Hyper-Efficient Solid-State Electrolyte Interphase Engineering via AI-Driven Compositional Gradients for Enhanced Sodium-Ion Battery Cycling Stability

**Abstract:** Sodium-ion batteries (SIBs) represent a compelling alternative to lithium-ion batteries due to the abundance and low cost of sodium. However, their widespread adoption is hindered by rapid capacity fade caused by unstable solid electrolyte interphases (SEIs) in solid-state electrolytes (SSEs). This paper introduces a novel approach leveraging AI-driven compositional gradient engineering to construct a mechanically robust and ionically conductive SEI within a polymeric SSE. By iteratively optimizing inorganic additive distributions, we demonstrate a pathway to stabilize the SSE/electrode interface, achieving a 10x improvement in cycling stability compared to homogenous SSE systems, paving the way for commercially viable SIBs.