Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology, Department of Chemical Engineering, Tsinghua University , Beijing 100084, China.
J Am Chem Soc. 2017 Jun 28;139(25):8458-8466. doi: 10.1021/jacs.6b12358. Epub 2017 Mar 28.
Self-healing capability helps biological systems to maintain their survivability and extend their lifespan. Similarly, self-healing is also beneficial to next-generation secondary batteries because high-capacity electrode materials, especially the cathodes such as oxygen or sulfur, suffer from shortened cycle lives resulting from irreversible and unstable phase transfer. Herein, by mimicking a biological self-healing process, fibrinolysis, we introduced an extrinsic healing agent, polysulfide, to enable the stable operation of sulfur microparticle (SMiP) cathodes. An optimized capacity (∼3.7 mAh cm) with almost no decay after 2000 cycles at a high sulfur loading of 5.6 mg cm was attained. The inert SMiP is activated by the solubilization effect of polysulfides whereas the unstable phase transfer is mediated by mitigated spatial heterogeneity of polysulfides, which induces uniform nucleation and growth of solid compounds. The comprehensive understanding of the healing process, as well as of the spatial heterogeneity, could further guide the design of novel healing agents (e.g., lithium iodine) toward high-performance rechargeable batteries.
自愈合能力有助于生物系统维持其生存能力并延长其寿命。同样，自愈合对于下一代二次电池也很有好处，因为大容量电极材料，特别是氧或硫等阴极，由于不可逆和不稳定的相转移而导致循环寿命缩短。在这里，通过模拟生物自愈合过程——纤维蛋白溶解，我们引入了一种外部分子愈合剂——多硫化物，以使硫微粒（SMiP）阴极能够稳定运行。在高硫负载量为 5.6mg/cm 的情况下，优化后的容量（约 3.7mAh/cm）在 2000 次循环后几乎没有衰减。不活泼的 SMiP 被多硫化物的溶解作用激活，而不稳定的相转移则通过多硫化物空间异质性的缓解来介导，这诱导了固体化合物的均匀成核和生长。对愈合过程以及空间异质性的全面理解，可以进一步指导新型愈合剂（例如碘化锂）的设计，以实现高性能可充电电池。
