High-Performance Lithium-Ion Negative Electrodes Based on Silicon Nanowires/Graphite Composites

Abstract

Lithium-ion batteries (LIBs) have enabled significant technological progress in recent years and are considered the state-of-the-art technology for electrochemical energy storage.1 As the market for LIBs grows, so do the requirements for improvements concerning their energy and power density, especially with respect to their application in electric vehicles.2 As a consequence, extensive research efforts have been made towards the development of new and optimized materials that could provide the required leap in performance. Of particular interest are alternative anode materials to (partially) replace graphite and, thus, enable faster recharging of the battery cells.3 Non-toxic and abundant understoichiometric silicon oxide and elemental silicon are presently considered the materials of choice in this regard and have been incorporated already in commercial cells.3 In this work, we present the use of a silicon nanowires/graphite composite as active material for the negative electrode. The approach of using such composite is of great interest because it seeks to combine the advantages of the two components – i.e., the excellent cycling stability of graphite and the much higher specific capacity (3579 mAh g-1) and superior rate capability of silicon. The 1D silicon nanowire morphology compared to bulk silicon materials offers short Li+ transport pathways 4 and provides better contact with the graphite particles within the composite. This improved contact ensures first cycle coulombic efficiencies of well above 80% as well as very good cycling stability and high rate capability – even for high areal capacity electrodes – in half-cells and full-cells; the latter comprising NMC-type cathodes. A specific focus was set moreover on the investigation of the impact of (partially) pre-lithiated anodes, providing superior lithium-ion cycling stability with negligible capacity loss over hundreds of cycles. References M. Armand and J. M. Tarascon, "Building better batteries", Nature, 451, 652-657 (2008).D. Bresser et al., “Perspectives of automotive battery R&D in China, Germany, Japan, and the USA", J. Power Sources, 382, 176-178 (2018).J. Asenbauer et al., "The success story of graphite as a lithium-ion anode material – fundamentals, remaining challenges, and recent developments including silicon (oxide) composites", Sustain. Energy Fuels, DOI: 10.1039/D0SE00175A (2020).C. K. Chan et al., “High-performance lithium battery anodes using silicon nanowires", Nat. Nanotechnol., 3, 31–35 (2008).