with high catalytic activity on accelerating the sluggish redox kinetics of lithium polysulfides(Li PSs) and unveiling their mechanisms are pivotal for advanced lithium–sulfur(Li–S)batteries. Herein, MoS2 is verified to reduce the Gibbs free energy for rate-limiting step of sulfur reduction and the dissociation energy of lithium sulfide(Li2 S) for the first time employing theoretical calculations. The Mo S2 nanosheets coated on mesoporous hollow carbon spheres(MHCS) are then reasonably designed as a sulfur host for high-capacity and long-life Li–S battery, in which MHCS can guarantee the high sulfur loading and fast electron/ion transfer. It is revealed that the shuttle effect is efficiently inhibited because of the boosted conversion of Li PSs. As a result, the coin cell based on the MHCS@Mo S2-S cathode exhibits stable cycling performance maintaining 735.7 mAh g^(-1) after 500 cycles at 1.0 C. More importantly, the pouch cell employing the MHCS@Mo S2-S cathodes achieves high specific capacity of1353.2 m Ah g^(-1) and prominent cycle stability that remaining 960.0 m Ah g^(-1) with extraordinary capacity retention of 79.8% at 0.1 C after 170 cycles. Therefore, this work paves a new avenue for developing practical high specific energy and long-life pouch-type Li–S batteries.
基金supported by the Key Research and Development Program of Yunnan Province(202103A A080019)S&T Program of Hebei(22344402D)+4 种基金National Key Research and Development Program(2021YFB2400300)National Natural Science Foundation of China(22108149)China Postdoctoral Science Foundation(2021M700404)Scientific and Technological Key Project of Shanxi Province(20191102003)Beijing Institute of Technology Research Fund Program for Young Scholars.
文摘The stability of lithium metal anodes essentially dictates the lifespan of high-energy-density lithium metal batteries.Lithium nitrate(LiNO_(3))is widely recognized as an effective additive to stabilize lithium metal anodes by forming LiN_(x)O_(y)-containing solid electrolyte interphase(SEI).However,its poor solubility in electrolytes,especially ester electrolytes,hinders its applications in lithium metal batteries.Herein,an organic nitrate,isosorbide nitrate(ISDN),is proposed to replace LiNO_(3).ISDNhas a high solubility of 3.3M in ester electrolytes due to the introduction of organic segments in the molecule.The decomposition of ISDN generates LiN_(x)O_(y)-rich SEI,enabling uniform lithium deposition.The lifespan of lithium metal batteries with ISDN significantly increases from 80 to 155 cycles under demanding conditions.Furthermore,a lithium metal pouch cell of 439Whkg^(−1) delivers 50 cycles.This work opens a new avenue to develop additives by molecular modifications for practical lithium metal batteries.