Understanding De-protonation Induced Formation of Spinel Phase in Li-rich Layered Oxides for Improved Rate Performance  

作　　者：李保云 李广社 张丹 范建明 冯涛 李莉萍 

机构地区：[1]State Key Laboratory of Inorganic Synthesis & Preparative Chemistry, Jilin University [2]Key Laboratory of Design and Assembly of Functional Nanostructures, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences

出　　处：《Chinese Journal of Structural Chemistry》2018年第11期1723-1736,共14页结构化学（英文）

基　　金：financially supported by NSFC(No.21571176,21611530688,21771171,21671077 and 21025104)

摘　　要：Constructing layered-spinel composites is important to improve the rate performance of lithium-rich layered oxides.However,up to now,the effect of microstructure of composites on the rate performance has not been well investigated.In this study,a series of samples were prepared by a simple protonation and de-protonation for the pristine layered material(LiMnNiCoO)obtained by sol-gel method.The characterizations of XRD,Raman and oxidation-reduction potentials of charge-discharge curves demonstrated that these samples after de-protonation are layered-spinel composites.When these composites were tested as a cathode of lithium-ion batteries,the sample treated with 0.1 M of nitric acid exhibited higher discharge capacities at each current density than that of other composites.The outstanding rate performance is attributed to the high concentration of conduction electron resulting from the low average valence state(44.2%of Ni)as confirmed by its high conductivity(1.124×10??mat39800Hz)and ambient temperature magnetic susceptibility(8.40×10emu/Oe?mol).This work has a guiding significance for the synthesis of high rate performance of lithium battery cathode materials.Constructing layered-spinel composites is important to improve the rate performance of lithium-rich layered oxides.However,up to now,the effect of microstructure of composites on the rate performance has not been well investigated.In this study,a series of samples were prepared by a simple protonation and de-protonation for the pristine layered material(Li_(1.2)Mn_(0.52)Ni_(0.2)Co_(0.08)O_2)obtained by sol-gel method.The characterizations of XRD,Raman and oxidation-reduction potentials of charge-discharge curves demonstrated that these samples after de-protonation are layered-spinel composites.When these composites were tested as a cathode of lithium-ion batteries,the sample treated with 0.1 M of nitric acid exhibited higher discharge capacities at each current density than that of other composites.The outstanding rate performance is attributed to the high concentration of conduction electron resulting from the low average valence state(44.2%of Ni^(3+))as confirmed by its high conductivity(1.124×10^(-2)?^(-1)?m^(-1) at39800Hz)and ambient temperature magnetic susceptibility(8.40×10^(-3) emu/Oe?mol).This work has a guiding significance for the synthesis of high rate performance of lithium battery cathode materials.

关 键 词：protonation and de-protonation layered-spinel composites rate performance conduction electron 

分 类 号：TQ[化学工程]