Developing Thermoregulatory Hydrogel Electrolyte to Overcome Thermal Runaway in Zinc‐Ion Batteries

Abstract

Zinc‐ion batteries (ZIBs) that use water‐based electrolytes have attracted significant attention. However, under harsh conditions, extreme heat is accumulated inside ZIBs, which inevitably causes thermal runway risk. Therefore, the practical applications of rechargeable ZIBs are significantly limited because the internal heat accumulated by harsh conditions induces drastic bulges or even explosions. To overcome this limitation, a self‐adaptive thermoregulatory hydrogel electrolyte (TRHE) that integrates phase transition chains with endothermic effects into agarose backbones via hydrogen bonding interactions is reported. Under extreme conditions, TRHE can tolerate sudden thermal shock; thus, ZIBs can function properly for a period in environments (100 °C) owing to their thermally self‐regulating feature, which alleviates the thermal issues associated with batteries. The hydrogel network with uniform ion migration channels can accelerate ion transport and homogenize ion distribution to realize dendrite inhibition; in addition, other pressing concerns can be effectively resolved, including hydrogen evolution and Zn corrosion, which significantly contribute to the outstanding electrochemical performance. It is believed that the proposed TRHE will help in overcoming thermal runaway in ZIBs and in other aqueous batteries.

Thermally responsive polymers for overcoming thermal runaway in high-safety electrochemical storage devices

“…64,75 In addition to crystallohydrate salts, researchers have explored the adsorption of organic PCMs such as PEG into polymer networks to prepare PCPCs for the thermal management of ESDs. Qian et al 76 proposed a hydrogel electrolyte in which PEG was integrated into agarose main chains via hydrogen bonding for the thermal management of ZIBs. The prepared PCPC exhibited a phase-change temperature of 59.70 1C and a phase-change enthalpy of 143.43 J g À1 (Fig.…”

“…Hydrogels and crosslinked polymers with a three-dimensional (3D) network structure are commonly used as functional polymeric backbones to supporting PCMs. [74][75][76] Novel 3D polymer networks supporting PCMs should be further explored for lithium metal batteries, on which few studies have been reported.…”

“…PCP electrolytes and separators have been utilized in various high-safety ESDs, including batteries, supercapacitors, and fuel cells. 73,74,76 They provide internal thermal management to achieve high security of the device. For the molecular design of PCP electrolytes, there are several factors that should be considered, including the ionic conductivity, phase-change enthalpy, thermal conductivity, and interfacial thermal resistance between the electrolyte and electrode.…”

“…93,95,96 In contrast, the UCST refers to the temperature below which the polymer is insoluble and phase separation occurs. 94,96 Table 1 Various phase-change polymers for avoiding the thermal runaway of electrochemical storage devices 57,66,73,74,76,77,81,85 Phase-change polymers Types Phase-change enthalpy (J g…”

Electrolyte Modulation Strategies for High Performance Zinc Batteries

“…For example, the reported PVA-ZnCl 2 hydrogel, [41] gelatin-PAM hierarchical polymer hydrogel, [42] PAAm/alginate-Zn hydrogel [37] and Zn(CF 3 SO 3 ) 2 -PVDF-HFP [34b] hydrogel electrolytes. They extend the electrochemical stable voltage (~3 V) greatly through decreasing the water solvent ratio and strengthening hydrogen bonding reaction between polymer and water molecules; contribute to the ordered diffusion of Zn 2 + and the uniform deposition of Zn through the Zn 2 + -confinement effect of polymer matrix; and finally improve the cycling stability (up to thousands of cycles) of the battery through suppressing side reactions on electrode and electrolyte sides [39,40] (as shown in Figure 3d, e). Various works where the polymer modification, biopolymers and functional additives addition are reported, which enriches the GPEs family significantly.…”