Hard carbon is regarded as a promising anode candidate for sodium-ion batteries due to its low cost, relatively low working voltage, and satisfactory specific capacity. However, it still remains a challenge to obtain a high-performance hard carbon anode from cost-effective carbon sources. In addition, the solid electrolyte interphase (SEI) is subjected to continuous rupture during battery cycling, leading to fast capacity decay. Herein, a lignin-based hard carbon with robust SEI is developed to address these issues, effectively killing two birds with one stone. An innovative gas-phase removal-assisted aqueous washing strategy is developed to remove excessive sodium in the precursor to upcycle industrial lignin into high-value hard carbon, which demonstrated an ultrahigh sodium storage capacity of 359 mAh g⁻¹. It is found that the residual sodium components from lignin on hard carbon act as active sites that controllably regulate the composition and morphology of SEI and guide homogeneous SEI growth by a near-shore aggregation mechanism to form thin, dense, and organic-rich SEI. Benefiting from these merits, the as-developed SEI shows fast Na⁺ transfer at the interphases and enhanced structural stability, thus preventing SEI rupture and reformation, and ultimately leading to a comprehensive improvement in sodium storage performance.

中文翻译：

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木质素衍生的硬碳阳极具有坚固的固体电解质界面，可提高钠存储性能

硬碳因其低成本、相对较低的工作电压和令人满意的比容量而被认为是钠离子电池的有前途的负极候选者。然而，从具有成本效益的碳源获得高性能硬碳阳极仍然是一个挑战。此外，固体电解质界面（SEI）在电池循环过程中会不断破裂，导致容量快速衰减。本文开发了一种具有强大SEI的木质素基硬碳来解决这些问题，有效地一石二鸟。开发了一种创新的气相去除辅助水洗策略，以去除前体中过量的钠，将工业木质素升级为高价值的硬碳，其表现出359 mAh g ^-1的超高钠存储容量。研究发现，硬碳上木质素残留的钠成分作为活性位点，可控地调节SEI的组成和形态，并通过近岸聚集机制引导SEI均匀生长，形成薄、致密且富含有机物的SEI。受益于这些优点，所开发的SEI在相间表现出快速的Na ⁺转移并增强了结构稳定性，从而防止了SEI破裂和重组，最终导致钠储存性能的全面改善。