NCM Li-ion battery pack developed by Axeon-led consortium offers 35% improvement in range for same weight as LFP
22 September 2011
|Overview of the project from a 2010 Axeon presentation. Click to enlarge.|
A project led by advanced battery manufacturer Axeon, involving partners Ricardo and Allied Vehicles, and co-funded by the UK Technology Strategy Board has developed a new higher energy-density Li-ion battery pack for use in electric cars that offers a more than a 35% improvement in range compared to a Lithium iron phosphate (LFP) chemistry for the same weight.
The battery uses Nickel Cobalt Manganese (NCM) electrochemistry [Li(NiCoMn)O2], which theoretically requires 50% less volume and 30% less mass when compared to Lithium Iron Phosphate (LFP) chemistry (at the cell level). Axeon, which is Europe’s largest independent Lithium-ion battery systems supplier and works with a variety of Li-ion chemistries, notes that NCM Li-ion batteries are a compromise of electrochemical performance, combined with lower cost.
Electrochemically, the performance is superior to Lithium iron phosphate [LiFePO4] and Lithium cobalt oxide [LiCoO2] in terms of capacity and therefore energy density. In terms of rate capability and therefore power density the electrochemical performance is better than LiCoO2 but not as high as LiFePO4, Axeon says.
|The assembled prototype battery pack. Click to enlarge.|
In 2009, the Technology Strategy Board awarded more than £680,000 (US$1 million) of funding to the consortium led by Axeon—bringing the total project funding to more than £1.3 million (US$2 million)—with the aim of developing an innovative high energy density battery system for an electric vehicle.
A key goal of the project was to confirm that these cell level benefits pass through to the battery pack level when taking into account overall packaging, cell retention, cooling and interconnects, Battery Management System (BMS) components and overall system functionality.
The project included subjecting the battery to automotive environmental validation testing and the learning from this has been incorporated into the final design.
|Pack module. Click to enlarge.|
Axeon and partners Ricardo and Allied Vehicles have now delivered an advanced demonstrator that has been deployed into a test vehicle, increasing its range, functionality and performance. The project has confirmed that it is feasible to replace Lithium Iron Phosphate technology with NCM and that the majority of cell level benefits migrate to battery pack level, the partners said.
The demonstrator pack uses NCM pouch cells that have been packaged in modular building blocks which additionally support a range of thermal management options and additionally allow Axeon to support rapid prototyping into a range of other vehicle types with significantly reduced development lead times.
Added benefits of the new system, which was tested on a vehicle platform from Allied Vehicles, include increased ground clearance, better driver experience due to improved weight distribution and more power, resulting in better drivability.
The new battery also integrates an automotive BMS developed by Ricardo. This works with multiple cell chemistries, has active balancing and delivers diagnostic and prognostic information to the vehicle control system.
The partners are now in active discussions on commercialization of the new technologies.
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