Thick electrodes can increase incorporation of active electrode materials by diminishing the proportion of inactive constituents,improving the overall energy density of batteries.However,thick electrodes fabricated us...Thick electrodes can increase incorporation of active electrode materials by diminishing the proportion of inactive constituents,improving the overall energy density of batteries.However,thick electrodes fabricated using the conventional slurry casting approach frequently exhibit an exacerbated accumulation of carbon additives and binders on their surfaces,invariably leading to compromised electrochemical properties.In this study,we introduce a designed conductive agent/binder composite synthesized from carbon nanotube and polytetrafluoroethylene.This agent/binder composite facilitates production of dry-process-prepared ultra-thick electrodes endowed with a three-dimensional and uniformly distributed percolative architecture,ensuring superior electronic conductivity and remarkable mechanical resilience.Using this approach,ultra-thick LiCoO_(2)(LCO) electrodes demonstrated superior cycling performance and rate capabilities,registering an impressive loading capacity of up to 101.4 mg/cm^(2),signifying a 242% increase in battery energy density.In another analytical endeavor,time-of-flight secondary ion mass spectroscopy was used to clarify the distribution of cathode electrolyte interphase(CEI) in cycled LCO electrodes.The results provide unprecedented evidence explaining the intricate correlation between CEI generation and carbon distribution,highlighting the intrinsic advantages of the proposed dry-process approach in fine-tu ning the CEI,with excellent cycling performance in batteries equipped with ultra-thick electrodes.展开更多
Electrochemical lithium extraction from salt lakes is an effective strategy for obtaining lithium at a low cost.Nevertheless,the elevated Mg:Li ratio and the presence of numerous coexisting ions in salt lake brines gi...Electrochemical lithium extraction from salt lakes is an effective strategy for obtaining lithium at a low cost.Nevertheless,the elevated Mg:Li ratio and the presence of numerous coexisting ions in salt lake brines give rise to challenges,such as prolonged lithium extraction periods,diminished lithium extraction efficiency,and considerable environmental pollution.In this work,Li FePO4(LFP)served as the electrode material for electrochemical lithium extraction.The conductive network in the LFP electrode was optimized by adjusting the type of conductive agent.This approach resulted in high lithium extraction efficiency and extended cycle life.When the single conductive agent of acetylene black(AB)or multiwalled carbon nanotubes(MWCNTs)was replaced with the mixed conductive agent of AB/MWCNTs,the average diffusion coefficient of Li+in the electrode increased from 2.35×10^(-9)or 1.77×10^(-9)to 4.21×10^(-9)cm^(2)·s^(-1).At the current density of 20 mA·g^(-1),the average lithium extraction capacity per gram of LFP electrode increased from 30.36 mg with the single conductive agent(AB)to 35.62 mg with the mixed conductive agent(AB/MWCNTs).When the mixed conductive agent was used,the capacity retention of the electrode after 30 cycles reached 82.9%,which was considerably higher than the capacity retention of 65.8%obtained when the single AB was utilized.Meanwhile,the electrode with mixed conductive agent of AB/MWCNTs provided good cycling performance.When the conductive agent content decreased or the loading capacity increased,the electrode containing the mixed conductive agent continued to show excellent electrochemical performance.Furthermore,a self-designed,highly efficient,continuous lithium extraction device was constructed.The electrode utilizing the AB/MWCNT mixed conductive agent maintained excellent adsorption capacity and cycling performance in this device.This work provides a new perspective for the electrochemical extraction of lithium using LFP electrodes.展开更多
In this study,the impact of morphology of conductive agent and anode material(Fe3O4)on lithium storage properties was throughly investigated.Granular and belt-like Fe3O4active materials were separately blended with tw...In this study,the impact of morphology of conductive agent and anode material(Fe3O4)on lithium storage properties was throughly investigated.Granular and belt-like Fe3O4active materials were separately blended with two kinds of conductive agents(i.e.,granular acetylene black and multi-walled carbon nanotube)as anodes in lithium-ion batteries(LIBs),respectively.It was found that the morphology of conductive agent is of utmost importance in determining LIBs storage properties.In contrast,not as the way we anticipated,the morphology of anode material merely plays a subordinate role in their electrochemical performances.Further,the morphology-matching principle of electrode materials was discussed so as to render their utilization more rational and effective in LIBs.展开更多
