Li-rich layered oxide(LRLO)cathodes have been regarded as promising candidates for next-generation Li-ion batteries due to their exceptionally high energy density,which combines cationic and anionic redox activities.H...Li-rich layered oxide(LRLO)cathodes have been regarded as promising candidates for next-generation Li-ion batteries due to their exceptionally high energy density,which combines cationic and anionic redox activities.However,continuous voltage decay during cycling remains the primary obstacle for practical applications,which has yet to be fundamentally addressed.It is widely acknowledged that voltage decay originates from the irreversible migration of transition metal ions,which usually further exacerbates structural evolution and aggravates the irreversible oxygen redox reactions.Recently,constructing O2-type structure has been considered one of the most promising approaches for inhibiting voltage decay.In this review,the relationship between voltage decay and structural evolution is systematically elucidated.Strategies to suppress voltage decay are systematically summarized.Additionally,the design of O2-type structure and the corresponding mechanism of suppressing voltage decay are comprehensively discussed.Unfortunately,the reported O2-type LRLO cathodes still exhibit partially disordered structure with extended cycles.Herein,the factors that may cause the irreversible transition metal migrations in O2-type LRLO materials are also explored,while the perspectives and challenges for designing high-performance O2-type LRLO cathodes without voltage decay are proposed.展开更多
Li-S batteries are regarded as one of the most promising candidates for next-generation battery systems with high energy density and low cost.However,the dissolution-precipitation reaction mechanism of the sulfur(S)ca...Li-S batteries are regarded as one of the most promising candidates for next-generation battery systems with high energy density and low cost.However,the dissolution-precipitation reaction mechanism of the sulfur(S)cathode enhances the kinetics of the redox processes of the insulating sulfu r,which also arouses the notorious shuttle effect,leading to serious loss of S species and corrosion of Li anode.To get a balance between the shuttle restraining and the kinetic property,a combined strategy of electrolyte regulation and cathode modification is proposed via introducing 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoroprpyl ether(HFE)instead of 1,2-dimethoxyethane(DME),and SeS_(7)instead of S_8.The introduction of HFE tunes the solvation structure of the LiTFSI and the dissolution of intermediate polysulfides with Se doping(LiPSSes),and optimize the interface stability of the Li anode simultaneously.The minor Se substitution compensates the decrease in kinetic due to the decreased solubility of LiPSs.In this way,the Li-SeS_(7)batteries deliver a reversible capacity of 1062 and 1037 mAh g^(-1)with 2.0 and 5.5 mg SeS_(7)cm^(-2)loading condition,respectively.Besides,an electrolyte-electrode loading model is established to explain the relationship between the optimal electrolyte and cathode loading.It makes more sense to guide the electrolyte design for practical Li-S batteries.展开更多
Iron hexacyanoferrate(FeHCF)is a promising cathode material for sodium-ion batteries.However,FeHCF always suffers from a poor cycling stability,which is closely related to the abundant vacancy defects in its framework...Iron hexacyanoferrate(FeHCF)is a promising cathode material for sodium-ion batteries.However,FeHCF always suffers from a poor cycling stability,which is closely related to the abundant vacancy defects in its framework.Herein,post-synthetic and in-situ vacancy repairing strategies are proposed for the synthesis of highquality FeHCF in a highly concentrated Na_(4)Fe(CN)_(6) solution.Both the post-synthetic and in-situ vacancy repaired FeHCF products(FeHCF-P and FeHCF-I)show the significant decrease in the number of vacancy defects and the reinforced structure,which can suppress the side reactions and activate the capacity from low-spin Fe in FeHCF.In particular,FeHCF-P delivers a reversible discharge capacity of 131 mAh g^(−1) at 1 C and remains 109 mAh g^(−1) after 500 cycles,with a capacity retention of 83%.FeHCF-I can deliver a high discharge capacity of 158.5 mAh g^(−1) at 1 C.Even at 10 C,the FeHCF-I electrode still maintains a discharge specific capacity of 103 mAh g^(−1) and retains 75% after 800 cycles.This work provides a new vacancy repairing strategy for the solution synthesis of high-quality FeHCF.展开更多
