All-solid-state lithium-metal batteries(ASSLMBs)are widely considered as the ultimately advanced lithium batteries owing to their improved energy density and enhanced safety features.Among various solid electrolytes,s...All-solid-state lithium-metal batteries(ASSLMBs)are widely considered as the ultimately advanced lithium batteries owing to their improved energy density and enhanced safety features.Among various solid electrolytes,sulfide solid electrolyte(SSE)Li_(6)PS_(5)Cl has garnered significant attention.However,its application is limited by its poor cyclability and low critical current density(CCD).In this study,we introduce a novel approach to enhance the performance of Li_(6)PS_(5)Cl by doping it with fluorine,using lithium fluoride nanoparticles(LiFs)as the doping precursor.The F-doped electrolyte Li_(6)PS_(5)Cl-0.2LiF(nano)shows a doubled CCD,from 0.5 to 1.0 mA/cm^(2) without compromising the ionic conductivity;in fact,conductivity is enhanced from 2.82 to 3.30 mS/cm,contrary to the typical performance decline seen in conventionally doped Li_(6)PS_(5)Cl electrolytes.In symmetric Li|SSE|Li cells,the lifetime of Li_(6)PS_(5)Cl-0.2LiF(nano)is 4 times longer than that of Li_(6)PS_(5)Cl,achieving 1500 h vs.371 h under a charging/discharging current density of 0.2 mA/cm^(2).In Li|SSE|LiNbO_(3)@NCM721 full cells,which are tested under a cycling rate of 0.1 C at 30℃,the lifetime of Li_(6)PS_(5)Cl-0.2LiF(nano)is four times that of Li_(6)PS_(5)Cl,reaching 100 cycles vs.26 cycles.Therefore,the doping of nano-LiF off ers a promising approach to developing high-performance Li_(6)PS_(5)Cl for ASSLMBs.展开更多
Two zero-phonon lines with wide linewidth on R_(1)^(- ) and unknown colour centres have been observed in the magnesium-doped lithium fluoride crystals coloured by electron beam bombardment at 200 K in the measured tem...Two zero-phonon lines with wide linewidth on R_(1)^(- ) and unknown colour centres have been observed in the magnesium-doped lithium fluoride crystals coloured by electron beam bombardment at 200 K in the measured temperature range of 10-77 K. The R_(1)^(- )zero-phonon line can be nearly completely bleached using the normal spectrophotometer light at 10K. An obvious spectral burning hole in the absorption profile of the R_(1)^(- ) zero-phonon line of colour centres in the coloured lithium fluoride crystals has been obtained by using the spectrophotometer light adjusted to narrower bandwidth at 10K. The optical bleaching of the zero-phonon line can be partially recovered by annealing the crystals to room temperature for a short time period or irradiating the crystals with ultraviolet light above 40 K, and nearly complete restoration can be obtained after the ultraviolet light irradiation and storage in the dark for a long time at room temperature.展开更多
Iron-substituted cobalt-free lithium-rich manganese-based materials,with advantages of high specific capacity,high safety,and low cost,have been considered as the potential cathodes for lithium ion batteries.However,c...Iron-substituted cobalt-free lithium-rich manganese-based materials,with advantages of high specific capacity,high safety,and low cost,have been considered as the potential cathodes for lithium ion batteries.However,challenges,such as poor cycle stability and fast voltage fade during cycling under high potential,hinder these materials from commercialization.Here,we developed a method to directly coat LiF on the particle surface of Li_(1.2)Ni_(0.15)Fe_(0.1)Mn_(0.55O2).A uniform and flat film was successfully formed with a thickness about 3 nm,which can effect-ively protect the cathode material from irreversible phase transition during the deintercalation of Li^(+).After surface coating with 0.5wt%LiF,the cycling stability of Li_(1.2)Ni_(0.15)Fe_(0.1)Mn_(0.55O2) cycled at high potential was significantly improved and the voltage fade was largely suppressed.展开更多
Barium lithium fluoride nanocrystals were synthesized in cetyltrimethylammonium bromide (CTAB)/ 2-octanol/ water microemulsion systems. The impurity peaks in XRD patterns were not determined. The result of SEM confi...Barium lithium fluoride nanocrystals were synthesized in cetyltrimethylammonium bromide (CTAB)/ 2-octanol/ water microemulsion systems. The impurity peaks in XRD patterns were not determined. The result of SEM confirmed that the average sizes and shape of the BaLiF3 nanocrystals. The formation of BaLiF3 and particles size were strongly affected by water content. With increasing water content and reaction times, the size of the particle increases. Meanwhile, the solvent was also found to play a key role in the synthesis of the BaLiF3 nanocrystals.展开更多
