Stabilized and Almost Dendrite-Free Li Metal Anodes by In Situ Construction of a Composite Protective Layer for Li Metal Batteries.

Abstract

Li metal anodes (LMAs) are promising candidates for the anodes of high-energy-density batteries due to their lower reduction potential and high specific capacity. Unfortunately, LMAs usually suffer from uncontrollable Li plating and insecure solid electrolyte interphase layers, especially when used in conjunction with carbonate-based electrolytes. Herein, we proposed using metal alkoxides of titanium butyrate to react with hydroxyl groups on Li metal. A composite protective layer containing TiO2 and ROLi was generated to modify Li (designated as treated Li), leading to dendrite-free LMAs and achieving significantly enhanced cycling stability. Notably, symmetric cells using treated Li electrodes can deliver over 1500 h of stable cycling under a current density of 2 mA cm-2 in an ether-based electrolyte. Moreover, under extreme conditions of 5 mA cm-2 using a carbonate-based electrolyte, symmetric cells employing a treated Li electrode demonstrated stable cycling for over 80 h, as compared to the fluctuating voltage seen after only 10 h of cycling when using a bare Li electrode. Furthermore, full cells using a treated Li anode coupled with a high loading of LiCoO2 cathode (≈15 mg cm-2) displayed excellent cycling stability at 0.2 C over 150 cycles with a high capacity retention of 98.1% and an enhanced average Coulombic efficiency above 99.6%. By comparison, full cells using the bare Li anode drop to 125.4 mA h g-1 with a capacity retention of just 83.3%. The treated Li exhibited superior rate performance and delivered 132.7 mA h g-1 even at 5 C. This strategy provided a facile and effective option for the construction of advanced LMAs.