Coupling Network Reconstruction-Driven Charge Transport Transition: Capacity Breakthrough and Wide-Temperature Sodium Storage in Na₃VCr(PO₄)₃ Cathodes

NASICON-type sodium-ion batteries (SIBs) cathode material Na₃VCr(PO₄)₃ (NVCP) theoretically offers the advantage of high energy density. However, its practical capacity is severely restricted, rendering the theoretical potential unrealized. The root cause underlying this capacity limitation remains unclear to date, posing a fundamental obstacle to the material's practical application. Through the deep synergy of theoretical calculations and experiments, this study reveals that the electron state localization induced by insufficient V-Cr d-d orbital hybridization in NVCP is the core bottleneck constraining the intrinsic kinetics of charge transfer. To address this, we propose a "coupling network modulation" strategy, employing Mo⁶⁺ with a 4d⁰ empty orbital as a probe to implement precise intervention in the local bonding environment. The preferential occupation of Mo⁶⁺ at the Cr site efficiently reconstructs the Cr-O-V bonding topology and enhances V–Cr orbital overlap, boosting the bulk electronic conductivity by two orders of magnitude. Simultaneously, the strong covalent Mo–O bonds pin the lattice framework, significantly improving strain resistance and effectively suppressing structural degradation during long-term cycling. Consequently, the optimized Na_2.91VCr_0.97Mo_0.03(PO₄)₃ delivers an initial specific capacity of 105.2 mAh g^-1, achieving a 21.1% gain in specific energy, and exhibits excellent performance across a wide temperature range of -60 to 50 °C. This work clarifies the root cause of NVCP performance failure at the electronic structure level. It thereby establishes a novel strategy for performance modulation based on local bonding reconstruction, offering theoretical guidance for designing high-energy and wide-temperature SIBs cathode.