Micro-scale graded electrodes for improved dynamic and cycling performance of Li-ion batteries

Journal article

Li-ion battery cathodes based on LiFePO4 are fabricated by a layer-by-layer spray printing method with a continuous through thickness gradient of active material, conductive carbon, and binder. Compared with cathodes with the more usual homogeneous distribution, but with the same average composition, both C-rate and capacity degradation performance of the graded electrodes are significantly improved. For example at 2C, graded cathodes with an optimized material distribution have 15% and 31% higher discharge capacities than sprayed uniform or conventional slurry cast uniform cathodes, and capacity degradation rates are 40–50% slower than uniform cathodes at 2C. The improved performance of graded electrodes is shown to derive from a lower charge transfer resistance and reduced polarization at high C-rates, which suggests a more spatially homogeneous distribution of over-potential that leads to a thinner solid electrolyte interphase formation during cycling and sustains improved C-rate and long-term cycling performance.

Authors: Cheng, C; Drummond, R; Duncan, S; Grant, P

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Elsevier
• Journal: Journal of Power Sources
• Volume: 413
• Pages: 59-67
• Publication date: 2018-12-15
• Acceptance date: 2018-12-09
• DOI: 10.1016/j.jpowsour.2018.12.021
• ISSN: 0378-7753
• Keywords: electrode engineering; solid electrolyte interphase; graded electrode; layer-by-layer spray printing; Li-ion battery; electrochemical impedance spectroscopy