The development of polymer-based solid-state batteries is severely limited by the low ionic conductivity of solid polymer electrolyte and the instable interface between polymer electrolyte and Li-metal anode.In this w...The development of polymer-based solid-state batteries is severely limited by the low ionic conductivity of solid polymer electrolyte and the instable interface between polymer electrolyte and Li-metal anode.In this work,lithium iodide(LiI)as a bifunctional additive was introduced into the poly(ethylene oxide)(PEO)-based electrolyte to improve the ionic conductivity and to construct a stable interphase at the Li/PEO interface.I-anions offer a strong electrostatic interaction with hydrogen atoms on PEO chains(HPEO)and forming massive I–H bonds that cross-link PEO chains,decrease crystallinity of PEO,and thus improve Li~+interchain transport.In addition,LiI participates in the formation of an inorganic-rich interphase layer,which decreases the energy barrier of Li+transport across the interface and thus inhibits the growth of lithium dendrites.As a result,the composite PEO electrolyte with 2 wt%LiI(PEO-2 LiI)presents a very high ionic conductivity of 2.1×10^(-4) S cm-1 and a critical current density of 2.0 m A cm^(-2) at 45°C.Li symmetric cell with this PEO-2 LiI electrolyte exhibits a long-term cyclability over 600 h at 0.2 m A cm^(-2).Furthermore,solid-state LiFePO_(4) and LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2) batteries with the PEO-2 LiI electrolyte show an impressive electrochemical performance with outstanding cycling stability and rate capability at 45°C.展开更多
The sulfur cathodes operating via solid phase conversion of sulfur have natural advantages in suppressing polysulfide dissolution and lowering the electrolyte dosage,and thus realizing significant improvements in both...The sulfur cathodes operating via solid phase conversion of sulfur have natural advantages in suppressing polysulfide dissolution and lowering the electrolyte dosage,and thus realizing significant improvements in both cycle life and energy density.To realize an ideal solid-phase conversion of sulfur,a deep understanding of the regulation path of reaction mechanism and a corresponding intentional material and/or cathode design are highly essential.Herein,via covalently fixing of sulfur onto the triallyl isocyanurate,a series of S-triallyl isocyanurate organosulfur polymer composites(STIs) are developed.Relationship between the structure and the electrochemical conversion behavior of STIs is systematically investigated.It is found that the structure of STIs varies with the synthetic temperature,and correspondingly the electrochemical redox of sulfur can be controlled from conventional "solid-liquid-solid" conversion to the "solid-solid" one.Among the STI series,the STI-5 composite realizes an ideal solid-phase conversion and demonstrates great potential for building a Li-S battery with high-energy density and long-cyclelife:it realizes stable cycling over 1000 cycles in carbonate electrolyte,with a degradation rate of0.053% per cycle;the corresponding pouch cell shows almost no capacity decay for 125 cycles under the conditions of high sulfur loading(4.5 mg cm^(-2)) and lean electrolyte(8 μL mg_s^(-1)).In addition,the tailoring strategy of STI can also apply to other precursors with allyl functional groups to develop new organosulfur polymers for "solid-solid" sulfur cathodes.The vulcanized triallyl phosphate(STP) and triallylamine(STA) both show great lithium storage potential.This strategy successfully develops a new family of organosulfur polymers as cathodes for Li-S batteries via solid-phase conversion of sulfur,and brings insights to the mechanism study in Li-S batteries.展开更多
Sulfurized polyacrylonitrile(SPAN)as a promising cathode material for lithium sulfur(Li-S)batteries has drawn increasing attention for its improved electrochemical performance in carbonate-based electrolyte.However,th...Sulfurized polyacrylonitrile(SPAN)as a promising cathode material for lithium sulfur(Li-S)batteries has drawn increasing attention for its improved electrochemical performance in carbonate-based electrolyte.However,the relatively poor electronic and ionic conductivities of SPAN limit its high-rate and lowtemperature performances.In this work,a novel one-dimensional nanofiber SPAN(SFPAN)composite is developed as the cathode material for Li-S batteries.Benefitting from its one-dimensional nanostructure,the SFPAN composite cathode provides fast channels for the migration of ions and electronics,thus effectively improving its electrochemical performance at high rates and low temperature.As a result,the SFPAN maintains a high reversible specific capacity^1200 mAh g−1 after 400 cycles at 0.3 A g−1 and can deliver a high capacity of^850 mAh g−1 even at a high current density of 12.5 A g−1.What is more,the SFPAN can achieve a capacity of^800 mAh g−1 at 0℃and^1550 mAh g−1 at 60℃,thus providing a wider temperature range of applications.This work provides new perspectives on the cathode design for high-rate lithium-sulfur batteries.展开更多
