Solid-State Construction of CuO–Cu2O@C with Synergistic Effects of Pseudocapacity and Carbon Coating for Enhanced Electrochemical Lithium Storage

The pseudocapacitive effect can improve the electrochemical lithium storage capacity at high-rate current density. However, the cycle stability is still unsatisfactory. To overcome this issue, a multivalent oxide with a carbon coating represents a plausible technique. In this work, a CuO-Cu₂O@C composite has been constructed by a one-step bilayer salt-baking process and utilized as anode material for lithium-ion batteries. At a current density of 2.0 A g^-1, the as-prepared composite delivered a stable discharge capacity of 431.8 mA h g^-1 even after 600 cycles. The synergistic effects of the multivalence, the pseudocapacitive contribution from copper, and the carbon coating contribute to the enhanced electrochemical lithium storage performance. Specifically, the existence of cuprous suboxide improves the electrochemical conductivity, the pseudocapacitive effect enhances the lithium storage capacity, and the presence of carbon ensures cycle stability. The testing results show that CuO-Cu₂O@C composite has broad application prospects in portable energy storage devices. The present work provides an instructive precedent for the preparation of transition metal oxides with controllable electronic states and excellent electrochemical performance.