Deciphering Roles of Interfacial Tunable Primer for High Active Material Contents Pure Silicon Electrodes

While pure silicon (Si) is a highly attractive anode material for next-generation high-energy-density lithium-ion batteries, its practical implementation is limited by severe volumetric fluctuations during cycling. This intrinsic instability inevitably induces continuous structural degradation, strictly restricting the maximum allowable active material fraction within the electrode. To address this critical challenge, we design an interfacial tunable functional primer (fp) that serves as an effective multi-component bridging agent. By optimizing the mechanical resilience and electrochemical cohesion among electrode components, the fp layer dissipates interfacial stress and secures continuous electron conduction pathways. Furthermore, the unique ionophoric properties of the benzoxazine framework directly regulate the interfacial solvation structure and enhance ion flux. Driven by these integrated effects, the fp-modified Si anode achieves remarkable electrochemical reversibility even at a nearly binder-free composition containing 99 wt% active material content. This strategy completely averts the rapid physical degradation typically observed in standard binder networks under such extreme formulations. Furthermore, fp-modified Si demonstrates practical viability by assembling double-stacked pouch cells paired with NCM90 cathodes, which exhibit long-term cycle durability. This study provides a highly effective paradigm for electrode-component regulation and molecular-level engineering in pure Si anode interfacial modification strategies.