AllCell Technologies, LLC and the International Copper Association, Ltd., (ICA) have developed a new battery design for hybrid electric vehicles that promises to reduce battery size, weight, and cost while improving fuel economy. The battery design, which takes advantage of the high heat conductivity of copper integrated within AllCell's proprietary passive thermal management system.
The 500 watt-hour lithium-ion battery pack can deliver 22 kilowatts of peak power. AllCell's patented phase change material (PCM) is the key to the improved performance and fuel efficiency. As the battery heats up during discharge, the PCM absorbs large amounts of heat while the graphite/copper matrix quickly conducts heat away from the lithium-ion cells, maintaining the cells within an acceptable temperature range. The result is a thermal management system primarily based on passive materials that require no energy to operate and have no moving parts. The complicated air, liquid, and direct refrigerant cooling systems found in today's hybrid vehicle batteries are replaced with a small fan to provide auxiliary cooling when needed.
Lithium-ion systems are beginning to replace NiMH as the battery of choice for hybrid cars as the energy density, life performance and cost of high power lithium-ion continues to improve. Yet the cost, bulk, and complexity of existing active thermal management systems are holding back industry growth. The addition of PCM to the system acts as a thermal buffer to absorb the peak heat generation and allow it to be dissipated gradually while the addition of a highly conductive graphite/copper matrix allows even more power to be drawn from the battery while maintaining an acceptable battery temperature and temperature gradient.
According to AllCell CEO Said Al-Hallaj, the project builds upon years of research and design work the firm has been leading with a number of large automotive OEMs. "We are very excited about the results of this new design, which addresses the thermal management challenges that have been plaguing battery development in a low-cost, efficient, and effective manner."