Lithium sulfide (Li2S) provides a promising route for lithium storage due to high theoretical specific capacity (1166 mAh g-1). The electrochemical performance of Li2S can be significantly enhanced by forming Li2S-car...Lithium sulfide (Li2S) provides a promising route for lithium storage due to high theoretical specific capacity (1166 mAh g-1). The electrochemical performance of Li2S can be significantly enhanced by forming Li2S-carbon composites with the introduction of carbon. However, the complex synthesis method of Li2S-carbon composites restrains the large-scale productivity. Herein, we propose a facile route to prepare carbon coated Li2S-carbon nanotube composites (Li2S@C-CNT) via spray drying and heat treatment, which is a low-cost and large-scale method for facile synthesis of Li2S-carbon composites. For the Li2S@C-CNT composites, Li2S nanoparticles are contacted with surrounding particles due to the 3D CNTs framework. The novel construction not only suppresses the diffusion of polysulfides during cycling, but also remarkably accelerates the transport of electron and ion, resulting in a high specific capacity (1100 mAh g^-1) and good cycling performance. The rational designed architecture and good electrochemical performance of Li2S@C-CNT will pave the avenue for realizing high energy density of Li2S-based batteries.展开更多
LiCoO_(2) is the preferred cathode material for consumer electronic products due to its high volumetric energy density. However, the unfavorable phase transition and surface oxygen release limits the practical applica...LiCoO_(2) is the preferred cathode material for consumer electronic products due to its high volumetric energy density. However, the unfavorable phase transition and surface oxygen release limits the practical application of LiCoO_(2)at a high-voltage of 4.6 V to achieve a higher energy density demanded by the market. Herein, both bulk and surface structures of LiCoO_(2)are stabilized at 4.6 V through oxygen charge regulation by Gd-gradient doping. The enrichment of highly electropositive Gd on LiCoO_(2) surface will increase the effective charge on oxygen and improve the oxygen framework stability against oxygen loss.On the other hand, Gd ions occupy the Co-sites and suppress the unfavorable phase transition and microcrack. The modified LiCoO_(2) exhibits superior cycling stability with capacity retention of 90.1% over 200 cycles at 4.6 V, and also obtains a high capacity of 145.7 m Ah/g at 5 C. This work shows great promise for developing high-voltage LiCoO_(2) at 4.6 V and the strategy could also contribute to optimizing other cathode materials with high voltage and large capacity, such as cobalt-free high-nickel and lithiumrich manganese-based cathode materials.展开更多
Lithium-selenium(Li-Se) battery is a promising system with high theoretical gravimetric and volumetric energy densities, while its long-term cyclability is hard to realize, especially when a practical Se cathode with ...Lithium-selenium(Li-Se) battery is a promising system with high theoretical gravimetric and volumetric energy densities, while its long-term cyclability is hard to realize, especially when a practical Se cathode with high Se content, high Se loading, and high density is employed. The main obstacles are the sluggish conversion kinetics of the dense Se cathodes and the continuous deterioration of the Li-metal anodes.Here, by introducing an acetonitrile(AN)-based electrolyte and replacing the Li electrode with a lithiated graphite, we successfully build a hybrid conversion-intercalation system using a high-content(80 wt%),decent-loading(3.0 mg cm^(-2)), and low-porosity(44%) Se cathode. The as-designed lithiated graphite||Se(LG||Se) cell demonstrated a high Se utilization(97.4%), a long cycle life(3000 cycles), and an ultrahigh average Coulombic efficiency(99.98%). The cell also works well under lean-electrolyte(2 l L mg^(-1)) condition and shows outstanding safety performance in the nail-penetrating test. The combination affords the competitive comprehensive performances, including high volumetric and gravimetric energy densities, long cycling life, and superb safety of the LG||Se cell. In addition, with a newly-designed threeelectrode pouch cell, the lithiation of the graphite anodes could be done with an in-situ lithiation process,indicating the high potential of the as-proposed LG||Se cell for the practical applications.展开更多
