An ultrahigh-areal-capacity SiOx negative electrode for lithium ion batteries

Constructing a stable microstructure is highly crucial in promoting the practical applications of Si-based negative electrodes, addressing the issues of huge volume change and unstable solid electrolyte interface (SEI). Herein, an integrated electrode structure is developed based on micro-sized SiO particles by bilayers coating of carbon and poly(3,4-ethylene dioxythiophene) (PEDOT) with carbon nanotube/Super P conductive network in-situ embedded (SiO@C@P_CS). The as-prepared SiO@C@P_CS negative electrode exhibits high Coulombic efficiency reaching 99.9% and capacity retentions of 86.7% (1019 mAh g) after 1000 cycles at 750 mA g and 98.4% (973 mAh g) after 400 cycles at 1500 mA g (with a commercial-level areal capacity of 2.57 mAh cm). The excellent long cycling capability is further evidenced both in half cell with ultrahigh areal capacity up to 11.75 mAh cm at the mass loading of 8.66 mg cm and Li[NiCoMn]O (NCM811)||SiO@C@P_CS full cell with commercial loading. The improved electrochemical performance is attributed to the synergistic effects of the bilayers. This study offers a facile solution to the challenges facing alloying-type negative electrode materials with huge volume changes by confining volume change, enhancing electric conductivity, and isolating the growth of SEI to promote their practical uses.