Theoretical Assistant Experimental Optimization for Advanced All-Solid-State Sodium Batteries

ConspectusAll-solid-state sodium batteries (ASSSBs) are indispensable components as alternatives to balance the energy structure owing to high energy density, high safety, and high resource abundance. The innovation of ASSSBs technology not only eliminates the safety risks of leakage/combustion associated with traditional liquid electrolytes but also enables the energy density to reach 200 Wh kg^-1. Furthermore, the energy density can potentially exceed 300 Wh kg^-1 by adopting an anode-free architecture design, significantly expanding its application potential in fields such as electric vehicles and smart grids. However, their development faces critical challenges such as low ionic conductivity in solid-state electrolytes (SSEs), high interface impedance between SSEs and electrodes, significant volume changes in materials during cycling, and detrimental interfacial reactions. The larger ionic radius of Na⁺ leads to sluggish migration within solid-state matrices, while imperfect physical contact at solid-solid interfaces increases impedance and risks dendrite formation. Structural deformation of electrode materials during cycling further destabilizes interfaces. These multiscale complexities are difficult to resolve through experimental trial-and-error alone. Therefore, theoretical computational approaches, such as molecular dynamics simulations to unravel ion transport mechanisms, first-principles calculations to predict material stability, and machine learning (ML) to accelerate high-performance SSEs screening, provide critical insights for precise interface design and material optimization, thereby advancing the practical realization of ASSSBs. In light of these findings, we emphasize the integration of theoretical calculations and experimental approaches to deepen the understanding and accelerate the development of ASSSBs. First, the foundation and design principle of ASSSBs are presented briefly. Subsequently, the fundamental theories and verification modes for ASSSBs are reviewed systematically. Notably, we meticulously discuss the combination of theoretical calculations and experimental findings for key components of ASSSBs, including SSEs, cathodes, anodes, and their interface engineering. Specific aspects covered include interface compatibility between SSEs and high-voltage cathodes, interfacial formation energies between SSEs and anodes, transport mechanisms of Na⁺ across interfaces, and molecular dynamics simulations of polymer SSE/Na anode interfaces. Finally, we comprehensively outline prevailing challenges and future prospects, charting a course for the next generation of high-performance ASSSBs.