Non-stoichiometric compound fluoride-doped LiFePO4/C cathode materials were synthesized via solid-state reaction using MgF2 and AlF3 as dopant. The fluoride-doped LiFePO4/C samples were characterized by X-ray diffract...Non-stoichiometric compound fluoride-doped LiFePO4/C cathode materials were synthesized via solid-state reaction using MgF2 and AlF3 as dopant. The fluoride-doped LiFePO4/C samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electrochemical testing. The results show that the materials are well crystallized and fluoride doping cannot change the space structure of LiFePO4. Slight amounts of Fe2O3 with no fluoride impurity were detected. Charge-discharge curves show that fluoride-doped samples have higher capacity at low rates compared with undoped LiFePO4/C. AlF3-doped samples have highest capacity at high discharge current. Both doped samples have larger polarization voltage than undoped samples. All samples exhibit good cycle stability.展开更多
Lithium metal is supposed to be critical material for constructing next-generation batteries due to extremely high capacity and ultralow redox potential. However, the perplexing issue of lithium dendrite growth impede...Lithium metal is supposed to be critical material for constructing next-generation batteries due to extremely high capacity and ultralow redox potential. However, the perplexing issue of lithium dendrite growth impedes the commercial application. The initial nucleation and low Li ions diffusion rate in the electrolyte/electrode interface dominate the deposition behavior. Therefore, a uniform and flexible interface is urgently needed. Here, a facile method is proposed to prepare a thin and porous LiF-rich layer (TPL) by the in-situ reaction of small amount of ammonium hydrogen difluoride (NH4HF2) and Li metal. The deposition morphology on Li metal anode with LiF layer is significantly flat and homogeneous owning to low lateral diffusion barrier on LiF crystals and the porous structure of TPL film. Additionally, the symmetrical cells made with such TPL Li anodes show significantly stable cycling over 100 cycles at high current density of 6 mA/cm^2. The TPL Li|LiFePO4 full cells keep over 99% capacity retention after 100 cycles at 2.0 C. This approach serves as a facile and controllable way of adjusting the protective layer on Li metal.展开更多
The high energy density and stability of solid-state lithium metal batteries(SSLMBs)have garnered great attention.Garnet-type oxides,especially Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)(LLZTO),with high ionic conductivity,...The high energy density and stability of solid-state lithium metal batteries(SSLMBs)have garnered great attention.Garnet-type oxides,especially Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)(LLZTO),with high ionic conductivity,wide electrochemical window,and stability to Li metal anode,are promising solid-state electrolyte(SSEs)materials for SSLMBs.However,Li/LLZTO interface issues including high interface resistance,inhomogeneous Li deposition,and Li dendrite growth have hindered the practical application of SSLMBs.Herein,a multi-functional Li–SnF_(2) composite anode with Li,LiF,and Li-Sn alloy was specifically designed and prepared.The composite anode improves the wettability to LLZTO,constructing an intimate contact interface between it and LLZTO.Meanwhile,ionic/electronic conductive paths in situ formed at the interface can effectively uniform Li deposition and suppress Li dendrite.The solid-state symmetric cell exhibits low interface resistance(11Ω·cm^(2)) and high critical current density(1.3 mA·cm^(−2))at 25℃.The full SSLMB based on LiFePO_(4) or LiNi_(0.5)Co_(0.2)Mn_(0.3)O_(2) cathode also shows stable cycling performance and high rate capability.This work provides a new composite anode strategy for achieving high-energy density and high-safety SSLMBs.展开更多
The guided Li dendrite growth by carbon-modifying separator is believed to be an effective strategy for enhancing life of lithium metal batteries(LMBs).However,the weak adhesions,as well as the large interface impedan...The guided Li dendrite growth by carbon-modifying separator is believed to be an effective strategy for enhancing life of lithium metal batteries(LMBs).However,the weak adhesions,as well as the large interface impedance between the smooth separator and the carbon functional layer(CFL) lead to an easily peeling of the CFL after repetitive cycles.Herein,we propose a promising solution by an inserting thin buffer layer(TBL) to strengthen the adhesion between CFL and separator as a double modifying layer(C-TBL) of the LMBs separator,which greatly improves the stability of the CFL and provides an effective Li metal anode protection.Owing to the sufficient ionic conductivity,chemical stability and strong adhesion to the separator of the TBL,it can avoid the failure of the CFL functionality with small interface impedance.Moreover,the CFL effectively reduces localized flux of Li+ through its abundant pores.The Li/Li cell with C-TBL separator displays the Li dendrite-free and stable cycling performance for at least 1500 h.When LiFePO_(4)(LFP) is employed as the cathode electrode,the assembled full cell with C-TBL separator shows the excellent rate performance and outstanding cycling capability.Our study builds a stable Li+conducting "bridge" between the functional layer and the separator in stabilizing Li metal anode,and provides a fresh idea of the artificial separator of LMBs.展开更多
