Solvothermal Mn-pretreatment enabling coupled defect and closed-pore regulation in hard carbon for sodium ion batteries

doi:10.1016/j.jechem.2026.07.069

Solvothermal Mn-pretreatment enabling coupled defect and closed-pore regulation in hard carbon for sodium ion batteries

2026-08-05

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DOI：10.1016/j.jechem.2026.07.069

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Hard carbon (HC) is a highly promising anode for sodium ion batteries, yet its performance strongly depends on the delicate balance among structural ordering, defect chemistry, and nanopore characteristics. Here, we report a solvothermal manganese (Mn)-pretreatment strategy to achieve coupled regulation of defect chemistry and closed-pore structure in HC. During the pretreatment, Mn species are introduced into the HC matrix and subsequently mediate carbon-layer rearrangement during high-temperature carbonization. This transient regulation restrains the overgrowth of graphitic domains, promotes the development of uniformly distributed closed nanopores, and suppresses electrochemically detrimental defects. Consequently, the HC framework is optimized with suitable interlayer spacing, abundant closed nanopores, and controlled defect density. The optimized HC delivers a reversible capacity of 340.7 mA h g−1 with an initial Coulombic efficiency of 86.0%, together with improved rate capability and cycling stability. Mechanistic analyses further reveal that the optimized structure facilitates diffusion-dominated plateau storage, accelerates Na+ transport, and induces the formation of a thinner and more homogeneous solid electrolyte interphase. This work provides an effective strategy for engineering advanced HC-based anodes for sodium ion batteries.

Keywords:

Hard carbon

Sodium ion batteries

Mn regulation

Graphitization

Closed nanopores

Solvothermal Mn-pretreatment enabling coupled defect and closed-pore regulation in hard carbon for sodium ion batteries

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