Self-protecting aqueous lithium-ion batteries with smart ther-moresponsive separators

TL;DR

This paper introduces a novel aqueous lithium-ion battery with thermoresponsive separators that automatically shut off at high temperatures to prevent hazards and reopen upon cooling, enhancing safety and lifespan.

Contribution

The study develops reversible, thermoresponsive separators for aqueous lithium-ion batteries, enabling automatic self-protection against overheating without performance loss.

Findings

Separator transition temperature is tunable via hydrogel composition.

Selected LiNO3 salt optimizes self-protection and battery performance.

Battery demonstrates effective self-protection at high temperatures.

Abstract

Capacity degradation and destructive hazards are two core challenges for lithium-ion batteries at high temperatures, which need to be solved urgently. Adding flame retardants or fire extinguishing agents can only achieve one-time self-protection in case of emergency overheating. Herein, smart self-protecting aqueous lithium-ion batteries were developed using thermoresponsive separators through in-situ polymerization on the hydrophilic separator. The thermoresponsive separator will close the lithium ions transport channel at high temperatures and reopen when the battery cools down; more importantly, the transition is reversible. We studied the lithium salts influence on the thermoresponsive properties of the hydrogels and selected suitable lithium salt (LiNO3) and concentration (1 M) in the electrolyte to achieve self-protection without sacrificing battery performance. In addition, the shut-off temperature can be tuned by adjusting the hydrophilic and hydrophobic moiety ratio in the hydrogel according to actual demands. This self-protecting lithium-ion battery shows promise for smart energy storage devices with safe and extended lifespan.