Lithium metal anodes represent a critical technology to enable next generation rechargeable batteries beyond Li-ion. However, while Li metal anodes represent a high theoretical specific energy (3860 mAh/g), in practice, they are limited by a low Coulombic efficiency (CE), requiring an excess of Li metal in the anode and negating much of the energy density benefit. This low CE stems from several well-known issues associated with lithium metal electrodeposition and dissolution, including electrolyte decomposition, morphological evolution of dendrites and pits, and “dead” Li. In addition, short-circuiting can occur due to the electrically conductive nature of metallic Li, in particular if a dendrite penetrates to the cathode during operation, which leads to significant safety concerns.<br/><br/>Ultimately, all of the challenges associated with Li metal come down to the electrode-electrolyte interface, suggesting that new methods of interfacial engineering are required to rationally design solutions that simultaneously address the chemical, electrochemical, mechanical, and morphological challenges facing Li metal anodes. In this talk, I will demonstrate several examples of interfacial engineering of Li metal anodes, including protective coatings and formation of low-impedance interfaces against solid electrolytes. Moreover, I will discuss the critical roll of <i>in situ/operando</i> analysis of Li metal during cycling to identify the mechanistic origins of the improved performance. I will also present new experimental results on the mechanical properties of Li metal, and their implications on coupled mechanical-electrochemical behavior. This broadly defines the critical field of interdisciplinary research that encompasses “interfacial engineering” of Li metal, and highlights the complementary roll that fundamental and applied research can play to solve one of the most critical challenges facing next-generation rechargeable batteries.

Interfacial engineering of lithium metal anodes: From liquid to solid electrolytes

256th National Meeting (2018)

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