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

摘要

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. 10wt% 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 918mAhg(-1), and maintain a reversible capacity of 469mAhg(-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 2.65mgcm(-2) achieve an initial capacity of 993mAhg(-1), and remain a reversible capacity of 571mAhg(-1) with a capacity fade of 0.2% per cycle after 200 cycles at 0.1C.