Double-shell Li-rich layered oxide hollow microspheres with sandwich-like carbon@spinel@layered@spinel@carbon shells as high-rate lithium ion battery cathode

摘要

Li-rich layered oxides (LRLO) with high specific capacity over 250 mA h g(-1) are attractive cathode material candidates for the next-generation high performance lithium-ion batteries. However, LRLO always suffers from low initial Coulombic efficiency, poor cycling and rate properties. Herein, unique double-shell LRLO hollow microspheres with sandwich-like carbon@spinel@layered@spinel@carbon shells (LRLO-500@S@C) were successfully synthesized via a facile template-free method, followed by carbothermal reduction treatment. The fabricated LRLO-500@S@C cathode delivers a high initial charge capacity of 312.5 mA h g(-1 )with a large initial Coulombic efficiency of 89.7%. After cycling 200 times, large and stable discharge capacities of 228.3 mA h g(-1) and 196.1 mA h g(-1) can be obtained at 1.0 C and 5.0 C, respectively. Moreover, coin-type full cell with LRLO-500@S@C as cathode and Li(4)Ti(5)O(12 )as anode delivers outstanding lithium storage properties. The impressive electrochemical performances of LRLO-500@S@C cathode material can be attributed to its multiscale co-ordinated design based on hierarchical double-shell hollow construction, the special layered@spinel@carbon heterostructured shells and the introduced oxygen vacancies, which benefit to shorten Li-ion diffusion paths, strengthen structural stability and reduce side reactions.