Graphene oxide suspension-based electrolyte promotes the cycling performance of aqueous sodium-ion batteries through the interaction between metal ions, free water molecules and functional groups

• Published in: Journal of power sources 2023-01, Vol.555, p.232380, Article 232380
• Main Authors: Bi, Haibo, Luo, Yonghao, Zhao, Chunsong, Ma, Luxiang, Huang, Hui
• Format: Article
• Language: English
• Subjects: Aqueous sodium ion batteries; Free water molecules; Functional groups; Graphene oxide; Metal ions; Prussian blue analogue
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2022.232380

Prussian blue analogue (PBA)-based aqueous batteries are promising solutions for large-scale energy storage. However, PBA cathode materials are still facing erosion and dissolution originating from the strong polarity and high proton activity of water leading to the destruction of their frameworks and poor cycling performance. Herein, we developed a new route to protect Sodium Prussian blue analogue (PB–Na, Na0.65Fe[Fe(CN)6]0.91·□0.09·2.7H2O) by introducing graphene oxide (GO) into the aqueous electrolyte, which can in-situ form an ion selectivity membrane on the separator surface. GO can prevent the diffusion of transition metal ions of dissolved PB-Na penetrating the separator to the anode material by the coordination interaction between transition metal ions and the oxygen-containing functional groups (carboxyl, carbonyl, etc). Meanwhile, hydrophilic groups (hydroxyl, carboxyl, etc) of GO can absorb free water molecules by hydrogen bond and electrostatic interaction reducing the dissolution of PB-Na. Thus PB-Na cathode material-based sodium-ion batteries in the low-concentration aqueous electrolyte can still achieve a capacity of 65.5 mAh g−1 and a high capacity retention of 65.1% after 17000 cycles. This strategy can be considered a simple and effective method to protect active materials in the aqueous batteries. [Display omitted] •Oxygen-containing functional groups in GO hinder the Fe3+ mass transfer.•The nanocapillaries formed in the GO self-assembly membrane can protect PB-Na.•The PB-Na//AC battery with GO additive exhibits superior cycling stability.