A self-healing liquid metal anode for lithium-ion batteries

The gallium-based liquid metal as one of the self-healing materials has gained wide attention, especially in the energy storage system. However, volume expansion with the “liquid–solid-liquid” transformation process still leads to un-controlled electrode failure, which stimulates the irreversibility of liquid metal and hinders their self-healing effect as the anode for lithium-ion batteries. Herein, the polypyrrole (PPy) with highly conductive and adhesive features is first introduced to fasten the liquid metal nanoparticles (gallium-tin alloy, EGaSn) in the integrated electrode and applied as the anode for lithium-ion batteries. A tightly PPy wrapped EGaSn nanoparticles structure is formed during the in-situ polymerization synthesis process, which effectively avoids the detachment of solid alloyed products. Based on the features of PPy, polyacrylic acid is added to facilitate strengthening the integrity of the electrode by constructing the hydrogen bond. The “dual-insurance” design endows the EGaSn to exhibit superior electrochemical kinetics and an astonishing self-healing effect. As a result, the customized anode displays superior cycling stability (499.8 mAh g⁻¹ after 500 cycles at 1.0 A g⁻¹) and rate capability (350 mAh g⁻¹ at 2.0 A g⁻¹). This work enriches the electrode engineering technology of liquid metal nanoparticles and opens up a new way to customize the self-healing anode for lithium-ion batteries.