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 (SiO x ) 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 SiO x is facing great challenges due to its low conductivity and poor cycle performance. In order to accelerate the commercial application of SiO x , 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 SiO x . The synergistic effect of the double coating enhances the conductivity of SiO x , reduces the strain stress caused by the volume change of SiO x , prevents the particles from breaking away from the current collector, and maintains the structural integrity of SiO x under long-term cycling. The obtained SiO x /E@CPPC anode exhibits high initial coulombic efficiency (73.91%), excellent cycle stability (645.8 mAh·g −1 after 700 cycles at 0.5 A·g −1 ) and excellent rate performance (407.1 mAh·g −1 at 5 A·g −1 ). The double coating makes SiO x /E@CPPC composites have a good application prospect in lithium-ion batteries.