Influence of Cu contents on the interfacial properties of Sn anode materials: an ab-initio studyThis project aims to use first-principles calculations to study the influence of impurities on the interfacial mechanical properties of Sn anode materials during the charging-discharging process. Tin, a promising candidate anode material for Li-ion batteries (LIBs), has been widely investigated due to its high theoretical capacity of 994 mAh g−1, which is about two and a half times of conventional graphite anode. However, its application in LIBs has been hampered by the substantial volume change (~300%) during lithiation (charging) and de-lithiation (discharging) processes, which causes fracture and pulverization of active electrode particles and loss of electrical contact between active materials and copper (Cu) current collector or other conductive phases. This directly results in an early capacity loss and poor cyclability. To alleviate deleterious effects of volume change and loss of electrical contact with Cu current collector, a variety of structures have been investigated in experiments. Recent theoretical and experimental studies showed that particle pulverization cannot be avoided in Sn-based electrodes, and even using nano-sized crystals (~10 nm), delamination can still happen between active materials and conductive phases, inducing rapid capacity decay. Previously, we studied the evolution of interfacial mechanical properties of electrode-collector interface during lithiation. Here, by using first-principles calculations, we further investigate the effects of impurities on the interfacial properties of electrode-collector. The findings from this work will contribute to a better understanding of interfacial properties of Sn-based anodes and help to optimize the interface properties during electrochemical cycling
Principal investigatorChunsheng Lu email@example.com
Area of scienceEnergy Materials, Energy Minerals
Over recent years, numerous efforts have been devoted to improving the electrochemical performance of Sn anode materials. Although optimized Sn anodes demonstrate higher specific capacities and longer cyclability, cracks and pulverization of electrode materials have not been solved and their current electrochemical performance cannot meet commercial requirements. By studying the effect of impurities, we aim to strengthen the interfacial strength between active materials and Cu current collector, which is vital to enhance the durability of Sn anodes. Considering experimental difficulties, this project is designed to complement this important part via an atomistic perspective
By using first-principles calculations, we first studied the influence of Cu content on the interfacial mechanical properties of Sn anode materials. First, we studied the influence of CuxSn alloys on the interface strength of electrode-collector, and then we simulated their fracture strength. It is shown that the formation of CuxSn alloys between Sn active materials and Cu current collectors can enhance the interface strength and deformation resistance at large strains.
Furthermore, we studied the influence of Co doping on the interfacial properties of Sn anode materials. By doping Co in different interfacial positions, we investigated the influence of Co on the interface strengths of electrode-collector. In addition, the influence of Co doping on the thermodynamic stability, electronic structures and interfacial bonding was also explored. We found out that Co doping displays an obvious enhancement effect, which increases the interfacial strength by ~10%.
It is usually time-consuming for simulations of interfacial structures, and Pawsey Centre’s resources ensure the solution. Here, we would like to take this opportunity to thank Pawsey Centre’s administrators (e.g., Daniel Grimwood, Ashley Chew, Mark O’Shea et al.) for their kind and timely help and support
List of Publications
Panpan Zhang, Zengsheng Ma, Yan Wang, Youlan Zou, Lizhong Sun, Chunsheng Lu, Lithiation-induced interfacial failure of electrode-collector: a first-principles study, Materials Chemistry and Physics 222 (2019), 193–199.
Figure 1. The stress-strain curve of a Li2CuSn/Cu interface and the fully relaxed interface structures at various stages of strain
Figure 2. Relaxed LiSn/Cu interfaces with Co doping in (a) interfacial sites, (b) interfacial Sn1, (c) interfacial Li1 and (d) interfacial Cu1 sites, respectively, with illustrated main Sn–Co and Cu–Co bonds and their bond lengths on interfaces.