Enabled ternary synergistic mechanochemical activation of boron-rich carbon-oxygen hybrid frameworks for high-performance lithium-ion and sodium-ion batteries

Hard carbon is currently the most widely used anode material for sodium-ion batteries (SIBs), but its practical application is still limited by low Coulombic efficiency and the difficult trade-off between high capacity and low-cost production. As a light element, boron is an attractive candidate for SIB anodes owing to its high theoretical capacity, low cost, and non-toxicity. However, boron has shown intrinsically low Na-storage activity in previous studies. Herein, we propose a ternary synergistic activation strategy to activate the electrochemical Na-storage activity of a boron-rich carbon‑oxygen hybrid composite. In the hybrid network, synergistic B–O–C and B–C bonds construct a continuous three-dimensional framework that integrates high electronic conductivity, strong ion affinity, abundant defect sites, and hierarchical mesoporosity, thereby providing sufficient active sites and fast ion-transport pathways. Benefiting from this activation strategy, the boron-rich carbon‑oxygen hybrid framework (BBaC) delivers a high reversible capacity of 333.4 mAh g −1 and excellent rate capability (107.8 mAh g −1 at 4.0 A g −1 ) in SIBs, together with excellent cycling stability over 800 cycles. Notably, BBaC also exhibits superior electrochemical performance in lithium-ion batteries. This work provides a new ternary synergistic activation strategy for developing boron-rich composites as advanced anode materials for alkali-ion batteries.