A True Non-Newtonian Electrolyte for Rechargeable Hybrid Aqueous Battery

Abstract

The rechargeable aqueous hybrid battery is a unique system in which the Li-ion mechanism dominates the cathode while the first-order metal reaction of stripping/depositing regulates the anode. This battery inherits the advantages of the low-cost anode while possessing the capability of the Li-ion cathode. One of the major challenges is to design a proper electrolyte to nourish such strengths and alleviate the downsides, because two different mechanisms are functioning separately at the node–electrolyte and the cathode–electrolyte interfaces. In this work, we design a non-Newtonian electrolyte which offers many advantages for a Zn/LiMn2O4 battery. The corrosion is kept low while almost non-dendritic zinc deposition is confirmed by chronoamperometry and ex situ microscopy. The gel strength and gelling duration of such non-Newtonian electrolytes can be controlled. The ionic conductivity of such gels can reach 60 mS⋅cm−1. The battery exhibits reduced self-discharge, 6–10% higher specific discharge capacity than the aqueous reference battery, high rate capability, nearly 80% capacity retention after 1000 cycles, and about 100 mAh⋅g−1 of specific discharge capacity at cycle No. 1000th. Negligible amorphization on the cathode surface and no passivation on the anode surface are observed after 1000 cycles, evidenced by X-ray diffraction and scanning electron microscopy on the post-run battery electrodes.