Stabilization of Sn Anode through Structural Reconstruction of a Cu–Sn Intermetallic Coating Layer

• Published in: Advanced materials (Weinheim) 2020-10, Vol.32 (42), p.e2003684-n/a
• Main Authors: Wang, Guanzhi, Aubin, Megan, Mehta, Abhishek, Tian, Huajun, Chang, Jinfa, Kushima, Akihiro, Sohn, Yongho, Yang, Yang
• Format: Article
• Language: English
• Subjects: Anodes; Batteries; Copper; Cu–Sn intermetallics; cycling stability; Decay rate; Electrical resistivity; Lithium-ion batteries; mechanical integrity; Plastic deformation; Rechargeable batteries; Reconstruction; Residual stress; Structural design; structural reconstruction; Tin
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.202003684

The metallic tin (Sn) anode is a promising candidate for next‐generation lithium‐ion batteries (LIBs) due to its high theoretical capacity and electrical conductivity. However, Sn suffers from severe mechanical degradation caused by large volume changes during lithiation/delithiation, which leads to a rapid capacity decay for LIBs application. Herein, a Cu–Sn (e.g., Cu3Sn) intermetallic coating layer (ICL) is rationally designed to stabilize Sn through a structural reconstruction mechanism. The low activity of the Cu–Sn ICL against lithiation/delithiation enables the gradual separation of the metallic Cu phase from the Cu–Sn ICL, which provides a regulatable and appropriate distribution of Cu to buffer volume change of Sn anode. Concurrently, the homogeneous distribution of the separated Sn together with Cu promotes uniform lithiation/delithiation, mitigating the internal stress. In addition, the residual rigid Cu–Sn intermetallic shows terrific mechanical integrity that resists the plastic deformation during the lithiation/delithiation. As a result, the Sn anode enhanced by the Cu–Sn ICL shows a significant improvement in cycling stability with a dramatically reduced capacity decay rate of 0.03% per cycle for 1000 cycles. The structural reconstruction mechanism in this work shines a light on new materials and structural design that can stabilize high‐performance and high‐volume‐change electrodes for rechargeable batteries and beyond. A rigid Cu–Sn intermetallic coating layer (ICL) is designed to restrict the volume change of a Sn anode through a structural reconstruction mechanism. A gradual separation of the metallic Cu phase from the Cu–Sn ICL provides a regulated distribution of Cu to buffer the volume change and suppress the mechanical degradation of the Sn anode.