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

SiO_x 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 SiO_x 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 SiO_x 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 SiO_x 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.