This paper proposed an optimal approach to disperse the composite conductive agent which is composed of carbon black(CB)and graphene(Gr)within lithium-ion battery(LIB)slurry with different mixing speeds and mixing tim...This paper proposed an optimal approach to disperse the composite conductive agent which is composed of carbon black(CB)and graphene(Gr)within lithium-ion battery(LIB)slurry with different mixing speeds and mixing times.The internal structures of LIB slurry are characterized by Electrochemical Impedance Spectroscopy,Scanning Electron Microscopy,and Raman experiment.Initially,a composite conductive solution is prepared by mixing the composite conductive agent with NMP solvent under the conditions of five different mixing speeds n_(1)(n_(1)=1000,1100,1200,1300,1400 rpm)in the case of mixing time t_(1)=10 min.Subsequently,LIB slurry is prepared by blending the composite conductive solution,LiCoO_(2)and PVDF-NMP solution under the conditions of five different mixing speeds n_(2)(n_(2)=1000±280,1100±280,1200±280,1300±280,1400±280 rpm)in the case of mixing time t_(2)=6 min.By analyzing the internal structure of different LIB slurries,it shows that in the case of n_(1)=n_(2)=1200 rpm,a conductive network structure is well formed within LIB slurry.Additionally,in order to determine the optimal time to prepare the composite conductive solution for LIB slurry,nine different t_(1)(t_(1)=0,10,20,30,40,50,60,70,80 min)are selected.By analyzing the internal structure of different LIB slurries,a well-formed conductive network structure and a uniformly distributed composite conductive agent are deduced in LIB slurry when t_(1)=50 min.Therefore,it can be concluded that the composite conductive agent composed of CB and Gr is able to be uniformly dispersed in LIB slurry by establishing a well-formed conductive network structure under the optimal mixing speed n_(1)=n_(2)=1200 rpm and the optimal mixing time t_(1)=50 min,t_(2)=6 min.This kind of the internal structure has the potential to be used to further analyze the dispersion characterizations of LIB slurry under different composite conductive agent and CB/Gr ratios with the aim of improving the final performance of LIB.展开更多
A conventional electrode composite for rechargeable zinc-ion batteries(ZIBs)includes a binder for strong adhesion between the electrode material and the current collector.However,the introduction of a binder leads to ...A conventional electrode composite for rechargeable zinc-ion batteries(ZIBs)includes a binder for strong adhesion between the electrode material and the current collector.However,the introduction of a binder leads to electrochemical inactivity and low electrical conductivity,resulting in the decay of the capacity and a low rate capability.We present a binder-and conducting agent-free VO_(2) composite electrode using in situ polymerization of dopamine on a flexible current collector of pyroprotein-based fibers.The as-fabricated composite electrode was used as a substrate for the direct growth of VO_(2) as a self-supported form on polydopamine-derived pyroprotein-based fibers(pp-fibers@VO_(2)(B)).It has a high conductivity and flexible nature as a current collector and moderate binding without conventional binders and conducting agents for the VO_(2)(B) cathode.In addition,their electrochemical mechanism was elucidated.Their energy storage is induced by Zn^(2+)/H^(+) coinsertion during discharging,which can be confirmed by the lattice expansion,the formation of by-products including Zn_(x)(OTf)_(y)(OH)_(2x−y)·nH_(2)O,and the reduction of V^(4+)to V^(3+).Furthermore,the assembled Zn//pp-fibers@VO_(2)(B) pouch cells have excellent flexibility and stable electrochemical performance under various bending states,showing application possibilities for portable and wearable power sources.展开更多
