Ma Le Anh, Naylor Andrew J, Nyholm Leif, Younesi Reza
Department of Chemistry-Ångström Laboratory, Uppsala University, 75121, Uppsala, Sweden.
Angew Chem Int Ed Engl. 2021 Feb 23;60(9):4855-4863. doi: 10.1002/anie.202013803. Epub 2021 Jan 8.
The interfacial reactions in sodium-ion batteries (SIBs) are not well understood yet. The formation of a stable solid electrolyte interphase (SEI) in SIBs is still challenging due to the higher solubility of the SEI components compared to lithium analogues. This study therefore aims to shed light on the dissolution of SEI influenced by the electrolyte chemistry. By conducting electrochemical tests with extended open circuit pauses, and using surface spectroscopy, we determine the extent of self-discharge due to SEI dissolution. Instead of using a conventional separator, β-alumina was used as sodium-conductive membrane to avoid crosstalk between the working and sodium-metal counter electrode. The relative capacity loss after a pause of 50 hours in the tested electrolyte systems ranges up to 30 %. The solubility of typical inorganic SEI species like NaF and Na CO was determined. The electrolytes were then saturated by those SEI species in order to oppose ageing due to the dissolution of the SEI.
钠离子电池（SIBs）中的界面反应尚未得到充分理解。由于与锂类似物相比，SEI 成分的溶解度更高，在 SIBs 中形成稳定的固体电解质界面（SEI）仍然具有挑战性。因此，本研究旨在阐明受电解质化学影响的 SEI 溶解情况。通过进行具有延长开路暂停时间的电化学测试，并使用表面光谱学，我们确定了由于 SEI 溶解导致的自放电程度。代替使用传统的隔膜，β-氧化铝被用作钠导电膜，以避免工作电极和钠金属对电极之间的串扰。在测试的电解质系统中，暂停 50 小时后的相对容量损失高达 30%。测定了典型无机 SEI 物种如 NaF 和 Na₂CO₃ 的溶解度。然后使电解质被这些 SEI 物种饱和，以对抗由于 SEI 溶解而导致的老化。
