Formulating Electron Beam‐Induced Covalent Linkages for Stable and High‐Energy‐Density Silicon Microparticle Anode

High‐capacity silicon (Si) materials hold a position at the forefront of advanced lithium‐ion batteries. The inherent potential offers considerable advantages for substantially increasing the energy density in batteries, capable of maximizing the benefit by changing the paradigm from nano‐ to micron‐sized Si particles. Nevertheless, intrinsic structural instability remains a significant barrier to its practical application, especially for larger Si particles. Here, a covalently interconnected system is reported employing Si microparticles (5 µm) and a highly elastic gel polymer electrolyte (GPE) through electron beam irradiation. The integrated system mitigates the substantial volumetric expansion of pure Si, enhancing overall stability, while accelerating charge carrier kinetics due to the high ionic conductivity. Through the cost‐effective but practical approach of electron beam technology, the resulting 500 mAh‐pouch cell showed exceptional stability and high gravimetric/volumetric energy densities of 413 Wh kg−1, 1022 Wh L−1, highlighting the feasibility even in current battery production lines. The integration of 5 µm silicon microparticle (SiMP) and elastic gel polymer electrolyte is achieved through electron beam irradiation. The interconnected system provided intertwined covalent linkages on the inside/outside of the SiMP, enabling stable cell operation with exceptional gravimetric/volumetric energy densities of 413 Wh kg−1 and 1022 Wh L−1 even in a 500 mAh‐pouch cell.