Carbonized Polymer Dots-Induced Multivalent Hydrogen-Bonding Networks in Hydrogel Electrolytes for High-Performance Low-Temperature Zinc-Ion Batteries

Abstract

Aqueous zinc-ion batteries (AZIBs) are considered promising candidates for next-generation energy storage systems owing to their intrinsic safety, low cost, high theoretical capacity (820 mAh g-1), and environmental friendliness. However, the excessive free water in conventional aqueous electrolytes severely compromises low-temperature performance due to the inherently high freezing point of water. Moreover, water-induced parasitic reactions on the Zn metal anode, including hydrogen evolution, corrosion, and passivation, inevitably lead to poor electrode reversibility and limited cycling stability, thereby hindering their practical applications in low-temperature environments. Herein, carbonized polymer dots (CPDs) with abundant surface functional groups are introduced to regulate the hydrogen-bonding environment within the hydrogel electrolyte. The CPDs effectively disrupt the original hydrogen-bonding network of free water and reconstruct multivalent hydrogen-bonding interactions among CPDs, free water, and polyacrylamide (PAM) chains. Such a strategy immobilizes free water and converts it into bound water, thereby significantly depressing the freezing point of the electrolyte. In addition, CPDs facilitate rapid Zn2+ transport under low-temperature conditions while simultaneously suppressing Zn dendrite growth and undesirable side reactions. Furthermore, the influence of CPDs content on the electrochemical performance was systematically investigated by tuning the volume ratio between CPDs and PAM. When the CPDs volume ratio reached 0.3, the Zn||Zn symmetric cell exhibited highly stable cycling performance for 800 h (2 mA cm-2, 1 mAh cm-2) at -25℃. This work provides a feasible strategy for the rational design of high-performance low-temperature resistance hydrogel electrolytes for advanced zinc-ion batteries.