Long life-cycle lithium metal batteries employing self-healing silica-based nanocomposite solid electrolytes.

The inherent limitations linked to the chemistry of Li-ion batteries and the growing demand for devices with high energy density have recently brought renewed interest in the exploitation of lithium metal anode for next-generation secondary batteries. Unfortunately, uncontrolled growth of Li dendrites on the anodic surface is preventing its practical implementation [1]. This can be overcome using mechanically strong solid electrolytes, such as nanocomposite polymeric ones that hinder dendrite growth thanks to the homogenous dispersion of strengthening ceramic fillers into a soft polymeric matrix, otherwise prone to dendrite piercing [2]. Following an approach similar to the one previously exploited for the incorporation of TiO2 nanoparticles into polymeric matrices [3], relatively high content (20-30 wt%) of PEO-grafted silica nanoparticles have been successfully encompassed into high-Mw PEO to produce ceramic-in-polymer solid electrolytes that display an ionic conductivity comparable to polymeric analogues and a highly improved stability upon cycling. Moreover, these electrolytes present a notable self-healing behaviour, often regarded as an important feature for next-generation batteries [4]: thanks to the well-known SiO2 reaction with Li [5], the dendrites grown into the separator are disrupted and several cells autonomously restarted their operation after failure. [1] D. Lin, Y. Liu, Y. Cui, Nature Nanotechnology; 12 (2017); 194. [2] J. Wan, J. Xie, D. G. Mackanic, W. Burke, Z. Bao, Y. Cui; Materials Today Nano; 4 (2018), 1-16. [3] F. Colombo, S. Bonizzoni, C. Ferrara, R. Simonutti, M. Mauri, M. Falco, C: Gerbaldi, P. Mustarelli, R. Ruffo; Journal of The Electrochemical Society; 167 (2020); 070535. [4] L. Mezzomo, C. Ferrara, G. Brugnetti, D: Callegari, E: Quartarone, P. Mustarelli, R. Ruffo; Advanced Energy Materials; 10 (2020), 2002815. [5] K. Liu, D. Zhuo, H. W. Lee, W. Liu, D. Lin, Y. Lu, Y. Cui; Advanced Materials; 29 (2017); 1603987.