Lithium(Li)metal electrodes show significantly different reversibility in the electrolytes with different salts.However,the understanding on how the salts impact on the Li loss remains unclear.Herein,using the electro...Lithium(Li)metal electrodes show significantly different reversibility in the electrolytes with different salts.However,the understanding on how the salts impact on the Li loss remains unclear.Herein,using the electrolytes with different salts(e.g.,lithium hexafluorophosphate(LiPF_(6)),lithium difluoro(oxalato)borate(LiDFOB),and lithium bis(fluorosulfonyl)amide(LiFSI))as examples,we decouple the irreversible Li loss(SEI Li^(+)and“dead”Li)during cycling.It is found that the accumulation of both SEI Li^(+)and“dead”Li may be responsible to the irreversible Li loss for the Li metal in the electrolyte with LiPF_(6)salt.While for the electrolytes with LiDFOB and LiFSI salts,the accumulation of“dead”Li predominates the Li loss.We also demonstrate that lithium nitrate and fluoroethylene carbonate additives could,respectively,function as the“dead”Li and SEI Li^(+)inhibitors.Inspired by the above understandings,we propose a universal procedure for the electrolyte design of Li metal batteries(LMBs):(i)decouple and find the main reason for the irreversible Li loss;(ii)add the corresponding electrolyte additive.With such a Li-loss-targeted strategy,the Li reversibility was significantly enhanced in the electrolytes with 1,2-dimethoxyethane,triethyl phosphate,and tetrahydrofuran solvents.Our strategy may broaden the scope of electrolyte design toward practical LMBs.展开更多
Polymer materials offer controllable structure-dependent performances in separation,catalysis and drug release.Their molecular structures can be precisely tailored to accept Li^(+)for energy storage applications.Here ...Polymer materials offer controllable structure-dependent performances in separation,catalysis and drug release.Their molecular structures can be precisely tailored to accept Li^(+)for energy storage applications.Here the design of sp^(2)carbon-based polyphenylene(PPH)with high lithium-ion uptakes and long-term stability is reported.Linear-PPH(L-PPH)exceeds the performance of crosslink-PPH(C-PPH),due to the fact that it has an ordered lamellar structure,promoting the Li^(+)intercalation/deintercalation channel.The L-PPH cell shows a clear charge and discharge plateau at 0.35 and 0.15 V vs.Li^(+)/Li,respectively,which is absent in the C-PPH cell.The Li^(+)storage capacity of L-PPH is five times that of the C-PPH.The reversible storage capacity is further improved to 261 m Ah g;by functionalizing the L-PPH with the–SO_(3)H groups.In addition,the Li-intercalated structures of C-PPH and L-PPH are investigated via near-edge X-ray absorption fine structure(NEXAFS),suggesting the high reversible Li^(+)–C=C bond interaction at L-PPH.This strategy,based on new insight into sp^(2)functional groups,is the first step toward a molecular understanding of the structure storage-capacity relationship in sp^(2)carbon-based polymer.展开更多
Micron-sized silicon(μSi)is a promising anode material for next-generation lithium-ion batteries due to its high specific capacity,low cost,and abundant reserves.However,the volume expansion that occurs during cyclin...Micron-sized silicon(μSi)is a promising anode material for next-generation lithium-ion batteries due to its high specific capacity,low cost,and abundant reserves.However,the volume expansion that occurs during cycling leads to the accumulation of undesirable stresses,resulting in pulverization of silicon microparticles and shortened lifespan of the batteries.Herein,a composite film of Cu-PET-Cu is proposed as the current collector(CC)forμSi anodes to replace the conventional Cu CC.Cu-PET-Cu CC is prepared by depositing Cu on both sides of a polyethylene terephthalate(PET)film.The PET layer promises good ductility of the film,permitting the Cu-PET-Cu CC to accommodate the volumetric changes of silicon microparticles and facilitates the stress release through ductile deformation.As a result,theμSi electrode with Cu-PET-Cu CC retains a high specific capacity of 2181 mA h g^(-1),whereas theμSi electrode with Cu CC(μSi/Cu)exhibits a specific capacity of 1285 mA h g^(-1)after 80 cycles.The stress relieving effect of CuPET-Cu was demonstrated by in-situ fiber optic stress monitoring and multi-physics simulations.This work proposes an effective stress relief strategy at the electrode level for the practical implementation ofμSi anodes.展开更多
基金funded by the National Natural Science Foundation of China(Grant Nos.22279092 and 5202780089).
