Hard carbons are emerging as the most viable anodes to support the commercialization of sodium-ion (Na-ion) batteries due to their competitive performance. However, the hard carbon anode suffers from low initial Coulombic efficiency (ICE), and the ambiguous Na-ion (Na⁺) storage mechanism and interfacial chemistry fail to give a reasonable interpretation. Here, we have identified the time-dependent ion pre-desolvation on the nanopore of hard carbons, which significantly affects the Na⁺ storage efficiency by altering the solvation structure of electrolytes. Consummating the pre-desolvation by extending the aging time, generates a highly aggregated electrolyte configuration inside the nanopore, resulting in negligible reductive decomposition of electrolytes. When applying the above insights, the hard carbon anodes achieve a high average ICE of 98.21% in the absence of any Na supplementation techniques. Therefore, the negative-to-positive capacity ratio can be reduced to 1.02 for full cells, which enables an improved energy density. The insight into hard carbons and related interphases may be extended to other battery systems and support the continued development of battery technology.

由于其具有竞争力的性能，硬碳正在成为支持钠离子（Na-ion）电池商业化的最可行的阳极。然而，硬碳负极的初始库仑效率（ICE）较低，并且模糊的钠离子（Na ⁺）存储机制和界面化学无法给出合理的解释。在这里，我们发现了硬碳纳米孔上随时间变化的离子预去溶剂化，它通过改变电解质的溶剂化结构来显着影响Na ^+的存储效率。通过延长老化时间来完成预去溶剂化，在纳米孔内产生高度聚集的电解质结构，导致电解质的还原分解可以忽略不计。当应用上述见解时，硬碳阳极在没有任何钠补充技术的情况下实现了 98.21% 的高平均 ICE。因此，全电池的负正容量比可降低至1.02，从而提高能量密度。对硬碳和相关界面的深入了解可以扩展到其他电池系统，并支持电池技术的持续发展。