Magnesium hydride(MgH_(2)) is a candidate material for hydrogen storage.MgH_(2)-AlH_(3) composite shows superior hydrogen desorption properties than pure MgH_(2).However,this composite still suffers from poor cycling ...Magnesium hydride(MgH_(2)) is a candidate material for hydrogen storage.MgH_(2)-AlH_(3) composite shows superior hydrogen desorption properties than pure MgH_(2).However,this composite still suffers from poor cycling performance.In this work,NbF_(5) was utilized to improve the cycling properties of the MgH_(2)-AlH_(3) composite.Cycling hydrogen desorption studies show that NbF_(5) significantly improves the cycling stability of MgH_(2)-AlH_(3).The MgH_(2)-AlH_(3)-NbF_(5) composite can release about 2.7 wt% of hydrogen at 300℃ for 1 h and the hydrogen desorption capacity can maintain at 2.7 wt% for more than100 cycles.In comparison,the hydrogen desorption capacity of the MgH_(2)-AlH_(3) composite is decreasing with the cycle number increasing.The capacity is reduced from a maximum value of 3.3 wt% to about 1.0 wt% after 40 cycles.Brunauer-Emmett-Teller(BET) surface area measurements show that the particle size of MgH_(2)-AlH_(3) composite decreases after cycling,which means pulverization of the composite.NbF_(5) can to some extent suppress the pulverization of the composite during cycling,which partially contributes to the improvement of the cycling hydrogen desorption properties of the material.展开更多
Layered oxide is a promising cathode material for sodium-ion batteries because of its high-capacity,high operating voltage,and simple synthesis.Cycling performance is an important criterion for evaluating the applicat...Layered oxide is a promising cathode material for sodium-ion batteries because of its high-capacity,high operating voltage,and simple synthesis.Cycling performance is an important criterion for evaluating the application prospects of batteries.However,facing challenges,including phase transitions,ambient stability,side reactions,and irreversible anionic oxygen activity,the cycling performance of layered oxide cathode materials still cannot meet the application requirements.Therefore,this review proposes several strategies to address these challenges.First,bulk doping is introduced from three aspects:cationic single doping,anionic single doping,and multi-ion doping.Second,homogeneous surface coating and concentration gradient modification are reviewed.In addition,methods such as mixed structure design,particle engineering,high-entropy material construction,and integrated modification are proposed.Finally,a summary and outlook provide a new horizon for developing and modifying layered oxide cathode materials.展开更多
Rechargeable alkaline aqueous zinc batteries(RAZBs)have attracted increasing attention.However,most RAZBs are hindered by the limited availability of cathode materials.The practical electrochemical performance of most...Rechargeable alkaline aqueous zinc batteries(RAZBs)have attracted increasing attention.However,most RAZBs are hindered by the limited availability of cathode materials.The practical electrochemical performance of most cathode materials is lower than the theoretical value due to their poor electrical conductivity and low utilization capacity.In this work,we develop a facile hydrothermal procedure to prepare highly uniform bimetallic sulfides as novel cathode materials for RAZBs.Copper-cobalt binary metallic oxides materials possess higher conductivity and larger capacity compared with their mono-metal oxides compounds due to bimetallic synergistic effects and multiple oxidation states.Furthermore,bimetallic sulfide compounds have smaller bond energy and longer bond length than their oxides,leading to less structural damage,faster kinetics of electrochemical reactions,and better stability.The as-prepared Co-Cu bimetallic sulfides show enhanced electrochemical performance due to various valences of Co and Cu as well as the existence of S.As a result,aqueous Zn/CuCo_(2)S_(4) battery shows a high specific capacity of 117.4 mAh/g at 4 A/g and a good cycle life of over 8000 cycles.Based on PANa hydrogel electrolytes,a flexible Zn/CuCo_(2)S_(4) battery demonstrates excellent cycling stability.This battery can also meet the requirements of electronic devices with different shapes and performs well in extreme environments,such as freezing,drilling,and hammering.This work opens new avenues to obtain high-rate and long-life cathode materials for RAZBs by utilizing the synergistic effects of bimetallic sulfides and provides a new platform for flexible energy storage devices.展开更多
Al_2O_3-coated spinel LiMn_2O_4 cathode materials, presintered LiMn_2O_4(P-LMO), and calcined LiMn_2O_4(C-LMO) were synthesized by chemical deposition and thermal treating method using presintered and calcined LiMn_2O...Al_2O_3-coated spinel LiMn_2O_4 cathode materials, presintered LiMn_2O_4(P-LMO), and calcined LiMn_2O_4(C-LMO) were synthesized by chemical deposition and thermal treating method using presintered and calcined LiMn_2O_4 as precursors. The crystal structure, morphology,the thickness of the coating layer, and particle size of prepared samples were investigated by X-ray diffraction(XRD), scanning electron microscopy(SEM), high-resolution transmission electron microscopy(HRTEM), and Malvern instruments. The average particle size of P-LMO with like-spheres(0.3 μm) is much smaller than that of C-LMO(0.5 μm). The Al_2O_3 layer of P-LMO can effectively reduce the charge transfer resistance and inhibit the Mn dissolution. The electrochemical performance of P-LMO is better than that of C-LMO. It is found that the LiMn_2O_4 cathode materials have excellent electrochemical cyclability by coated 2 mol% Al_2O_3 at the surface of presintered material. The initial discharge capacity of the material with 2 mol% Al_2O_3-coated is 114.0 m Ah·g^(-1) at 0.1 C rate and 55 ℃, and the capacity retention is 87.3 % at 0.5 C rate.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.51771171 and 51971199)the Natural Science Foundation of Guangxi Province(Nos.2019GXNSFBA185004 and 2018GXNSFAA281308)the Basic Ability Improvement Project for Young and Middle-Aged Teachers in Colleges and Universities in Guangxi(No.2019KY0021)。
文摘Magnesium hydride(MgH_(2)) is a candidate material for hydrogen storage.MgH_(2)-AlH_(3) composite shows superior hydrogen desorption properties than pure MgH_(2).However,this composite still suffers from poor cycling performance.In this work,NbF_(5) was utilized to improve the cycling properties of the MgH_(2)-AlH_(3) composite.Cycling hydrogen desorption studies show that NbF_(5) significantly improves the cycling stability of MgH_(2)-AlH_(3).The MgH_(2)-AlH_(3)-NbF_(5) composite can release about 2.7 wt% of hydrogen at 300℃ for 1 h and the hydrogen desorption capacity can maintain at 2.7 wt% for more than100 cycles.In comparison,the hydrogen desorption capacity of the MgH_(2)-AlH_(3) composite is decreasing with the cycle number increasing.The capacity is reduced from a maximum value of 3.3 wt% to about 1.0 wt% after 40 cycles.Brunauer-Emmett-Teller(BET) surface area measurements show that the particle size of MgH_(2)-AlH_(3) composite decreases after cycling,which means pulverization of the composite.NbF_(5) can to some extent suppress the pulverization of the composite during cycling,which partially contributes to the improvement of the cycling hydrogen desorption properties of the material.
