纳米限制作为硬碳中用于钠储存的电解质状态选择器

摘要(中文译文)

钠离子电池是大规模储能的有前景候选者，但硬碳负极仍面临不可逆钠损失和阻抗增长的问题，这些问题源于早期电解液还原和不稳定的界面相形成。在此，我们明确了一个核心但常被忽视的观点：硬碳中的纳米限域不仅限制传输，还选择可及孔隙内的局部电解液状态。这种受限配位状态——由溶剂分离离子对、接触离子对和更大聚集体相对于本体电解液的平衡所定义——决定了去溶剂化、还原路径以及由此产生的界面相演化轨迹。这一观点通过聚焦局部电解液状态如何调控可及性、还原和界面相稳定性，补充了已有的储钠机制，包括层间插入、缺陷吸附和闭孔填充。以这种方式构建框架后，不同硬碳和电解液体系之间看似不一致的结果便可在共同基础上得到更好的解释。我们认为，在限域条件下，界面相的存续而非仅SEI厚度才是决定性标准，因为传输稳定性取决于在循环过程中保持电化学可及的孔隙通道。因此，将纳米限域视为电解液状态选择器，为理解和比较多孔硬碳中的储钠行为提供了一个可检验的概念框架。

Abstract

Sodium-ion batteries are promising candidates for large-scale energy storage, but hard-carbon anodes still suffer from irreversible sodium loss and impedance growth arising from early electrolyte reduction and unstable interphase formation. Here, we make explicit a central but often underdeveloped idea: nanoconfinement in hard carbon does not merely restrict transport but selects the local electrolyte state within accessible pores. This confined coordination regime, defined by the balance among solvent-separated ion pairs, contact ion pairs, and larger aggregates relative to the bulk electrolyte, governs desolvation, reduction pathways, and the resulting interphase trajectory. This viewpoint complements established sodium-storage mechanisms, including interlayer insertion, defect adsorption, and closed-pore filling, by focusing on how local electrolyte states regulate access, reduction, and interphase stability. Framed in this way, apparently inconsistent results across hard carbons and electrolyte families become more interpretable on a common basis. We argue that interphase survival, rather than SEI thickness alone, is the decisive criterion under confinement because transport stability depends on preserving electrochemically accessible pore pathways during cycling. Viewing nanoconfinement as an electrolyte-state selector therefore provides a testable conceptual framework for understanding and comparing sodium-storage behavior in porous hard carbons.

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