Unveiling the microstructural and electrochemical evolution of Si/Sn composite nanofiber anode for lithium-ion batteries

• Applicant: Professor Dr. Francesco Ciucci, since 5/2024
• Subject Area: Synthesis and Properties of Functional Materials
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 533115776

With the overall increase in global population and constant demands for energy supply, the development of sustainable, rechargeable next-generation energy storage systems is highly required. In that regard, lithium-ion batteries (LIBs), which have been currently commercialized, have one significant limitation in the limited specific capacity. To achieve a high energy density, sustainable rechargeable energy storage system, the main approach that has been adopted is to increase the energy density of the battery by replacing the currently used graphite with high capacity anodes such as Si. In order to realize a high performance next-generation energy storage system, the rational design of Si anode should be present to i) maximize active sites for Li storage, ii) allows good ionic/electronic transport, iii) maintain the structural integrity, and iv) stable SEI layer. In this proejct proposal, we aim to explore the Si/Sn composite nanofiber as practical anodes for lithium-ion batteries, which is expected to have the following effects: 1) With the introduction of metallic Sn (9.17 X 106 S), the electrical conductivity is improved compared with Si-only anode (Si is semiconducting) 2) Sn is abundant and environmentally friendly, which can be combined together with Si 3) Sn also acts as an active material, possessing a theoretical capacity of about ~790 mAh g-1 and an average potential of 0.4 V, resembling the high theoretical capacity of Si (~4200 mAh g-1) and average potential of 0.2 V. Considering the high density of Sn (7.3 g cm-3), the difference in the volumetric capacity of Si and Sn is much smaller than that in the gravimetric capacity of Si and Sn: volumetric capacity is more important factor to be looked at if the LIBs are employed for electronic devices or electric vehicles as the battery needs to be prepared in a given volume 4) Incorporation of Sn and Si in one-dimensional nanofiber acts as buffer agents to each other, minimizing the volume changes and structural degradations upon prolonged cycling 5) Nanograins of Sn and Si which help to facilitate Li+ ion transport and porous site between one-dimensional nanostructure that allows for proper electrolyte penetration The overall work packages are presented to address and investigate the merits of Si/Sn composite nanofiber for application in lithium-ion battery anode, and understand the electrochemical and structural evolution of Si/Sn composite nanofiber upon charge and discharge process.

• DFG Programme: Research Grants
• Ehemaliger Antragsteller: Jun Young Cheong, Ph.D., until 4/2024