Enhancing Low-Pressure Operability of Si Anodes in All-Solid-State Batteries Through Interlayer Engineering and Prelithiation

The growing demand for vehicle electrification and energy storage systems has spurred research on high-energy-density lithium-ion batteries (LIBs). Solidifying electrolytes using inorganic materials has gained interest due to its potential to enhance energy density and safety. However, challenges, such as dendritic growth and limited Li⁺ diffusion, have impeded the integration of Li metal anodes (LMAs) in all-solid-state batteries (ASSBs). Si anodes, not constrained by the same issues, could present an advantageous alternative. However, in LIBs, Si anodes undergo severe volume changes (&gt;300%) during charge-discharge cycles, leading to fractures and a loss of electrical connectivity. To overcome this, Si is often electrically wired with nanostructured carbonaceous materials like carbon nanotubes (CNTs) and graphene. While this strategy can also be applied to ASSBs, it raise concerns about adverse reactions between carbon materials and SEs. Recent studies reported that the performance of Si ASSBs could be enhanced by eliminating solid electrolytes and carbon additives in Si electrodes, demonstrating 80% capacity retention after 500 cycles at 50 MPa. This performance is attributed to the mechanically sintering ability of lithiated Si and the lack of destructive side reactions. However, the high operating pressures used need to be addressed for practical applications.<br/>In our study, we present a comprehensive Si ASSB design incorporating a thin metallic interlayer at the Si electrode-SEs interface and integrating the Si electrodes with CNTs. This interlayer allows Li⁺ transport maintenance across the interface despite the dimensional changes of Si anode, demonstrating improved performance of ASSBs under low-pressure conditions.<br/><br/>[1] H. S. Tan Darren et al., <i>Science</i> <b>2021</b>, <i>373</i>, 1494.<br/>[2] D. H. Kim et al., <i>J. Power Sources</i> <b>2019</b>, <i>426</i>, 143-150.