Toward High Temperature Sodium Metal Batteries via Regulating the Electrolyte/Electrode Interfacial Chemistries
Xueying Zheng, Zhang Cao, Zhen‐Yi Gu, Liqiang Huang, Zhonghui Sun, Tong Zhao, Sijie Yu, Xing‐Long Wu, Wei Luo, Yunhui Huang
Abstract
Rechargeable batteries based on sodium metal anodes (SMAs) are endowed with much higher energy density than traditional sodium-ion batteries. However, the use of SMAs brings intrinsic challenges of dendrite growth and unstable solid/electrolyte interphase (SEI) formation. This situation can be further exacerbated at high temperature (>55 °C, HT). Here, we resolve such “HT-challenge” by formulating a thermally stable sulfolane (SL)-based electrolyte that regulates the electrode/electrolyte interfacial chemistries. Besides rapid Na anode passivation enabled by fluoroethylene carbonate (FEC) molecules, a nitrile-based 1,3,6-hexanetricarbonitrile (HTCN) cosolvent is simultaneously introduced, whose three electron-rich -C≡ N groups interact with the electropositive metal ions of Na3V2(PO4)2O2F, shielding away solvent attacks occurring at the cathode interface. As a result, we realize a high capacity retention (91.7% after 500 cycles at 1 C) for the Na/Na3V2(PO4)2O2F cell at 60 °C, with a high average carbon equivalent (CE) of ∼99.6%. Even at 80 °C, the cell still delivers ∼89.1% of its initial capacity after 100 cycles, whereas the control sample fails rapidly within 30 cycles.