A highly stable SiO_x-based anode enabled by self-assembly with polyelectrolyte

Silicon-based materials with high specific capacities have attracted great attentions as an alternative to graphite anode in lithium-ion batteries. However, the low electrical conductivity and inefficient suppression of volume expansion make it somewhat unsuitable for practical applications. Thence, a rapid self-encapsulating approach was first adopted to construct a conductive and effective carbon protective shell on the surface of layered SiO_x-based nanosheets by compositing polyelectrolyte (polyethyleneimine, PEI) with graphene oxide (GO). This designed composite electrode has a compact and robust interfacial structure attributed to chemical integration and electrostatic interactions, which also greatly increased the tap density of the electrode. As an anode material, it delivered a high reversible capacity of 867 mAh g⁻¹ and excellent rate capability. The cycling stability is also retained even after rate performance test, which resulted a −0.033% capacity decay rate for each cycle in 500 cycles.