Paraffin Based Cathode–Electrolyte Interface for Highly Reversible Aqueous Zinc-Ion Battery

In aqueous rechargeable zinc-ion batteries (ARZIBs), aqueous electrolytes tend to initiate structure changes of metal oxides and conductive agents of the electrode, which leads to rapid capacity degradation. In this work, we report an artificial cathode–electrolyte interface (CEI) composed of paraffin that provides a trade-off between Zn2+ intercalation kinetics and stability of the cathode materials. Such paraffin-based CEI can either suppress Mn2+ dissolution and hence stabilize MnO2, or prevent water contact with conductive graphite to maintain its morphology and carbonaceous structure. As a result, the assembled aqueous Zn//MnO2 and Zn//ZnMn2O4 full battery with paraffin-based CEI delivered a superior capacity retention of 82% and 81% after 1000 cycles, 67% and 48% higher than the battery without CEI, respectively. More importantly, both Zn//MnO2 and Zn//ZnMn2O4 full battery also exhibit exceptional cycling stability even at a very high cathode mass loading of 23.6 and 25.2 mg cm–2, respectively, which offers an ideal capacity retention of 73% and 78% after 5000 cycles. Such a unique CEI design on the cathode surface provides a general strategy to improve the cycle life of ARZIBs.