Zinc oxide-reinforced silicon anodes for high-performance all-solid-state lithium-ion batteries

Abstract

Silicon is a promising candidate as an anode material for all-solid-state lithium batteries (ASSLBs) due to its high theoretical specific capacity (∼3500 mAh g⁻¹), low cost and abundant earth reserves. Pioneering works find that the unique two-dimensional (2D) solid electrolyte interphase (SEI) layer formed between the pure Si electrode and solid-state electrolyte (SSE) can buffer the effect of the volume change of the Si anode; however, the poor kinetic performance of the Si anode caused by its lower Li⁺ diffusion coefficient and electronic conductivity still hinders its practical implementation. Herein, an Si–ZnO composite anode is prepared by introducing ZnO nanoparticles into commercial Si microsheets. ZnO spontaneously transforms into a Zn/Li₂O mixture during the initial electrochemical cycling with Li⁺. The formed Zn/Li₂O mixture with a mixed ion- and electron-conducting property enables the uniform lithium-ion flux distributions at interfaces, thereby improving the rate capability and cycling stability of the Si anode significantly. The Si–ZnO composite anode delivers a reversible capacity of 2349 mAh g⁻¹ at 0.1 A g⁻¹ and yields a discharge capacity of 1125 mAh g⁻¹ at a high rate of 5 A g⁻¹. Furthermore, ASSLBs based on the Si–ZnO anode exhibit superior rate capability and robust cycling performance.