Harnessing Thermodynamic Decoupling in Ion Intercalation Chemistry to Unlock Unprecedented Energy Storage

ABSTRACT Reversible ion intercalation chemistry underpins rocking‐chair batteries and smart ionic switching devices. Conventional intercalation activation relies on ion‐host distance and electronegativity, confining regulations to stress‐release dimension in carbon and silicon‐based materials associated with high expansion and mechanical degradation. However, this paradigm fails in regulating low‐expansion materials for mitigating degradation, because stress arising from the constrained volume blocks functional intercalation. Herein, we harness ion‐host binding strength derived from thermodynamic decoupling as a widely applicable intercalation activation dimension, whose regulation can be realized by transferring electrons to host low‐energy orbital, and thus propose two quantitative descriptors to coordinate the antagonistic conflict between the binding strength and phase stability. Accordingly, we provide three types of cases to demonstrate its utility and applications, ranging from commercial carbon‐based electrodes to intractable covalent nitrides. The consideration of ion‐host binding strength sheds light on why graphite accommodates Li‐ but not Na‐ion. α‐VSi ₂ N ₄ prototype tuned from M Si ₂ N ₄ ( M = Transition metal) family achieves a Na‐ion capacity of 163 mAh g ⁻¹ with merely 5.6% expansion, surpassing the near‐zero‐expansion Na ₄ Ti ₅ O ₁₂ benchmark by over 30%. This work establishes the intercalation chemistry activation landscape by exploring unprecedented regulation dimension, broadening the scope for the selective design of energy storage materials and beyond.