Multi-length scale microstructural design of lithium-ion battery electrodes for improved discharge rate performance. Issue 11 (27th September 2021)

• Record Type: Journal Article
• Authors: Lu, Xuekun; Zhang, Xun; Tan, Chun; Heenan, Thomas M. M.; Lagnoni, Marco; O'Regan, Kieran; Daemi, Sohrab; Bertei, Antonio; Jones, Helen G.; Hinds, Gareth; Park, Juyeon; Kendrick, Emma; Brett, Dan J. L.; Shearing, Paul R.
• Is Part Of: Energy & environmental science. Volume 14:Issue 11(2021)
• Page Start: 5929
• Page End: 5946
• Publication Date: 2021-09-27
• Subjects: Energy conversion -- Periodicals; Fuel switching -- Periodicals; Environmental sciences -- Periodicals; Environmental chemistry -- Periodicals; 333.79
• DOI: 10.1039/d1ee01388b
• Languages: English
• ISSNs: 1754-5692

Abstract

Abstract : Microstructural design strategies across multiple length scales for improved rate performance of automotive battery electrodes, assisted by physics-based microstructure-resolved model. Abstract : Fast discharge capability of automotive batteries not only affects the acceleration and climbing performance of electric vehicles, but also the accessible driving range under complex driving cycles. Understanding the intricate physical and chemical processes across multiple length-scales is critical to assist the strategic design of electrodes for improved rate performance. Here, we correlate the discharge rate performance of Ni-rich LiNi1− x − y Co x Mn y O2 (NMC) cathodes to the electrode architectures, ranging from the crystallographic orientations, surface morphology and cracks at single particle level, to the factors that affect the dominance of the solid and liquid-state transport (SST and LST) at electrode level. A random orientation of the primary particles is found to incur an increase of the SST resistance by a factor of 2.35 at 5C and a heterogeneous intra-particle lithiation. Internal cracks significantly restrict the accessibility to the active material. Double-layered particles are proved to be a more promising candidate than single-crystal particles. At electrode level, the SST-dominance depth is quantified for the first time to guide the microstructural tuning and rational operating windows are proposed for electrodes of various architectures. The reaction front is observed to shuttle across the electrode depth to mitigate the polarization, which can provide valuable insights into the battery management development. Finally, by comparing the performance of single crystal and polycrystalline NMC811 electrodes, it is suggested that electrode thickness and porosity are more critical in the former for enhanced discharge rate performance, in contrast to polycrystalline electrodes, in which a gradient particle fraction and size distribution are recommended.