James Marco, Professor of Systems Modelling and Simulation at WMG, University of Warwick

Significant advances have been made in recent years in our understanding of the electrochemical performance of lithium-ion batteries (LIBs), their degradation, safety, manufacturability and recyclability - in part, through innovations in experimental methods and mathematical modelling.

WMG is at the heart of this technology development through our involvement in fundamental research projects undertaken in collaboration with other leading UK universities, much of which are funded by the Faraday Institution (FI). The FI is the UK’s independent institute for electrochemical energy storage research, skills development, market analysis, and early-stage commercialisation. In parallel, across many different sectors such as automotive, aerospace, rail and energy, WMG is partnering with Original Equipment Manufacturers (OEMs) and system integrators to improve system-scale metrics of cost, energy density, power density and sustainability. This industrial level research is often focussed on improving battery system designs, material selections and manufacturing methods. Notwithstanding these innovations, the individual battery fundamentally remains a passive component. Energy transfer is governed by the requirements of the external load (or supply), often with limited insight as to the impact this will have on battery performance, life and safety. This uncertainty is known to drive sub-optimal solutions or increase downstream costs and development time.

Our vision for Smart Battery technology is to transform the LIB from a passive component into a mechatronic device, through the integration of sensing, communication and controller hardware directly within the battery at the point of manufacture. Figure 1 illustrates a schematic representation of a future Smart Battery to outline the concept, without constraining the final technology choice. For simplicity, a pouch format LIB is used in the illustration, but the concept is format and electrochemistry agnostic. We believe a future Smart Battery will:

• Have the ability to modulate or isolate the electrical current flowing through the terminals.
• Have the ability to measure key internal variables such as electrode potentials, current, temperature, mechanical stress and internal pressure.
• Be able to resolve measurements both spatially and temporally.
• Include localised control and communication hardware to integrate the LIB with its external environment without adding complexity via wireless or powerline data-transfer.

WMG is exploring two primary application pathways for our Smart Battery research: advanced characterisation and direct manufacture:

Advanced Characterisation - We use embedded instrumentation to provide insights into commercial battery performance, degradation and life that is not possible with traditional sensing methods. This is achieved by developing new experimental techniques and novel custom fixtures to embed instrumentation directly inside commercially available LIBs. For example, we are working on battery safety by monitoring the increase in cell internal temperature and pressure accumulation. In addition, for larger format cells, we have measured spatial variations in temperature and mechanical strain that occur during different levels of electrical and thermal loading. Key to this work is the ability to integrate sensors into the battery structure in a method that does not negatively impact its performance (e.g., energy capacity and impedance) and its life.

Direct Manufacture - We are leveraging our capability to build LIB technology, within our Battery Scale-Up Line (BSU), to explore the process challenges of directly manufacturing Smart Batteries for use in high-value systems or niche applications.

Impact - The potential impact of our Smart Battery research across the complete value chain is significant. Within the context of battery manufacturing, the ability to measure internal states of temperature and pressure may underpin optimised formation processes – improving productivity and reducing the energy demands associated with volume manufacture. At the system scale, we are undertaking research to optimise the integration of Smart Batteries into the complete battery pack to further increase performance, safety and end-of-life management. This research has the potential to drive new physics-informed models of the battery and new approaches to state-of-X (SoX) estimation for the next-generation of battery system management (BMS) designs. The ability to monitor “in-cell” behaviour within a battery pack and manage the distribution of electrical current within individual cells can fundamentally change our approach to battery systems engineering.