基金supported by the National Key Research and Development Program of China(No.2018YFE0111600)the Haihe Laboratory of Sustainable Chemical Transformations(No.CYZC202307)for financial support。
文摘All-solid-state lithium-metal batteries(ASSLMBs)are widely considered as the ultimately advanced lithium batteries owing to their improved energy density and enhanced safety features.Among various solid electrolytes,sulfide solid electrolyte(SSE)Li_(6)PS_(5)Cl has garnered significant attention.However,its application is limited by its poor cyclability and low critical current density(CCD).In this study,we introduce a novel approach to enhance the performance of Li_(6)PS_(5)Cl by doping it with fluorine,using lithium fluoride nanoparticles(LiFs)as the doping precursor.The F-doped electrolyte Li_(6)PS_(5)Cl-0.2LiF(nano)shows a doubled CCD,from 0.5 to 1.0 mA/cm^(2) without compromising the ionic conductivity;in fact,conductivity is enhanced from 2.82 to 3.30 mS/cm,contrary to the typical performance decline seen in conventionally doped Li_(6)PS_(5)Cl electrolytes.In symmetric Li|SSE|Li cells,the lifetime of Li_(6)PS_(5)Cl-0.2LiF(nano)is 4 times longer than that of Li_(6)PS_(5)Cl,achieving 1500 h vs.371 h under a charging/discharging current density of 0.2 mA/cm^(2).In Li|SSE|LiNbO_(3)@NCM721 full cells,which are tested under a cycling rate of 0.1 C at 30℃,the lifetime of Li_(6)PS_(5)Cl-0.2LiF(nano)is four times that of Li_(6)PS_(5)Cl,reaching 100 cycles vs.26 cycles.Therefore,the doping of nano-LiF off ers a promising approach to developing high-performance Li_(6)PS_(5)Cl for ASSLMBs.
基金Supported partially by the National Natural Science Foundation of China under Grant No.69178028。
文摘Two zero-phonon lines with wide linewidth on R_(1)^(- ) and unknown colour centres have been observed in the magnesium-doped lithium fluoride crystals coloured by electron beam bombardment at 200 K in the measured temperature range of 10-77 K. The R_(1)^(- )zero-phonon line can be nearly completely bleached using the normal spectrophotometer light at 10K. An obvious spectral burning hole in the absorption profile of the R_(1)^(- ) zero-phonon line of colour centres in the coloured lithium fluoride crystals has been obtained by using the spectrophotometer light adjusted to narrower bandwidth at 10K. The optical bleaching of the zero-phonon line can be partially recovered by annealing the crystals to room temperature for a short time period or irradiating the crystals with ultraviolet light above 40 K, and nearly complete restoration can be obtained after the ultraviolet light irradiation and storage in the dark for a long time at room temperature.
基金financially supported by the project of International Science&Technology Cooperation of China(No.2019YFE0100200)。
文摘Iron-substituted cobalt-free lithium-rich manganese-based materials,with advantages of high specific capacity,high safety,and low cost,have been considered as the potential cathodes for lithium ion batteries.However,challenges,such as poor cycle stability and fast voltage fade during cycling under high potential,hinder these materials from commercialization.Here,we developed a method to directly coat LiF on the particle surface of Li_(1.2)Ni_(0.15)Fe_(0.1)Mn_(0.55O2).A uniform and flat film was successfully formed with a thickness about 3 nm,which can effect-ively protect the cathode material from irreversible phase transition during the deintercalation of Li^(+).After surface coating with 0.5wt%LiF,the cycling stability of Li_(1.2)Ni_(0.15)Fe_(0.1)Mn_(0.55O2) cycled at high potential was significantly improved and the voltage fade was largely suppressed.
文摘Barium lithium fluoride nanocrystals were synthesized in cetyltrimethylammonium bromide (CTAB)/ 2-octanol/ water microemulsion systems. The impurity peaks in XRD patterns were not determined. The result of SEM confirmed that the average sizes and shape of the BaLiF3 nanocrystals. The formation of BaLiF3 and particles size were strongly affected by water content. With increasing water content and reaction times, the size of the particle increases. Meanwhile, the solvent was also found to play a key role in the synthesis of the BaLiF3 nanocrystals.
基金financially supported by the National High-Technology"863"Program of China(No.2008AA11A103)
文摘Non-stoichiometric compound fluoride-doped LiFePO4/C cathode materials were synthesized via solid-state reaction using MgF2 and AlF3 as dopant. The fluoride-doped LiFePO4/C samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electrochemical testing. The results show that the materials are well crystallized and fluoride doping cannot change the space structure of LiFePO4. Slight amounts of Fe2O3 with no fluoride impurity were detected. Charge-discharge curves show that fluoride-doped samples have higher capacity at low rates compared with undoped LiFePO4/C. AlF3-doped samples have highest capacity at high discharge current. Both doped samples have larger polarization voltage than undoped samples. All samples exhibit good cycle stability.
