Molecular-level interface engineering of VSe2 self-supporting architectures enables durable Mg2+/Li+ co-intercalation

The urgent demand for sustainable and efficient energy storage has spurred interest in magnesium-lithium hybrid-ion batteries (MLHB), which combine the safety and cost-effectiveness of magnesium (Mg) anodes with the superior ion transport properties of lithium. However, the development of MLHB is hindered by the limitations of conventional cathode materials, including structural instability and high intercalation energy barriers. Here, we present a novel cathode architecture based on vanadium diselenide (VSe2), synthesized via atmospheric pressure chemical vapor deposition (APCVD). This approach enables the direct growth of VSe2 nanoarchitectures on carbon nanotube film (CNTf) current collectors, ensuring excellent electron transport and mechanical robustness. Meanwhile, a conformal poly(3,4-ethylenedioxythiophene) (PEDOT) coating is strategically engineered onto the VSe2 cathode surface through molecularly precise interfacial manipulation, which significantly enhances the mechanical toughness of the cathode, thereby alleviating stress concentration and preventing mechanical degradation. These are systematically validated by finite element modeling and advanced microscopy. Density functional theory (DFT) calculations and experiments reveal that pre-lithiation significantly improves electronic conductivity and facilitates Mg2+ insertion. The resulting VSe2-based cathode exhibits outstanding electrochemical performance, achieving a specific capacity of 129 mAh g−1 at 2000 mA g−1 and maintaining 107.3 mAh g−1 over 3000 cycles at 1000 mA g−1, demonstrating remarkable cycling stability. This work establishes a scalable strategy for MLHB cathodes, advancing the frontier of multivalent-ion battery technology.