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

【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(Li_1.2Mn_0.52Ni_0.2Co_0.08O₂)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 Ni³⁺)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.更多还原

【Abstract】 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_1.2Mn_0.52Ni_0.2Co_0.08O₂)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 Ni³⁺)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.更多还原