The development of strategies to inhibit structural degradation and surface side reactions is the key to promoting the large-scale application of lithiumrich manganese-based cathode materials Li_(1.2)Mn_(0.54)Ni_(0.13...The development of strategies to inhibit structural degradation and surface side reactions is the key to promoting the large-scale application of lithiumrich manganese-based cathode materials Li_(1.2)Mn_(0.54)Ni_(0.13)Co_(0.13)O_(2)(LMNCO).Herein,LMNCO was triply modified from the inside to the outside,by bulk doping of Mo6+,fabricating oxygen vacancies(OVs)defects,and surface coating of S,N-doped carbon nanolayers(SNCN).The integration of Mo6+doping and OVs defects widens and stabilizes the Li+diffusion channel,and the surface coating of SNCN provides additional electrons for LMNCO in the conduction band region,achieving a simultaneous improvement in both ionic and electronic conductivity.Meanwhile,Mo^(6+)doping and OVs mitigate the irreversible phase transitions caused by oxygen loss and transition metal(TM)out-of-plane migration,while SNCN inhibits the corrosion of the electrolyte on the material surface and enhances the stability of the surface structure.Benefiting from the synergistic effect of these modifications,the structural evolution of the modified material is highly reversible,and the layered structure remains intact during repeated lithiation/delithiation processes,while the mechanical properties of material are also improved,effectively suppressing crack generation and TM dissolution.As a result,at room temperature(25℃),the modified cathode demonstrates a high capacity retention of 94.6%after 200 cycles at 1 C,and a high rate capacity of 161.0 mAh·g^(-1) at 5 C.Especially,under harsh conditions,the capacity retention is 76.3%after 150 cycles at 55℃ and 1 C.This work provides a new solution for developing advanced LMNCO cathode materials.展开更多
以改进Hummers法制备的氧化石墨烯作为载体,运用简单化学沉积并加以热处理制备硫/氧化石墨烯(H-GO/S)复合材料。采用傅里叶红外光谱仪(FT-IR)、X线衍射仪(XRD)、透射电子显微镜(TEM)、热质量分析仪(TGA)等表征手段对H-GO/S复合材料的微...以改进Hummers法制备的氧化石墨烯作为载体,运用简单化学沉积并加以热处理制备硫/氧化石墨烯(H-GO/S)复合材料。采用傅里叶红外光谱仪(FT-IR)、X线衍射仪(XRD)、透射电子显微镜(TEM)、热质量分析仪(TGA)等表征手段对H-GO/S复合材料的微观结构、形貌和组成进行表征;同时运用恒流充放电和循环伏安对电极材料进行电化学性能测试。在0.1 C倍率下H-GO/S复合材料首次放电比容量达1 060 m A·h/g,20次循环之后,放电比容量趋向稳定,160次循环后放电比容量仍可达到620 m A·h/g,衰减率仅为0.068%,库伦效率始终保持在97%以上。以上结果表明H-GO/S复合材料具有优良的循环稳定性以及比较高的库伦效率。展开更多
基金supported by Key Research and Development Program of Gansu(No.24YFGA025)Joint Research Foundation of Gansu(No.21JRRA832)+1 种基金the National Natural Science Foundation of China(No.22269012)Gansu Provincial Department of Education:Graduate Student“Innovation Star”Project(No.2025CXZX532).
文摘The development of strategies to inhibit structural degradation and surface side reactions is the key to promoting the large-scale application of lithiumrich manganese-based cathode materials Li_(1.2)Mn_(0.54)Ni_(0.13)Co_(0.13)O_(2)(LMNCO).Herein,LMNCO was triply modified from the inside to the outside,by bulk doping of Mo6+,fabricating oxygen vacancies(OVs)defects,and surface coating of S,N-doped carbon nanolayers(SNCN).The integration of Mo6+doping and OVs defects widens and stabilizes the Li+diffusion channel,and the surface coating of SNCN provides additional electrons for LMNCO in the conduction band region,achieving a simultaneous improvement in both ionic and electronic conductivity.Meanwhile,Mo^(6+)doping and OVs mitigate the irreversible phase transitions caused by oxygen loss and transition metal(TM)out-of-plane migration,while SNCN inhibits the corrosion of the electrolyte on the material surface and enhances the stability of the surface structure.Benefiting from the synergistic effect of these modifications,the structural evolution of the modified material is highly reversible,and the layered structure remains intact during repeated lithiation/delithiation processes,while the mechanical properties of material are also improved,effectively suppressing crack generation and TM dissolution.As a result,at room temperature(25℃),the modified cathode demonstrates a high capacity retention of 94.6%after 200 cycles at 1 C,and a high rate capacity of 161.0 mAh·g^(-1) at 5 C.Especially,under harsh conditions,the capacity retention is 76.3%after 150 cycles at 55℃ and 1 C.This work provides a new solution for developing advanced LMNCO cathode materials.
文摘以改进Hummers法制备的氧化石墨烯作为载体,运用简单化学沉积并加以热处理制备硫/氧化石墨烯(H-GO/S)复合材料。采用傅里叶红外光谱仪(FT-IR)、X线衍射仪(XRD)、透射电子显微镜(TEM)、热质量分析仪(TGA)等表征手段对H-GO/S复合材料的微观结构、形貌和组成进行表征;同时运用恒流充放电和循环伏安对电极材料进行电化学性能测试。在0.1 C倍率下H-GO/S复合材料首次放电比容量达1 060 m A·h/g,20次循环之后,放电比容量趋向稳定,160次循环后放电比容量仍可达到620 m A·h/g,衰减率仅为0.068%,库伦效率始终保持在97%以上。以上结果表明H-GO/S复合材料具有优良的循环稳定性以及比较高的库伦效率。