In order to solve the problem of poor conductivity of traditional LiFePO_(4)cathode binders,we developed sodium alginate-Congo red copolymers(SA-CR)as water-soluble electrically conductive and mechanically robust comp...In order to solve the problem of poor conductivity of traditional LiFePO_(4)cathode binders,we developed sodium alginate-Congo red copolymers(SA-CR)as water-soluble electrically conductive and mechanically robust composite binder.Unlike most other electrically conductive polymer binders,the procedure is straightforward and low-cost to prepare SA-CR binder.Various SA-CR copolymers were prepared with different degree of compounding of CR to investigate the effect of CR on the electrochemical and physical properties of the prepared electrodes.The copolymer whose composition was filled with a mixture of SA and CR at a 3:1 mass ratio showed the best cell performance,due to the well-balanced electrical conductivity and mechanical properties.It exhibited a specific capacity of 118.8 m Ah/g at the 100th cycle with 92.1%capacity retention,significantly better than the 108.5 m Ah/g of conventional acetylene black electrodes.CR as a conduction-promoting agent in water-soluble composite binder favors the formation of continuous and homogenous conducting bridges throughout the electrode and increases the compaction density of electrode by reducing the conducting agent content of acetylene black and thus the improvement of electrode performance is realized.展开更多
Sulfide-based all-solid-state batteries(ASSBs)exhibit unparalleled application value due to the high ionic conductivity and good processability of sulfide solid electrolytes(SSEs).Carbon-based conductive agents(CAs)are ...Sulfide-based all-solid-state batteries(ASSBs)exhibit unparalleled application value due to the high ionic conductivity and good processability of sulfide solid electrolytes(SSEs).Carbon-based conductive agents(CAs)are often used in the construction of electronic conductive networks to achieve rapid electron transfer.However,CAs accelerate the formation of decomposition products of SSEs,and their effects on sulfide-based ASSBs are not fully understood.Herein,the effect of CAs(super P,vaper-grown carbonfibers,and carbon nanotubes)on the performance of sulfide-based ASSBs is investigated under different cathode active materials mass loading(8 and 25 mg⋅cm^(-2)).The results show that under low mass loading,the side reaction between the CAs and the SSEs deteriorates the performance of the cell,while the charge transfer promotion caused by the addition of CAs is only manifested under high mass loading.Furthermore,the gradient design strategy(enrichment of CAs near the current collector side and depletion of CAs near the electrolyte side)is applied to maximize the benefits of CAs in electron transport and reduce the adverse effects of CAs.The charge carrier transport barrier inside the high mass loading electrode is significantly reduced through the regulation of electronic conductivity.Consequently,the optimized electrode achieves a high areal capacity of 5.6 mAh⋅cm^(-2)at high current density(1.25 mA⋅cm2,0.2℃)at 25℃with a capacity retention of 87.85%after 100 cycles.This work provides a promising way for the design of high-mass loading electrodes with practical application value.展开更多
基金supported by the National Key Research and Development Program of China,China(2019YFA0705102)the National Natural Science Foundation of China,China(22179144,22005332)。
文摘Thick electrodes can increase incorporation of active electrode materials by diminishing the proportion of inactive constituents,improving the overall energy density of batteries.However,thick electrodes fabricated using the conventional slurry casting approach frequently exhibit an exacerbated accumulation of carbon additives and binders on their surfaces,invariably leading to compromised electrochemical properties.In this study,we introduce a designed conductive agent/binder composite synthesized from carbon nanotube and polytetrafluoroethylene.This agent/binder composite facilitates production of dry-process-prepared ultra-thick electrodes endowed with a three-dimensional and uniformly distributed percolative architecture,ensuring superior electronic conductivity and remarkable mechanical resilience.Using this approach,ultra-thick LiCoO_(2)(LCO) electrodes demonstrated superior cycling performance and rate capabilities,registering an impressive loading capacity of up to 101.4 mg/cm^(2),signifying a 242% increase in battery energy density.In another analytical endeavor,time-of-flight secondary ion mass spectroscopy was used to clarify the distribution of cathode electrolyte interphase(CEI) in cycled LCO electrodes.The results provide unprecedented evidence explaining the intricate correlation between CEI generation and carbon distribution,highlighting the intrinsic advantages of the proposed dry-process approach in fine-tu ning the CEI,with excellent cycling performance in batteries equipped with ultra-thick electrodes.
