The Li_(4)Ti_(5)O_(12)(LTO)spinel material,ranking at the second large market share after graphite,is a promising anode material for lithium-ion batteries due to its good cycle stability,rate capability,and safety wit...The Li_(4)Ti_(5)O_(12)(LTO)spinel material,ranking at the second large market share after graphite,is a promising anode material for lithium-ion batteries due to its good cycle stability,rate capability,and safety with both conventional and low-temperature electrolytes.However,several critical challenges,such as the low capacity and gassing issue,hindered the wide applications of LTO anode.Recent progress indicated that the LTO performances are possible to be further improved by novel strategies,such as heterogeneous phase control,surface engineering,or overlithiation.To rethink and develop advanced LTO anodes,this review intensively associates the performances and modification strategies with the electronics/crystal structures.From a thermodynamic/kinetic point of view,we summarized the data obtained from recently developed characterization techniques,and the results of electrochemical performances and fundamental structures of LTO to potentially address several key challenges and issues toward advanced LTO anodes.As a result,light is shed on the future research direction of the LTO anodes.展开更多
Pure, layered compounds of overlithiated Li1＋xNi0.8Co0.2O2（x = 0.05 and 0.1） were successfully prepared by a modified combustion method. XRD studies showed that cell parameters of the material decreased with increa...Pure, layered compounds of overlithiated Li1＋xNi0.8Co0.2O2（x = 0.05 and 0.1） were successfully prepared by a modified combustion method. XRD studies showed that cell parameters of the material decreased with increasing the lithium content. SEM revealed that the morphology of particles changed from rounded polyhedral-like crystallites to sharp-edged polyhedral crystals with more doped lithium. EDX showed that the stoichiometries of Ni and Co agrees with calculated synthesized values. Electrochemical studies revealed the overlithiated samples have improved capacities as well as cycling behavior. The sample with x = 0.05 shows the best performance with a specific capacity of 113.29 mA.h.g-1 and the best capacity retention of 92.2% over 10 cycles. XPS results showed that the binding energy of Li ls is decreased for the Li doped samples with the smallest value for the x = 0.05 sample, implying that Li＋ ions can be extracted more easily from Li1.05Ni0.8Co0.2O2 than the other stoichiometries accounting for the improved performance of the material. Considerations of core level XPS peaks for transition metals reveal the existence in several oxidation states. However, the percentage of the＋3 oxidation state of transition metals for the when x = 0.1 is the highest and the availability for charge transition from the ＋3 to＋4 state of the transition metal during deintercalation is more readily available.展开更多
基金National Natural Science Foundation of China,Grant/Award Numbers:21875284,22075320,52073161National Science and Technology Major Project,Grant/Award Numbers:2019YFA0705703,2019YFE0100200Tsinghua University Initiative Scientific Research Program,Grant/Award Number:2019Z02UTY06。
文摘The Li_(4)Ti_(5)O_(12)(LTO)spinel material,ranking at the second large market share after graphite,is a promising anode material for lithium-ion batteries due to its good cycle stability,rate capability,and safety with both conventional and low-temperature electrolytes.However,several critical challenges,such as the low capacity and gassing issue,hindered the wide applications of LTO anode.Recent progress indicated that the LTO performances are possible to be further improved by novel strategies,such as heterogeneous phase control,surface engineering,or overlithiation.To rethink and develop advanced LTO anodes,this review intensively associates the performances and modification strategies with the electronics/crystal structures.From a thermodynamic/kinetic point of view,we summarized the data obtained from recently developed characterization techniques,and the results of electrochemical performances and fundamental structures of LTO to potentially address several key challenges and issues toward advanced LTO anodes.As a result,light is shed on the future research direction of the LTO anodes.
文摘Pure, layered compounds of overlithiated Li1＋xNi0.8Co0.2O2（x = 0.05 and 0.1） were successfully prepared by a modified combustion method. XRD studies showed that cell parameters of the material decreased with increasing the lithium content. SEM revealed that the morphology of particles changed from rounded polyhedral-like crystallites to sharp-edged polyhedral crystals with more doped lithium. EDX showed that the stoichiometries of Ni and Co agrees with calculated synthesized values. Electrochemical studies revealed the overlithiated samples have improved capacities as well as cycling behavior. The sample with x = 0.05 shows the best performance with a specific capacity of 113.29 mA.h.g-1 and the best capacity retention of 92.2% over 10 cycles. XPS results showed that the binding energy of Li ls is decreased for the Li doped samples with the smallest value for the x = 0.05 sample, implying that Li＋ ions can be extracted more easily from Li1.05Ni0.8Co0.2O2 than the other stoichiometries accounting for the improved performance of the material. Considerations of core level XPS peaks for transition metals reveal the existence in several oxidation states. However, the percentage of the＋3 oxidation state of transition metals for the when x = 0.1 is the highest and the availability for charge transition from the ＋3 to＋4 state of the transition metal during deintercalation is more readily available.
