Rigid-flexible double coating silicon oxide composed of pitch pyrolytic carbon and polyvinyl alcohol/polyethyleneimine/carbon nanotubes as high-performance anode material for lithium-ion battery

Silicon oxide (SiOx) is considered to be one of the most promising anodes of lithium-ion batteries for its advantageous capacity and abundant natural resources. However, the practical application of SiOx is facing great challenges due to its low conductivity and poor cycle performance. In order to accelerate the commercial application of SiOx, we constructed a pitch pyrolytic carbon rigid coating and a highly conductive polyvinyl alcohol/polyethyleneimine/carbon nanotubes (PVA/PEI/CNTs) flexible coating on the surface of micron-sized SiOx. The synergistic effect of the double coating enhances the conductivity of SiOx, reduces the strain stress caused by the volume change of SiOx, prevents the particles from breaking away from the current collector, and maintains the structural integrity of SiOx under long-term cycling. The obtained SiOx/E@CPPC anode exhibits high initial coulombic efficiency (73.91%), excellent cycle stability (645.8 mAh & BULL;g(-1) after 700 cycles at 0.5 A & BULL;g(-1)) and excellent rate performance (407.1 mAh & BULL;g(-1) at 5 A & BULL;g(-1)). The double coating makes SiOx/E@CPPC composites have a good application prospect in lithium-ion batteries.