文摘Li-rich layered oxide(LRLO)cathodes have been regarded as promising candidates for next-generation Li-ion batteries due to their exceptionally high energy density,which combines cationic and anionic redox activities.However,continuous voltage decay during cycling remains the primary obstacle for practical applications,which has yet to be fundamentally addressed.It is widely acknowledged that voltage decay originates from the irreversible migration of transition metal ions,which usually further exacerbates structural evolution and aggravates the irreversible oxygen redox reactions.Recently,constructing O2-type structure has been considered one of the most promising approaches for inhibiting voltage decay.In this review,the relationship between voltage decay and structural evolution is systematically elucidated.Strategies to suppress voltage decay are systematically summarized.Additionally,the design of O2-type structure and the corresponding mechanism of suppressing voltage decay are comprehensively discussed.Unfortunately,the reported O2-type LRLO cathodes still exhibit partially disordered structure with extended cycles.Herein,the factors that may cause the irreversible transition metal migrations in O2-type LRLO materials are also explored,while the perspectives and challenges for designing high-performance O2-type LRLO cathodes without voltage decay are proposed.
基金supported by the National Natural Science Foundation of China(22075091)the Natural Science Foundation of Hubei Province(Grant No.2021CFA066)。
文摘Li-S batteries are regarded as one of the most promising candidates for next-generation battery systems with high energy density and low cost.However,the dissolution-precipitation reaction mechanism of the sulfur(S)cathode enhances the kinetics of the redox processes of the insulating sulfu r,which also arouses the notorious shuttle effect,leading to serious loss of S species and corrosion of Li anode.To get a balance between the shuttle restraining and the kinetic property,a combined strategy of electrolyte regulation and cathode modification is proposed via introducing 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoroprpyl ether(HFE)instead of 1,2-dimethoxyethane(DME),and SeS_(7)instead of S_8.The introduction of HFE tunes the solvation structure of the LiTFSI and the dissolution of intermediate polysulfides with Se doping(LiPSSes),and optimize the interface stability of the Li anode simultaneously.The minor Se substitution compensates the decrease in kinetic due to the decreased solubility of LiPSs.In this way,the Li-SeS_(7)batteries deliver a reversible capacity of 1062 and 1037 mAh g^(-1)with 2.0 and 5.5 mg SeS_(7)cm^(-2)loading condition,respectively.Besides,an electrolyte-electrode loading model is established to explain the relationship between the optimal electrolyte and cathode loading.It makes more sense to guide the electrolyte design for practical Li-S batteries.
基金supported by the projects of the National Key R&D Program of China(2016YFB0100302)the National Natural Science Foundation of China(Grant No.60306011).
文摘Iron hexacyanoferrate(FeHCF)is a promising cathode material for sodium-ion batteries.However,FeHCF always suffers from a poor cycling stability,which is closely related to the abundant vacancy defects in its framework.Herein,post-synthetic and in-situ vacancy repairing strategies are proposed for the synthesis of highquality FeHCF in a highly concentrated Na_(4)Fe(CN)_(6) solution.Both the post-synthetic and in-situ vacancy repaired FeHCF products(FeHCF-P and FeHCF-I)show the significant decrease in the number of vacancy defects and the reinforced structure,which can suppress the side reactions and activate the capacity from low-spin Fe in FeHCF.In particular,FeHCF-P delivers a reversible discharge capacity of 131 mAh g^(−1) at 1 C and remains 109 mAh g^(−1) after 500 cycles,with a capacity retention of 83%.FeHCF-I can deliver a high discharge capacity of 158.5 mAh g^(−1) at 1 C.Even at 10 C,the FeHCF-I electrode still maintains a discharge specific capacity of 103 mAh g^(−1) and retains 75% after 800 cycles.This work provides a new vacancy repairing strategy for the solution synthesis of high-quality FeHCF.
