Selective incorporation of inorganic solid-electrolyte interphase into carbon-coated silicon nanoparticle anode for lithium-ion batteries with improved cyclic stability

Prelithiation is a crucial strategy for scalable lithium-ion batteries (LIB) that not only compensates for lithium (Li) loss but also prevents the formation of undesired solid-electrolyte interphase (SEI) layer. Depending on how the SEI is cultivated, it may incur either a positive or negative effect on the battery performance. In this work, we present a means of selectively incorporating inorganic SEI via chemical prelithiation and subsequent vacuum drying processes in ambient atmospheric conditions. The SEI layer is then used as a filler to reinforce the carbon layer coating silicon anode material in LIBs. Our employed pore-filling strategy effectively reduces the specific surface area and increases the mechanical strength of the carbon-coated silicon anode, resulting in simultaneous improvements in specific capacity and cell stability. In particular, Li-ions incorporated into nanovoids within the carbon layer are spontaneously converted to lithium hydroxide (LiOH) upon exposure to ambient moisture and then crystallize through vacuum drying. In addition, due to the increased compressive strength provided by the mechanical reinforcement effect in the LiOH-incorporated carbon coating layer, the cyclic stability of the cells increases from 29.2% to 76.5% after 100 cycles in comparison to bare silicon anodes. The rate capability is also improved by the high Li-ion diffusivity in LiOH. Therefore, these findings suggest that this approach to controlling the phase of SEI may have implications for the development of next-generation Li-ion batteries with high energy density and operational stability.