Thermal Voltammetry for cost effective monitoring of battery SOH
Batteries degrade through various mechanisms over time and individual cells in a pack may age differently. This unequal degradation can lead to reduced overall pack performance and lifetime which means particular cells may need to be controlled or replaced accordingly. In order to provide users with a satisfactory information, there is a desire not only to enhance fundamental battery life but also to ensure accurate information is provided in order to manage expectations and optimise battery use. Hence a good diagnosis method capable of monitoring detailed state-of-health (SOH) for individual cells is required. Thermal state of a cell can provide useful information. The reversible heat source contributes to the thermal behaviour of a battery in particular at the initial state of charge (SOC) and discharge. The present technology developed by Imperial Collage London scientists, comprises of a system to monitor the condition of cells of a battery using differential thermal voltammetry (DTV).
In this technology DTV was introduced as a complimentary tool to slow-rate cyclic voltammetry (SRCV) and incremental capacity analysis. The system only requires cell surface temperature and cell voltage measurements. The information is collected by measuring temperature and potential during a constant current discharge. Then DTV parameter is calculated by taking the differential of the temperature divided by the differential of the potential. This is plotted against cell potential, the result gives as much information as a SRCV but with the addition of the thermal data.
Cost effectively monitoring the state-of-health in real time is a real challenge. DTV technology achieves this by reducing operating costs associated with battery overcharging, cutting down maintenance costs arising from premature replacement and lowering operational costs occurring due to sudden battery failure. Existing monitoring methods are limited and not suitable yet as on-board analysis tools, as they require expensive equipment and/or computational capability. The DTV invention addresses the need for an advanced state-of-health monitoring method for lithium-ion batteries to optimise its control strategy and maximise its lifetime with minimal equipment requirement.
Technology Readiness Level
The Technology Readiness Level (TRL) of this technology is 4.
This technology was filed on 24/03/2016. Application no: GB 1605060.1.
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