Layered Siloxene Microparticles: Unveiling Long-Term Stability and High Volumetric Capacity for Advanced Lithium-Ion Batteries

Two-dimensional (2D) Si π materials, a silicon counterpart of graphene, are particularly interesting because they exhibit intrinsic electrochemical and mechanical behavior combined with structural anisotropy. This work aims to improve the Li-storage performance of 2D siloxene (2DSi) microparticles by co-imidization with polymer binder. The proposed method combines 2DSi with poly(amic acid) to form a covalently bound poly(imide) (PI) layer upon thermal dehydration. Electrochemical evaluations reveal that the resulting 2DSi-PI electrode exhibits a unique electrochemical behavior toward Li+ based on intercalation, with additional reversible (de-)lithiation attributed to carbonyl oxygens of PI. Without suffering volume expansion, the 2DSi-PI electrodes display a highly stable capacity generation of 585 mAh/g at 250 mA g−1 with a capacity loss of 0.13 % per cycle at the 200th cycle. In addition, the full-cell of the 2DSi-PI electrode combined with the LiNi0.8Co0.1Mn0.1O2 cathode achieves an energy density of 426 Wh kg−1 at a power density of 1,155 W kg−1. Ex-situ and theoretical analyses of the (de-)lithiated 2DSi-PI electrodes demonstrate that the surface-bound PI suppresses solvent reduction, increases the amount of LiF in the SEI layer, and improves the binding affinity of 2DSi to LiF. As a result, the cycle stability of 2DSi-PI electrodes is significantly improved in comparison to 2DSi-polyvinylidene fluoride electrodes. Co-imidization with PI emerges as a promising strategy for advancing the electrochemical properties of 2DSi electrodes, offering insights for the design of high-performance lithium-ion battery anodes.