基金supported by the National Science Foundation of China(Grant No.5202780089)the Fundamental Research Funds for the Central Universities(HUST:2172020kfy XJJS089)。
文摘The development of polymer-based solid-state batteries is severely limited by the low ionic conductivity of solid polymer electrolyte and the instable interface between polymer electrolyte and Li-metal anode.In this work,lithium iodide(LiI)as a bifunctional additive was introduced into the poly(ethylene oxide)(PEO)-based electrolyte to improve the ionic conductivity and to construct a stable interphase at the Li/PEO interface.I-anions offer a strong electrostatic interaction with hydrogen atoms on PEO chains(HPEO)and forming massive I–H bonds that cross-link PEO chains,decrease crystallinity of PEO,and thus improve Li~+interchain transport.In addition,LiI participates in the formation of an inorganic-rich interphase layer,which decreases the energy barrier of Li+transport across the interface and thus inhibits the growth of lithium dendrites.As a result,the composite PEO electrolyte with 2 wt%LiI(PEO-2 LiI)presents a very high ionic conductivity of 2.1×10^(-4) S cm-1 and a critical current density of 2.0 m A cm^(-2) at 45°C.Li symmetric cell with this PEO-2 LiI electrolyte exhibits a long-term cyclability over 600 h at 0.2 m A cm^(-2).Furthermore,solid-state LiFePO_(4) and LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2) batteries with the PEO-2 LiI electrolyte show an impressive electrochemical performance with outstanding cycling stability and rate capability at 45°C.
基金supported by the National Science Foundation of China (22075091)the National Science Foundation of Hubei Province (2021CFA066)。
文摘The sulfur cathodes operating via solid phase conversion of sulfur have natural advantages in suppressing polysulfide dissolution and lowering the electrolyte dosage,and thus realizing significant improvements in both cycle life and energy density.To realize an ideal solid-phase conversion of sulfur,a deep understanding of the regulation path of reaction mechanism and a corresponding intentional material and/or cathode design are highly essential.Herein,via covalently fixing of sulfur onto the triallyl isocyanurate,a series of S-triallyl isocyanurate organosulfur polymer composites(STIs) are developed.Relationship between the structure and the electrochemical conversion behavior of STIs is systematically investigated.It is found that the structure of STIs varies with the synthetic temperature,and correspondingly the electrochemical redox of sulfur can be controlled from conventional "solid-liquid-solid" conversion to the "solid-solid" one.Among the STI series,the STI-5 composite realizes an ideal solid-phase conversion and demonstrates great potential for building a Li-S battery with high-energy density and long-cyclelife:it realizes stable cycling over 1000 cycles in carbonate electrolyte,with a degradation rate of0.053% per cycle;the corresponding pouch cell shows almost no capacity decay for 125 cycles under the conditions of high sulfur loading(4.5 mg cm^(-2)) and lean electrolyte(8 μL mg_s^(-1)).In addition,the tailoring strategy of STI can also apply to other precursors with allyl functional groups to develop new organosulfur polymers for "solid-solid" sulfur cathodes.The vulcanized triallyl phosphate(STP) and triallylamine(STA) both show great lithium storage potential.This strategy successfully develops a new family of organosulfur polymers as cathodes for Li-S batteries via solid-phase conversion of sulfur,and brings insights to the mechanism study in Li-S batteries.
基金supported by the National Natural Science Foundation of China(Grant nos.21773077,51632001,and 51532005)the Ministry of Science and Technology“973”program(Grant No.2015CB258400)the National Key R&D Program of China(2018YFB0905400)。
文摘Sulfurized polyacrylonitrile(SPAN)as a promising cathode material for lithium sulfur(Li-S)batteries has drawn increasing attention for its improved electrochemical performance in carbonate-based electrolyte.However,the relatively poor electronic and ionic conductivities of SPAN limit its high-rate and lowtemperature performances.In this work,a novel one-dimensional nanofiber SPAN(SFPAN)composite is developed as the cathode material for Li-S batteries.Benefitting from its one-dimensional nanostructure,the SFPAN composite cathode provides fast channels for the migration of ions and electronics,thus effectively improving its electrochemical performance at high rates and low temperature.As a result,the SFPAN maintains a high reversible specific capacity^1200 mAh g−1 after 400 cycles at 0.3 A g−1 and can deliver a high capacity of^850 mAh g−1 even at a high current density of 12.5 A g−1.What is more,the SFPAN can achieve a capacity of^800 mAh g−1 at 0℃and^1550 mAh g−1 at 60℃,thus providing a wider temperature range of applications.This work provides new perspectives on the cathode design for high-rate lithium-sulfur batteries.
