Supercapacitors

Lead researchers: Dr Ganesh Madabattula

PI’s: Dr Billy Wu, Dr Monica Marinescu and Dr Gregory Offer

Funding: 

• Innovate UK, Advanced Lithium-Ion Capacitors and Electrodes (ALICE)-102655

The project aims to develop advanced lithium-ion capacitors based on lithium titanium oxide (LTO) and activated carbon as electrode materials to provide optimum energy density and power density with long cycle life for energy storage applications. Imperial provided physics-based modelling insights to the collaborators in the project to develop optimised cells. In this project, rate capability, the role of capacity ratio of electrodes, and pre-lithiation of LTO on cell performance and capacity fade were studied. The diagnostic techniques for capacity fade in the capacitors were developed. Newman’s porous electrode theory-based P2D models were simulated in COMSOL Multiphysics for the analysis.

Collaborators:

• Johnson Matthey
• Cummins Inc
• University of Oxford
• WMG-Warwick University
• Delta Motorsport Ltd

Publications:

1. Madabattula G, Wu B, Marinescu M, Offer G, 2020, Degradation diagnostics for Li4Ti5O12-based lithium-ion capacitors: Insights from a physics-based model, Journal of the Electrochemical Society, Vol: 167(4), Page: 043503.
2. Madabattula G, Wu B, Marinescu M, Offer G, 2019, How to design lithium-ion capacitors: modelling, mass ratio of electrodes and pre-lithiation, Journal of The Electrochemical Society, Vol: 167, Page: 013527.
3. Madabattula G, Wu B, Marinescu M, Offer G, 2019, 1D Electrochemical Model for Lithium Ion Capacitors in Comsol.

Lead researchers: Dr Tribeni Roy and Dr Mohammad Amin Samieian

PI’s: Dr Huizhi Wang, Dr Yatish Patel, Dr Monica Marinescu and Dr Gregory Offer

Funding: 

• InnovateUK WIZer Batteries, collaborative R&D with Williams Advanced Engineering, CodePlay Software Ltd., ZapGO Ltd. & Silver Power Systems Ltd.

‌‌‌Research into supercapacitors has recently gained prominence owing to the development of high potential window electrolytes (ionic liquids/non-aqueous electrolytes) and a range of electrode materials with controlled porosity. Supercapacitors are viewed as an add-on to lithium-ion batteries in electric vehicles to enhance the overall power density, enable fast charging and longer cycle life. 

However, the behaviour of the recently developed electrolytes for enhancing energy density via formation of (crowded) double layer is not fully understood. Also, the random pore size distribution on the electrode is a limiting factor owing to reduced capacitance despite using high potential electrolytes.

We are developing multiscale models (coupled DFT-MD-FEA) to understand the behaviour of these electrolytes in terms of double-layer formation, diffusion in the electrode pores and thereby predict the optimal pore size distribution on the electrode to enhance the energy density while maintaining reasonably high-power density.

Experimental facilities include Electrochemical Impedance Spectroscopy (EIS), Cyclic Voltammetry (CV), Power cycling, Degradation tests, and Cell expansion measurement tests.

Collaborators:

• ESE group - Department of Mechanical Engineering: Dr Ruben James Tomlin, Dr Abir Ghosh and Dr Ganesh Madabattula

Publications:

1. Jamieson L, Roy T, Wang H, 2020, Postulation of optimal charging protocols for minimal charge redistribution in supercapacitors based on the modelling of solid phase charge density, Journal of Energy Storage.

Presentations:

1. Invited talk of Dr Tribeni Roy on the topic Multi-scale Modelling of High Energy Density Supercapacitors in Institute for Molecular Science and Engineering (IMSE) Webinar series on Molecular Engineering for Next Generation Batteries, November 2020.

Awards:

• Mechanical Engineering Departmental Prize - Unwin Postgraduate Prize 2020 to MSc student Luke Jamieson, supervised by Dr Tribeni Roy and Dr Huizhi Wang, November 2020.