基金financially supported by the National Natural Science Foundation of China(No.52072322)the Department of Science and Technology of Sichuan Province,China(Nos.23GJHZ0147,23ZDYF0262,2022YFG0294,and 2019-GH02-00052-HZ)。
文摘Electrochemical lithium extraction from salt lakes is an effective strategy for obtaining lithium at a low cost.Nevertheless,the elevated Mg:Li ratio and the presence of numerous coexisting ions in salt lake brines give rise to challenges,such as prolonged lithium extraction periods,diminished lithium extraction efficiency,and considerable environmental pollution.In this work,Li FePO4(LFP)served as the electrode material for electrochemical lithium extraction.The conductive network in the LFP electrode was optimized by adjusting the type of conductive agent.This approach resulted in high lithium extraction efficiency and extended cycle life.When the single conductive agent of acetylene black(AB)or multiwalled carbon nanotubes(MWCNTs)was replaced with the mixed conductive agent of AB/MWCNTs,the average diffusion coefficient of Li+in the electrode increased from 2.35×10^(-9)or 1.77×10^(-9)to 4.21×10^(-9)cm^(2)·s^(-1).At the current density of 20 mA·g^(-1),the average lithium extraction capacity per gram of LFP electrode increased from 30.36 mg with the single conductive agent(AB)to 35.62 mg with the mixed conductive agent(AB/MWCNTs).When the mixed conductive agent was used,the capacity retention of the electrode after 30 cycles reached 82.9%,which was considerably higher than the capacity retention of 65.8%obtained when the single AB was utilized.Meanwhile,the electrode with mixed conductive agent of AB/MWCNTs provided good cycling performance.When the conductive agent content decreased or the loading capacity increased,the electrode containing the mixed conductive agent continued to show excellent electrochemical performance.Furthermore,a self-designed,highly efficient,continuous lithium extraction device was constructed.The electrode utilizing the AB/MWCNT mixed conductive agent maintained excellent adsorption capacity and cycling performance in this device.This work provides a new perspective for the electrochemical extraction of lithium using LFP electrodes.
基金financial aid from the National Natural Science Foundation of China(NSFC No.51472133)
文摘In this study,the impact of morphology of conductive agent and anode material(Fe3O4)on lithium storage properties was throughly investigated.Granular and belt-like Fe3O4active materials were separately blended with two kinds of conductive agents(i.e.,granular acetylene black and multi-walled carbon nanotube)as anodes in lithium-ion batteries(LIBs),respectively.It was found that the morphology of conductive agent is of utmost importance in determining LIBs storage properties.In contrast,not as the way we anticipated,the morphology of anode material merely plays a subordinate role in their electrochemical performances.Further,the morphology-matching principle of electrode materials was discussed so as to render their utilization more rational and effective in LIBs.
基金the support from National Natural Science Foundation of China(grant No.52006176)the Ministry of Education's“Chunhui Plan”Collaborative Research project(grant No.202200491)the Key Research and Development Project of Shaanxi Province(grant No.2022kw-18).
文摘This paper proposed an optimal approach to disperse the composite conductive agent which is composed of carbon black(CB)and graphene(Gr)within lithium-ion battery(LIB)slurry with different mixing speeds and mixing times.The internal structures of LIB slurry are characterized by Electrochemical Impedance Spectroscopy,Scanning Electron Microscopy,and Raman experiment.Initially,a composite conductive solution is prepared by mixing the composite conductive agent with NMP solvent under the conditions of five different mixing speeds n_(1)(n_(1)=1000,1100,1200,1300,1400 rpm)in the case of mixing time t_(1)=10 min.Subsequently,LIB slurry is prepared by blending the composite conductive solution,LiCoO_(2)and PVDF-NMP solution under the conditions of five different mixing speeds n_(2)(n_(2)=1000±280,1100±280,1200±280,1300±280,1400±280 rpm)in the case of mixing time t_(2)=6 min.By analyzing the internal structure of different LIB slurries,it shows that in the case of n_(1)=n_(2)=1200 rpm,a conductive network structure is well formed within LIB slurry.Additionally,in order to determine the optimal time to prepare the composite conductive solution for LIB slurry,nine different t_(1)(t_(1)=0,10,20,30,40,50,60,70,80 min)are selected.By analyzing the internal structure of different LIB slurries,a well-formed conductive network structure and a uniformly distributed composite conductive agent are deduced in LIB slurry when t_(1)=50 min.Therefore,it can be concluded that the composite conductive agent composed of CB and Gr is able to be uniformly dispersed in LIB slurry by establishing a well-formed conductive network structure under the optimal mixing speed n_(1)=n_(2)=1200 rpm and the optimal mixing time t_(1)=50 min,t_(2)=6 min.This kind of the internal structure has the potential to be used to further analyze the dispersion characterizations of LIB slurry under different composite conductive agent and CB/Gr ratios with the aim of improving the final performance of LIB.