基金supported by the National Basic Research Program of China (973 Program, 2015CB258400)the National Science Foundation of China (Grant Nos. 21773077 and 51532005)the Program for HUST Interdisciplinary Innovation Team (2015ZDTD021)
文摘Lithium sulfide (Li2S) provides a promising route for lithium storage due to high theoretical specific capacity (1166 mAh g-1). The electrochemical performance of Li2S can be significantly enhanced by forming Li2S-carbon composites with the introduction of carbon. However, the complex synthesis method of Li2S-carbon composites restrains the large-scale productivity. Herein, we propose a facile route to prepare carbon coated Li2S-carbon nanotube composites (Li2S@C-CNT) via spray drying and heat treatment, which is a low-cost and large-scale method for facile synthesis of Li2S-carbon composites. For the Li2S@C-CNT composites, Li2S nanoparticles are contacted with surrounding particles due to the 3D CNTs framework. The novel construction not only suppresses the diffusion of polysulfides during cycling, but also remarkably accelerates the transport of electron and ion, resulting in a high specific capacity (1100 mAh g^-1) and good cycling performance. The rational designed architecture and good electrochemical performance of Li2S@C-CNT will pave the avenue for realizing high energy density of Li2S-based batteries.
基金supported by the National Natural Science Foundation of China (52102249, 52172201, 51732005, 51902118)the China Postdoctoral Science Foundation (2019M662609 and 2020T130217)+1 种基金the international postdoctoral exchange fellowship program (PC2021026)the Major Technological Innovation Project of Hubei Province (2019AAA019) for financial support。
文摘LiCoO_(2) is the preferred cathode material for consumer electronic products due to its high volumetric energy density. However, the unfavorable phase transition and surface oxygen release limits the practical application of LiCoO_(2)at a high-voltage of 4.6 V to achieve a higher energy density demanded by the market. Herein, both bulk and surface structures of LiCoO_(2)are stabilized at 4.6 V through oxygen charge regulation by Gd-gradient doping. The enrichment of highly electropositive Gd on LiCoO_(2) surface will increase the effective charge on oxygen and improve the oxygen framework stability against oxygen loss.On the other hand, Gd ions occupy the Co-sites and suppress the unfavorable phase transition and microcrack. The modified LiCoO_(2) exhibits superior cycling stability with capacity retention of 90.1% over 200 cycles at 4.6 V, and also obtains a high capacity of 145.7 m Ah/g at 5 C. This work shows great promise for developing high-voltage LiCoO_(2) at 4.6 V and the strategy could also contribute to optimizing other cathode materials with high voltage and large capacity, such as cobalt-free high-nickel and lithiumrich manganese-based cathode materials.
基金supported by the National Natural Science Foundation of China under Grant No. 51802225the funding from the State Key Laboratory of Materials Processing and Die & Mould Technology, Huazhong University of Science and Technology (P2020-001)。
文摘Lithium-selenium(Li-Se) battery is a promising system with high theoretical gravimetric and volumetric energy densities, while its long-term cyclability is hard to realize, especially when a practical Se cathode with high Se content, high Se loading, and high density is employed. The main obstacles are the sluggish conversion kinetics of the dense Se cathodes and the continuous deterioration of the Li-metal anodes.Here, by introducing an acetonitrile(AN)-based electrolyte and replacing the Li electrode with a lithiated graphite, we successfully build a hybrid conversion-intercalation system using a high-content(80 wt%),decent-loading(3.0 mg cm^(-2)), and low-porosity(44%) Se cathode. The as-designed lithiated graphite||Se(LG||Se) cell demonstrated a high Se utilization(97.4%), a long cycle life(3000 cycles), and an ultrahigh average Coulombic efficiency(99.98%). The cell also works well under lean-electrolyte(2 l L mg^(-1)) condition and shows outstanding safety performance in the nail-penetrating test. The combination affords the competitive comprehensive performances, including high volumetric and gravimetric energy densities, long cycling life, and superb safety of the LG||Se cell. In addition, with a newly-designed threeelectrode pouch cell, the lithiation of the graphite anodes could be done with an in-situ lithiation process,indicating the high potential of the as-proposed LG||Se cell for the practical applications.
