Introducing a novel battery design for high-performance hybrid vehicles
First introduced into the market because of environmental and fossil fuel dependency concerns, hybrid vehicles show promise as a sustainable mode of transport that can increase fuel economy and reduce emissions. To fulfil this promise, vehicle companies around the globe are working on different ways to advance this comparatively young technology. One of these advances has come from global vehicle development services provider FEV Europe that has introduced a new high-performance battery system for hybrid vehicles using a cell-to-module approach. Developed, built and tested as part of the EU-funded ADVICE project, the battery system offers optimal support for power hybrids. It has a high-power density of 2 kW/kg, enabling 100 kW of power with just 2 kWh of energy and a weight of only 50 kg. FEV demonstrated and validated the system’s feasibility in collaboration with Volvo Cars, the coordinator of the ADVICE project. The battery concept is based on a central, function-integrating T-bone element for the battery’s mechanical structure. It includes integrated cooling, providing a cost-, weight- and package-optimised modular design. “This significantly reduces the number of components and assembly steps,” explains FEV Group CEO Prof. Stefan Pischinger in a news release posted on the ‘Automotive World’ website. “The extrusion process selected for the function-integrating T-bone structural element ensures a high degree of flexibility, providing further positive scaling effects for successful cost reduction. In addition, the compact design allows stacking of multiple modules.”
The system in detail
A thermally conductive adhesive is used to attach the battery cells to both sides of the T-bone structure, and a powder coating is applied to electrically insulate the cells to the T-bone carrier. Attention is paid to the layer thickness of both the powder coating and the thermally conductive adhesive. Both are applied in a way that ensures minimal thermal contact resistance between the coolant and the battery cells. A self-adhesive compression foam applied between battery cells compensates for any tolerances of the cells over the length of the T-bone structural element, and it also electrically insulates the battery cell housings from each other. Cell packs are mechanically fixed to the T-bone carrier by pressing them to a unit length by means of two end plates and then applying screws through the end plates. In this battery concept, sensor cabling and slave units are installed centrally between the cell contacts while the air flow for additional cooling of the cells is guided through the module cover. The air ducts run parallel to the centrally installed slave units via strips of conductive metal called busbars. The module cover therefore also helps to further reduce both the number of individual components and the weight of the modules. The air flowing through the cooling channels inside the T-bone keeps the battery cells cool from the side and from the bottom. As stated in the news release, “[t]he functional integration of the cooling system into the structural component optimizes the space requirement and weight of the battery. In addition, the innovative busbar cooling system enables maximum power densities through targeted management of cell temperatures at the ‘hotspots’.” ADVICE (ADvancing user acceptance of general purpose hybridized Vehicles by Improved Cost and Efficiency) aimed to increase the percentage of hybrid vehicles on the market through technologies that reduce emissions and increase electric driving range. The project ended in September 2020. For more information, please see: ADVICE project web page
Keywords
ADVICE, hybrid vehicle, battery, battery cell, module, cooling, T-bone