基金supported by“Regional Innovation Strategy (RIS)”through the National Research Foundation of Korea (NRF)funded by the Ministry of Education (MOE) (2021RIS-001)supported by National Research Foundation (NRF)funded by the Ministry of Science and Technology (NRF-2021R1F1A1064111)Ministry of Education (NRF-2017R1A6A1A06015181)of the Republic of Korea.
文摘A conventional electrode composite for rechargeable zinc-ion batteries(ZIBs)includes a binder for strong adhesion between the electrode material and the current collector.However,the introduction of a binder leads to electrochemical inactivity and low electrical conductivity,resulting in the decay of the capacity and a low rate capability.We present a binder-and conducting agent-free VO_(2) composite electrode using in situ polymerization of dopamine on a flexible current collector of pyroprotein-based fibers.The as-fabricated composite electrode was used as a substrate for the direct growth of VO_(2) as a self-supported form on polydopamine-derived pyroprotein-based fibers(pp-fibers@VO_(2)(B)).It has a high conductivity and flexible nature as a current collector and moderate binding without conventional binders and conducting agents for the VO_(2)(B) cathode.In addition,their electrochemical mechanism was elucidated.Their energy storage is induced by Zn^(2+)/H^(+) coinsertion during discharging,which can be confirmed by the lattice expansion,the formation of by-products including Zn_(x)(OTf)_(y)(OH)_(2x−y)·nH_(2)O,and the reduction of V^(4+)to V^(3+).Furthermore,the assembled Zn//pp-fibers@VO_(2)(B) pouch cells have excellent flexibility and stable electrochemical performance under various bending states,showing application possibilities for portable and wearable power sources.
基金financial support by the National Key R&D Program of China(No.2022YFB2502000)National Natural Science Foundation of China(Nos.52225208,52002352,U21A20174 and 52071295)Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang(No.2020R01002)。
文摘In order to solve the problem of poor conductivity of traditional LiFePO_(4)cathode binders,we developed sodium alginate-Congo red copolymers(SA-CR)as water-soluble electrically conductive and mechanically robust composite binder.Unlike most other electrically conductive polymer binders,the procedure is straightforward and low-cost to prepare SA-CR binder.Various SA-CR copolymers were prepared with different degree of compounding of CR to investigate the effect of CR on the electrochemical and physical properties of the prepared electrodes.The copolymer whose composition was filled with a mixture of SA and CR at a 3:1 mass ratio showed the best cell performance,due to the well-balanced electrical conductivity and mechanical properties.It exhibited a specific capacity of 118.8 m Ah/g at the 100th cycle with 92.1%capacity retention,significantly better than the 108.5 m Ah/g of conventional acetylene black electrodes.CR as a conduction-promoting agent in water-soluble composite binder favors the formation of continuous and homogenous conducting bridges throughout the electrode and increases the compaction density of electrode by reducing the conducting agent content of acetylene black and thus the improvement of electrode performance is realized.
基金supported by Hunan Provincial Science and Technology Department(No.2021JJ10058).
文摘Sulfide-based all-solid-state batteries(ASSBs)exhibit unparalleled application value due to the high ionic conductivity and good processability of sulfide solid electrolytes(SSEs).Carbon-based conductive agents(CAs)are often used in the construction of electronic conductive networks to achieve rapid electron transfer.However,CAs accelerate the formation of decomposition products of SSEs,and their effects on sulfide-based ASSBs are not fully understood.Herein,the effect of CAs(super P,vaper-grown carbonfibers,and carbon nanotubes)on the performance of sulfide-based ASSBs is investigated under different cathode active materials mass loading(8 and 25 mg⋅cm^(-2)).The results show that under low mass loading,the side reaction between the CAs and the SSEs deteriorates the performance of the cell,while the charge transfer promotion caused by the addition of CAs is only manifested under high mass loading.Furthermore,the gradient design strategy(enrichment of CAs near the current collector side and depletion of CAs near the electrolyte side)is applied to maximize the benefits of CAs in electron transport and reduce the adverse effects of CAs.The charge carrier transport barrier inside the high mass loading electrode is significantly reduced through the regulation of electronic conductivity.Consequently,the optimized electrode achieves a high areal capacity of 5.6 mAh⋅cm^(-2)at high current density(1.25 mA⋅cm2,0.2℃)at 25℃with a capacity retention of 87.85%after 100 cycles.This work provides a promising way for the design of high-mass loading electrodes with practical application value.