Dual-scale structure engineering synergy enables high-areal-capacity and stable lithium-ion battery anodes

The flourishing electrode materials such as metal oxides have been considered as potential substitutes for next generation lithium-ion batteries (LIBs). However, large stress concentration and inferior mass transfer upon repeated lithiation/delithiation severely compromises the structural integrity of the electrode, especially for high loading thick electrodes. In this work, inspired by the robust bionic thorny structure, we propose a dual-scale structural strategy that integrates macro-architecture with micro-interface to develop a unique yet stable 3D hollow-thorny Cu_xO/Cu electrode (3D HT-Cu_xO/m-Cu) with stable internal current collector-active material and exterior solid electrolyte interphase (SEI) interfaces. The dense and robust hollow-thorny structure endows the electrode with rapid mass transfer and stress buffering effect that can promote the reaction kinetics. More importantly, the inner semi-coherent Cu-Cu_xO interface enables exceptional structural stability and electronic conductivity of the electrode, whereas the exterior inorganic LiF-rich SEI contributes to unblocked Li⁺ transport. Therefore, the designed 3D HT-Cu_xO/m-Cu electrode exhibits outstanding Li⁺ diffusion capability (1.25 × 10^-12 cm² s^-1). A high areal capacity of 1.84 mAh cm^-2 is achieved even after 250 cycles at 1 mA cm^-2. This study presents a powerful dual-structure engineering strategy to simultaneously mitigate stress concentrations and enhance mass transport, enabling advanced electrodes beyond LIBs.