基金supported by the National Basic Research Program of China (Grant no. 2015CB251100)Beijing Natural Science Foundation (No. L182023)
文摘Lithium metal is supposed to be critical material for constructing next-generation batteries due to extremely high capacity and ultralow redox potential. However, the perplexing issue of lithium dendrite growth impedes the commercial application. The initial nucleation and low Li ions diffusion rate in the electrolyte/electrode interface dominate the deposition behavior. Therefore, a uniform and flexible interface is urgently needed. Here, a facile method is proposed to prepare a thin and porous LiF-rich layer (TPL) by the in-situ reaction of small amount of ammonium hydrogen difluoride (NH4HF2) and Li metal. The deposition morphology on Li metal anode with LiF layer is significantly flat and homogeneous owning to low lateral diffusion barrier on LiF crystals and the porous structure of TPL film. Additionally, the symmetrical cells made with such TPL Li anodes show significantly stable cycling over 100 cycles at high current density of 6 mA/cm^2. The TPL Li|LiFePO4 full cells keep over 99% capacity retention after 100 cycles at 2.0 C. This approach serves as a facile and controllable way of adjusting the protective layer on Li metal.
基金This study was financially supported by the National Natural Science Foundation of China(Nos.52177208,52171202,51971055 and 51871046)the National Safety Academic Fund(Nos.U1930208,U2030206 and U1730136).
文摘The high energy density and stability of solid-state lithium metal batteries(SSLMBs)have garnered great attention.Garnet-type oxides,especially Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)(LLZTO),with high ionic conductivity,wide electrochemical window,and stability to Li metal anode,are promising solid-state electrolyte(SSEs)materials for SSLMBs.However,Li/LLZTO interface issues including high interface resistance,inhomogeneous Li deposition,and Li dendrite growth have hindered the practical application of SSLMBs.Herein,a multi-functional Li–SnF_(2) composite anode with Li,LiF,and Li-Sn alloy was specifically designed and prepared.The composite anode improves the wettability to LLZTO,constructing an intimate contact interface between it and LLZTO.Meanwhile,ionic/electronic conductive paths in situ formed at the interface can effectively uniform Li deposition and suppress Li dendrite.The solid-state symmetric cell exhibits low interface resistance(11Ω·cm^(2)) and high critical current density(1.3 mA·cm^(−2))at 25℃.The full SSLMB based on LiFePO_(4) or LiNi_(0.5)Co_(0.2)Mn_(0.3)O_(2) cathode also shows stable cycling performance and high rate capability.This work provides a new composite anode strategy for achieving high-energy density and high-safety SSLMBs.
基金supported by the National Natural Science Foundation of China(Nos.21978110,21905110,and 51772126)the Jilin Province Science and Technology Department Program(Nos.20200201187JC,20200201236JC,20190201309JC,20190101009JH and 20180201079GX)+3 种基金the Fundamental Research Funds for the Central Universities(Jilin University,JLU)the “13th five-year” Science and Technology Project of Jilin Provincial Education Department(Nos.JJKH_(2)0200407KJ,JJKH_(2)0200411KJ and JJKH_(2)0191003KJ)the Jilin Province Development and Reform Commission Program(Nos.2020C026-3 and 2019C042-1)the Jilin Province Fund for Talent Development Program(No.[2019]874)。
文摘The guided Li dendrite growth by carbon-modifying separator is believed to be an effective strategy for enhancing life of lithium metal batteries(LMBs).However,the weak adhesions,as well as the large interface impedance between the smooth separator and the carbon functional layer(CFL) lead to an easily peeling of the CFL after repetitive cycles.Herein,we propose a promising solution by an inserting thin buffer layer(TBL) to strengthen the adhesion between CFL and separator as a double modifying layer(C-TBL) of the LMBs separator,which greatly improves the stability of the CFL and provides an effective Li metal anode protection.Owing to the sufficient ionic conductivity,chemical stability and strong adhesion to the separator of the TBL,it can avoid the failure of the CFL functionality with small interface impedance.Moreover,the CFL effectively reduces localized flux of Li+ through its abundant pores.The Li/Li cell with C-TBL separator displays the Li dendrite-free and stable cycling performance for at least 1500 h.When LiFePO_(4)(LFP) is employed as the cathode electrode,the assembled full cell with C-TBL separator shows the excellent rate performance and outstanding cycling capability.Our study builds a stable Li+conducting "bridge" between the functional layer and the separator in stabilizing Li metal anode,and provides a fresh idea of the artificial separator of LMBs.
