Towards high-performance flexible aqueous zinc hybrid batteries via low-concentration electrolyte strategy

Aqueous zinc hybrid batteries (AZHBs) are highly promising energy storage devices for flexible electronic applications due to their inherent safety and low cost. However, conventional aqueous electrolytes used in AZHBs exhibit rapid performance degradation at low temperatures and narrow electrochemical stability window (ESW), which hinders the practical application of AZHBs. Additionally, traditional design strategies for aqueous electrolytes struggle to address simultaneously the challenges of poor low temperature, limited ESW, high cost, and safety concerns. Herein, we report a low-concentration Zn(ClO₄)₂/LiClO₄ hybrid aqueous electrolyte with excellent low-temperature performance and a wide ESW, due to the disruption of the hydrogen-bond network and the inhibition of water activity in the electrolyte. The Zn//LiMn₂O₄ battery using the optimized electrolyte displays a high working voltage window (1.0 V - 2.2 V), excellent low-temperature performance (91.7 % capacity retention at −20 °C relative to room temperature), and superior rate capability (67 % capacity retention from 0.5 C to 20 C), outperforming most reported AZHBs. Moreover, a polyacrylamide-based hydrogel electrolyte is subsequently applied to fabricate a flexible quasi-solid-state battery, which demonstrates excellent low-temperature performance, outstanding flexibility, and high reliability. This work proposes a promising strategy using a low-concentration electrolyte for high-performance aqueous energy storage device tailored for wearable electronics.