基金This work was supported by the National Key Research and Development Program(2021YFB2400300)the National Natural Science Foundation of China(52272203)the Fundamental Research Funds for the Central Universities(2021GCRC001).
文摘Lithium(Li)metal electrodes show significantly different reversibility in the electrolytes with different salts.However,the understanding on how the salts impact on the Li loss remains unclear.Herein,using the electrolytes with different salts(e.g.,lithium hexafluorophosphate(LiPF_(6)),lithium difluoro(oxalato)borate(LiDFOB),and lithium bis(fluorosulfonyl)amide(LiFSI))as examples,we decouple the irreversible Li loss(SEI Li^(+)and“dead”Li)during cycling.It is found that the accumulation of both SEI Li^(+)and“dead”Li may be responsible to the irreversible Li loss for the Li metal in the electrolyte with LiPF_(6)salt.While for the electrolytes with LiDFOB and LiFSI salts,the accumulation of“dead”Li predominates the Li loss.We also demonstrate that lithium nitrate and fluoroethylene carbonate additives could,respectively,function as the“dead”Li and SEI Li^(+)inhibitors.Inspired by the above understandings,we propose a universal procedure for the electrolyte design of Li metal batteries(LMBs):(i)decouple and find the main reason for the irreversible Li loss;(ii)add the corresponding electrolyte additive.With such a Li-loss-targeted strategy,the Li reversibility was significantly enhanced in the electrolytes with 1,2-dimethoxyethane,triethyl phosphate,and tetrahydrofuran solvents.Our strategy may broaden the scope of electrolyte design toward practical LMBs.
基金funded by the Engineering and Physical Sciences Research Council(EPSRC)(EP/P02467X/1 and EP/S018204/1)the Centre for Nature Inspired Chemical Engineering(EP K038656/1)。
文摘Polymer materials offer controllable structure-dependent performances in separation,catalysis and drug release.Their molecular structures can be precisely tailored to accept Li^(+)for energy storage applications.Here the design of sp^(2)carbon-based polyphenylene(PPH)with high lithium-ion uptakes and long-term stability is reported.Linear-PPH(L-PPH)exceeds the performance of crosslink-PPH(C-PPH),due to the fact that it has an ordered lamellar structure,promoting the Li^(+)intercalation/deintercalation channel.The L-PPH cell shows a clear charge and discharge plateau at 0.35 and 0.15 V vs.Li^(+)/Li,respectively,which is absent in the C-PPH cell.The Li^(+)storage capacity of L-PPH is five times that of the C-PPH.The reversible storage capacity is further improved to 261 m Ah g;by functionalizing the L-PPH with the–SO_(3)H groups.In addition,the Li-intercalated structures of C-PPH and L-PPH are investigated via near-edge X-ray absorption fine structure(NEXAFS),suggesting the high reversible Li^(+)–C=C bond interaction at L-PPH.This strategy,based on new insight into sp^(2)functional groups,is the first step toward a molecular understanding of the structure storage-capacity relationship in sp^(2)carbon-based polymer.
基金supported by the the National Key R&D Program of China(2022YFB3803500)the Natural Science Foundation of Hubei Province(2021CFA066).
文摘Micron-sized silicon(μSi)is a promising anode material for next-generation lithium-ion batteries due to its high specific capacity,low cost,and abundant reserves.However,the volume expansion that occurs during cycling leads to the accumulation of undesirable stresses,resulting in pulverization of silicon microparticles and shortened lifespan of the batteries.Herein,a composite film of Cu-PET-Cu is proposed as the current collector(CC)forμSi anodes to replace the conventional Cu CC.Cu-PET-Cu CC is prepared by depositing Cu on both sides of a polyethylene terephthalate(PET)film.The PET layer promises good ductility of the film,permitting the Cu-PET-Cu CC to accommodate the volumetric changes of silicon microparticles and facilitates the stress release through ductile deformation.As a result,theμSi electrode with Cu-PET-Cu CC retains a high specific capacity of 2181 mA h g^(-1),whereas theμSi electrode with Cu CC(μSi/Cu)exhibits a specific capacity of 1285 mA h g^(-1)after 80 cycles.The stress relieving effect of CuPET-Cu was demonstrated by in-situ fiber optic stress monitoring and multi-physics simulations.This work proposes an effective stress relief strategy at the electrode level for the practical implementation ofμSi anodes.
