Synthesis of a novel porous silicon microsphere@carbon core-shell composite via in situ MOF coating for lithium ion battery anodes

Nanostructured silicon/carbon composites with enhanced lithium storage are especially attractive for lithium-ion batteries (LIBs). The SiAl/Al-MOF core-shell precursor is prepared by the self-corrosion reaction of SiAl alloy with an organic acid in the hydrothermal condition, and the following rational annealing and etching treatments lead to the formation of the porous silicon microsphere@C (pSiMS@C) core-shell composite. The pSiMS@C composite is composed of an amorphous carbon shell and the porous silicon microsphere core consisting of interconnected nanowires, manifesting a novel core-shell structure. The as-prepared pSiMS@C electrode delivers a reversible capacity of 1027.8 mAh g(-1) after 500 cycles at 1 A g(-1), with a good capacity retention of 79%. The carbon shell may markedly improve the electronic conductivity, and the porous silicon microsphere core may promote the kinetics for Faradic reaction and diffusion process and alleviate the huge volume change during the charge/discharge cycling, responsible for the excellent lithium storage performance of the pSiMS@C core-shell composite.