What next for electric and hybrid vehicle batteries?

What next for electric and hybrid vehicle batteries?
22 July 2014

What next for electric and hybrid vehicle batteries?

Paul Rivera - President Ricardo Inc

There have been several incremental improvements in automotive hybrid and electric vehicle battery technology over the last five years. We have also seen some something of a breakthrough in derivative work in the area of mature lithium ion cathode technology, in particular with Nickel Manganese Cobalt (NMC) materials providing much improved capacity and increased cycle life. Beyond this, there have been some fundamental improvements in pack design. These have focused in particular upon thermal management to optimize capacity, package size, reliability and efficiency, and also in structural integrity which has delivered additional benefits in improved crash worthiness.

But while technology developments have been promising, the big unanswered question remains the issue of cost. As of now, we simply do not see any dramatic cost improvement relative to energy storage becoming available in the near term. This situation is not helped by the wide range of powertrain variants,
from low voltage mild hybrids to high voltage full hybrids and battery electric vehicles, complex packaging challenges and differing requirements in energy density and power density.

The current approach of mass customization unlikely to yield the savings that industry needs; this will only come about through some level of standardization either at the pack level or most probably at the cell level. In addition, there need to be improvements in the supply chain reliability - the supply chain has been erratic in recent years as a result of changes of ownership and strategy.

Notwithstanding these challenges, Ricardo has built up tremendous expertise designing battery packs and battery management systems. We monitor and work with more than 40 different suppliers of battery
cell technology across a broad spectrum of chemistries, formats and applications, and have developed
novel ways to package and thermally manage battery systems that enable us to extract more power and/or capacity whilst protecting cycle life.

While these efforts are commercially attractive in high performance and motorsport applications, the mainstream automotive sector requires a further cost breakthrough in lithium ion technology.

Thus, over the last year, we have seen a push especially from the European and Asian OEMs to look for lower cost hybrid solutions, such as 48 V mild hybrids. This technology requires much smaller energy storage, less than 1kWh, and also opens up the opportunity to form smaller standardized battery packs. The development is also driving targeted research into advanced versions of older battery technologies. For instance, Ricardo is engaged heavily in the research of high-carbon advanced lead acid cells and batteries. The new (compact) cells offer sufficient capacity for mild hybrid applications and are less expensive than Li-ion equivalents. This technology offers a wider temperature range, being able to operate down to – 40 Celsius and up to + 60 Celsius.

The battery industry is still in development and changes are occurring at a rapid pace. Yet it is becoming a key element in many market sectors, not just the automotive space. Today, Ricardo is seeing more and more applications for commercial vehicles, motor cycles and military, agriculture and off-road vehicles as well. This will create new opportunities and challenges for the industry.

This view point featured in RQ Q2 2014 - click here to download the full publication.