Mitigating Electrode Stress via Self-Constructed Interfacial Carrier Networks in High-Areal-Capacity SiO_x Anodes

SiOx is considered as a promising anode material for high-energy-density Li-ion batteries, benefiting from its moderate volume swelling and high theoretical capacity. However, the dramatic stress accumulation caused by heterogeneous lithiation kinetics makes the SiOx anode undergo fast capacity fading, especially at high mass loading (≥3.0 mg cm-2). Here, we construct a self-assembled interfacial carrier network for the SiOx anode (SiOCCu) to enhance interfacial lithiation dynamics and achieve effective stress relief. Through the conversion reaction of Cu2O, an in situ formed Li2O-rich interphase, integrated with a metallic Cu framework, constructs a dual ion-electron conductive network on the SiOx surface. Moreover, the Li2O layer regulates interfacial adsorption, guiding the formation of a robust, graded solid electrolyte interphase that simultaneously enhances interfacial Li+ transport and mechanical robustness. Benefiting from this architecture, the SiOCCu anode delivers an initial areal capacity of 11.68 mAh cm-2 at ultrahigh mass loading of 9.3 mg cm-2. The assembled Ah-level SiOCCu||NCM85 pouch cell achieves a maximum energy density of both 354.8 Wh kg-1 and 1367.4 Wh L-1, accompanied by capacity retention of 73.5% after 100 cycles. This work presents a feasible and scalable strategy for the practical design of large-volume-change electrodes with effective stress dissipation for high-energy-density batteries.