High-efficiency, anode-free lithium-metal batteries with a close-packed homogeneous lithium morphology

• Published in: Energy & environmental science 2022-02, Vol.15 (2), p.843-854
• Main Authors: Su, Laisuo, Charalambous, Harry, Cui, Zehao, Manthiram, Arumugam
• Format: Article
• Language: English
• Subjects: Anodes; Batteries; Copper; Crystal structure; Crystallinity; Efficiency; Electrochemical analysis; Electrochemistry; Electrodes; Electrolytes; Electrolytic cells; Energy storage; Heterogeneity; Lithium; Morphology; Performance enhancement; Plating; Storage batteries; Synchrotrons
• ISSN: 1754-5692; 1754-5706
• DOI: 10.1039/d1ee03103a

Anode-free lithium-metal batteries (LMBs) are ideal candidates for high-capacity energy storage as they eliminate the need for a conventional graphite electrode or excess lithium-metal anode. Current anode-free LMBs suffer from low Coulombic efficiency (CE) due to poor lithium stripping efficiency. Advanced electrolyte development is a promising route to maximize lithium plating and stripping CE and minimize capacity fade. However, a poor understanding of the mechanisms by which advanced electrolytes improve performance hampers progress in the practical development of anode-free LMBs. Here, we use synchrotron techniques and other tools to analyze the influence of three commercially available electrolytes on the composition, heterogeneity, kinetics, morphology, and electrochemistry of anode-free LMBs. Advanced electrolytes improve the electrochemical performance of anode-free LMBs by forming much denser and better-packed Li morphologies on a Cu current collector than on the conventional electrolyte. Li plates uniformly over the electrode area with the advanced electrolytes rather than in a few active sites. Inactive crystalline Li with heterogeneous distribution dominates the capacity degradation of anode-free cells, especially with the conventional electrolyte, indicating that reducing the amount of "dead" crystalline Li will significantly improve the cycling stability of anode-free cells. The understanding of the Li plating and stripping process obtained from this work will accelerate the development of anode-free LMBs with high efficiency. Advanced electrolytes enable highly efficient anode-free lithium-metal batteries by forming dense, close-packed Li morphology on the Cu anode current collector, which is related to the crystallinity of Li at the beginning of plating.