基金the Fundamental Research Funds for the Central Universities,China(No.06500177)the National Natural Science Foundation of China Joint Fund Project(No.U1764255)。
文摘Layered oxide is a promising cathode material for sodium-ion batteries because of its high-capacity,high operating voltage,and simple synthesis.Cycling performance is an important criterion for evaluating the application prospects of batteries.However,facing challenges,including phase transitions,ambient stability,side reactions,and irreversible anionic oxygen activity,the cycling performance of layered oxide cathode materials still cannot meet the application requirements.Therefore,this review proposes several strategies to address these challenges.First,bulk doping is introduced from three aspects:cationic single doping,anionic single doping,and multi-ion doping.Second,homogeneous surface coating and concentration gradient modification are reviewed.In addition,methods such as mixed structure design,particle engineering,high-entropy material construction,and integrated modification are proposed.Finally,a summary and outlook provide a new horizon for developing and modifying layered oxide cathode materials.
基金supported by National Natural Science Foundation of China(No.22005207)Guangdong Basic and Applied Basic Research Foundation(Nos.2019A1515011819,2020A1515110442)。
文摘Rechargeable alkaline aqueous zinc batteries(RAZBs)have attracted increasing attention.However,most RAZBs are hindered by the limited availability of cathode materials.The practical electrochemical performance of most cathode materials is lower than the theoretical value due to their poor electrical conductivity and low utilization capacity.In this work,we develop a facile hydrothermal procedure to prepare highly uniform bimetallic sulfides as novel cathode materials for RAZBs.Copper-cobalt binary metallic oxides materials possess higher conductivity and larger capacity compared with their mono-metal oxides compounds due to bimetallic synergistic effects and multiple oxidation states.Furthermore,bimetallic sulfide compounds have smaller bond energy and longer bond length than their oxides,leading to less structural damage,faster kinetics of electrochemical reactions,and better stability.The as-prepared Co-Cu bimetallic sulfides show enhanced electrochemical performance due to various valences of Co and Cu as well as the existence of S.As a result,aqueous Zn/CuCo_(2)S_(4) battery shows a high specific capacity of 117.4 mAh/g at 4 A/g and a good cycle life of over 8000 cycles.Based on PANa hydrogel electrolytes,a flexible Zn/CuCo_(2)S_(4) battery demonstrates excellent cycling stability.This battery can also meet the requirements of electronic devices with different shapes and performs well in extreme environments,such as freezing,drilling,and hammering.This work opens new avenues to obtain high-rate and long-life cathode materials for RAZBs by utilizing the synergistic effects of bimetallic sulfides and provides a new platform for flexible energy storage devices.
基金financially supported by the Science and Technology Project of Hunan Province (No. 2010FJ4061)the Technology Project of Changsha (No. K1201039-11)
文摘Al_2O_3-coated spinel LiMn_2O_4 cathode materials, presintered LiMn_2O_4(P-LMO), and calcined LiMn_2O_4(C-LMO) were synthesized by chemical deposition and thermal treating method using presintered and calcined LiMn_2O_4 as precursors. The crystal structure, morphology,the thickness of the coating layer, and particle size of prepared samples were investigated by X-ray diffraction(XRD), scanning electron microscopy(SEM), high-resolution transmission electron microscopy(HRTEM), and Malvern instruments. The average particle size of P-LMO with like-spheres(0.3 μm) is much smaller than that of C-LMO(0.5 μm). The Al_2O_3 layer of P-LMO can effectively reduce the charge transfer resistance and inhibit the Mn dissolution. The electrochemical performance of P-LMO is better than that of C-LMO. It is found that the LiMn_2O_4 cathode materials have excellent electrochemical cyclability by coated 2 mol% Al_2O_3 at the surface of presintered material. The initial discharge capacity of the material with 2 mol% Al_2O_3-coated is 114.0 m Ah·g^(-1) at 0.1 C rate and 55 ℃, and the capacity retention is 87.3 % at 0.5 C rate.
