Excellent self-healability and cold resistance are attractive properties for a portable/wearable energy-storage device. However, achieving the features is fundamentally dependent on an intrinsically self-healable electrolyte with high ionic conduction at low temperature. Here we report such a hydrogel electrolyte comprising sodium alginate cross-linked by dynamic catechol-borate ester bonding. Since its dynamically cross-linked alginate network can tolerate high-content inorganic salts, the electrolyte possesses excellent healing efficiency/cyclability but also high ionic conduction at both room temperature and low temperature. A supercapacitor with the multifunctional hydrogel electrolyte completely restores its capacitive properties even after breaking/healing for 10 cycles without external stimulus. At a low temperature of -10 °C, the capacitor is even able to maintain at least 80% of its room-temperature capacitance. Our investigations offer a strategy to assemble self-healable and cold-resistant energy storage devices by using a multifunctional hydrogel electrolyte with rationally designed polymeric networks, which has potential application in portable/wearable electronics, intelligent apparel or flexible robot, and so on.

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Poor stability is a long-standing problem preventing the practical application of Li metal anodes, which is fundamentally attributed to their fragile solid electrolyte interphase (SEI) layers that are intrinsically neither adaptable to the dynamic volume change nor self-healable after breakage. Here a Li metal anode is effectively stabilized by in situ integrating its SEI layer into a self-healable polydimethylsiloxane (PDMS) network cross-linked via imine bonding. The self-healing network enables the integrated SEI layer to readily accommodate the volume change but also to repair itself after breaking. Consequently, the resulting anode exhibits excellent cycling stability and a dendrite-free morphology. In a Li/LiFePO4 full cell, this strategy leads to capacity retention up to 99% and a Coulombic efficiency >99.5% after 300 cycles. Our investigation provides a novel self-healing strategy for developing stable Li-metal anodes aiming at high energy-density batteries.

A mussel-inspired strong and stiff polymer exhibits healability, renewability, anti-flammability and solvent-tolerance.