Solid-state batteries, in which the liquid electrolyte used in today’s lithium-ion batteries is replaced by a solid, could offer a leap forward in the performance and safety of batteries. They are regarded by many at the likely next big thing in battery tech. However, there are challenges facing solid-state batteries that require fundamental understanding of the science underpinning their operation. For example, at the negative electrode a Li metal anode is desirable to achieve high energy densities. On discharging such a cell, voids form at the Li/solid electrolyte interface due to limited Li metal creep/diffusion at practical stack pressures and practical discharge currents. These voids accumulate on cycling, leading to detachment of the Li anode and consequently high local currents during charge, triggering growth of dendrites (filaments of Li metal that penetrate the ceramic electrolyte). Li dendrites can penetrate ceramics even with high relative densities. When they reach the cathode (positive electrode) the cell short-circuits and fails catastrophically. The positive electrode also presents interfacial challenges. It is a composite of the active material, e.g. NMC 811, the solid electrolyte and carbon. Volume changes of the active material on cycling, reactivity at the interfaces and the need to ensure effective ion and electron transport throughout the composite are all problems to be addressed.
I shall discuss some of these interfacial challenges as time permits. Combined operando X-ray CT and modelling reveals insights into voiding and dendrites. Dendrite initiation, then propagation across the solid electrolyte are revealed as separate processes, leading to different conclusions as to how they might be mitigated. Crack deflection to mitigate shorts will be considered as will contouring of the interface. There is a lot of interest in interlayers placed between the solid electrolyte and anode current collector. Carbon-based interlayers will be discussed, revealing the structural changes within the interlayer and Li deposition behaviour during the processes of charge and discharge. The performance limits and failure mechanisms of the interlayer will be considered. At the cathode, strategies for accommodating volume changes on cycling involving designer polymers are under investigation and will be presented if I have time.

嘉宾介绍

Peter G. Bruce

Foreign member of the Chinese Academy of Sciences,Member of the Royal Society,Member of the European Academy of Sciences

演讲主题：Solid-state batteries: a challenge of interfaces

Peter Bruce is Wolfson Professor of Materials at the University of Oxford, UK. He co-founded the Faraday Institution, the UK centre for research on electrochemical energy storage, and serves as its Chief Scientist. In 2018 he was appointed as Physical Secretary and Vice President of the Royal Society. In 2023, he was elected as a Foreign Academician of the Chinese Academy of Sciences.
Peter’s research interests embrace materials chemistry and electrochemistry, especially lithium and sodium batteries. Recent efforts have focused on the synthesis and understanding of new anionic redox cathode materials for lithium-ion batteries, the challenges of the lithium-air battery and understanding the processes taking place in solid-state batteries.
Peter’s research has been recognised with a number of prestigious awards and fellowships. He has received the Tilden Prize, the Liversidge Award and the Longstaff Prize from the Royal Society of Chemistry, the Carl Wagner Award of the Electrochemical Society and the Hughes Medal of the Royal Society. He has been named as a Highly Cited Researcher by Thomson Reuters/Clarivate every year since 2015. In the 2022 Birthday Honours List, Peter received a knighthood for his services to science and innovation.