A homemade self-healing material utilized as multi-functional binder for long-lifespan lithium–sulfur batteries

Abstract

This study reports a supramolecular self-healing material as a multi-functional binder for lithium–sulfur batteries. The spontaneously damage repair ability of such a binder can be applied to overcome the short cycle-life issue of lithium–sulfur batteries under low current density with deep galvanostatic cycling. Diamines and polybasic acids are used to synthesize the supramolecular self-healing material. 10 wt% amine groups in this designed material provide a large amount of chemical adsorption sites for polysulfides which can effectively inhibit the shuttling of polysulfides and maintain the content of sulfur species in cathode. This N-rich binder is mixed with the sulfur during preparation, which can improve the effective contacting surface of N function groups and sulfur locally. The cells with pure self-healing material binder achieve an initial capacity of 918 mAh g⁻¹, and maintain a reversible capacity of 469 mAh g⁻¹ after 200 cycles at 0.1C, twice higher than the retention capacity of cells with polyvinylidene fluoride binder. After optimization, the cells with a hybrid binder of self-healing material and polyvinylidene fluoride (weight ratio of 1:1) with a sulfur loading of 2.65 mg cm⁻² achieve an initial capacity of 993 mAh g⁻¹, and remain a reversible capacity of 571 mAh g⁻¹ with a capacity fade of 0.2% per cycle after 200 cycles at 0.1C.