Low-temperature and high-rate Zn metal batteries enabled by mitigating Zn²⁺ concentration polarization

Despite of the thriving development of rechargeable batteries, the realization of high-rate batteries at low temperature remains challenging. Herein, low-temperature and high-rate Zn metal batteries (ZMBs) are successfully developed by regulating electrolyte chemistry. Zn²⁺ concentration polarization is first revealed to be the kinetic restriction of nonaqueous high-rate ZMBs at low temperature. Furthermore, by using an acetonitrile/water co-solvent electrolyte, the Zn²⁺ solvation structure is modulated with effectively promoted ion pairs dissociation and decreased size of Zn²⁺ solvation shell, thus greatly promoting Zn²⁺ transport and mitigating Zn²⁺ concentration polarization. Consequently, stable cycling for over 500 h of Zn-Zn symmetric batteries at 5 mA cm⁻² under − 40 °C or at 10 mA cm⁻² under −20 °C is achieved. This superior kinetics and high cumulative cycling capacity reach a record level among the reported low-temperature ZMBs. Moreover, the high-rate V₂O₅-Zn full batteries under −40 °C also exhibit great prospect of practical application.