WHole-Battery - Thermally optimized high-performance battery
The current lithium ion battery technology used in the automotive sector is based on metal oxide (NMC) and graphite electrodes, which offer high energy and power densities. This combination of materials delivers high electrochemical performance, but thermally it is quite vulnerable; high temperatures lead not only to accelerated ageing, but various mechanisms may lead to cell failure, and even to spontaneous combustion (“thermal runaway”). For this reason the cells need to be kept at their optimal temperature, that is between 20 and 40°C, at all times. Composite materials can avoid thermal resistance and thermal buffers can smooth out temperature peaks.
WHole-Battery combines both strategies. A highly heat conductive graphite matrix is combined with a phase change material (PCM) to make a phase change compound material (PCCM). This enables quick heat removal and quick heat distribution within the PCM, resulting in cell temparature smoothing. In this process the PCM temporarily absorbs all excess heat, due to its high enthalpy of fusion. Through the connection of the graphite matrix with the casing’s aluminium and integrated cooling channels produced with additive manufacturing, a compact, light, highly efficient cooling concept is realized for traction batteries that enables highest performance and current levels. Spikes in temperature through fast charging or high loads during driving are prevented. In the mid-term, this makes much higher charging currents possible, and consequently much shorter charging times for electric vehicles.
In WHole-Battery, methods are developed and the concept is tested on several battery modules.
The following questions are to be answered:
• Will the WHole-Battery concept enable charging a car battery to 80% of its capacity in under 10 minutes?
• Can the PCCM’s heat conductivity be raised to 10-25 W/(m K) in actual practice?
• Would that enable building a battery module that is 15% more compact?
• Would that enable a weight reduction of 20% in the battery module?
• Can the needed cooling power be reduced by half in this way?
• Can the LIB be connected to the PCCM, and the PCCM to the casing, with a Graphite matrix?
• Is it possible to both integrate the cooling channels directly and to provide for a material gradation within the casing through WAAM technology?
Project start: April 2019
Project duration: 24 months
AIT Austrian Institute of Technology GmbH (Coordinator)
AVL LIST GmbH
LKR Leichtmetallkompetenzzentrum Ranshofen GmbH
Schunk Carbon Technology GmbH (Projektpartner), Stohl Group GesmbH
Funding tool: Mobilität der Zukunft