Triple-function electrolyte regulation towards advanced aqueous Zn-ion batteries

First published: 08 September 2022The poor Zn reversibility has been criticized for limiting applications of aqueous Zn-ion batteries (ZIBs); however, its behaviour in aqueous media is not fully uncovered yet. Here, we address this knowledge gap, indicating that Zn electrodes face a O2 -involved corrosion besides H2 evolution and dendrite growth. Differing from aqueous Li/Na batteries, removing O2 cannot enhance ZIB performance because of the aggravated competing H2 evolution. To address Zn issues, a one-off electrolyte strategy is reported by introducing a triple-function C3 H7 Na2 O6 P, which can take effects during the shelf time of battery. It regulates H+ concentration and reduces free-water activity, inhibiting H2 evolution. A self-healing solid/electrolyte interphase (SEI) can be triggered before battery operation, which suppresses O2 adsorption corrosion and dendritic deposition. Consequently, a high Zn reversibility of 99.6% is achieved under a high discharge depth of 85%. The pouch full-cell with a lean electrolyte displays a record lifespan with capacity retention of 95.5% after 500 cycles. This study not only looks deeply into Zn behaviour in aqueous media but also underscores rules for design of active metal anodes, including Zn and Li metals, during shelf time towards real applications.Junnan Hao, Libei Yuan, Yilong Zhu, Mietek Jaroniec, and Shi-Zhang Qia