New Production Technique May Lower Li-Ion Battery Costs

A new technique developed at the University of Texas at Austin may prove to be instrumental in lowering the cost of Li-ion battery production. Li-ion batteries are all the rage among hybrid and electric vehicle designers who are looking to cash in on the energy density that the technology offers. The cost of large-format Li-ion batteries makes the technology significantly more expensive than conventional nickel-metal hydride batteries, and compounds the so-called "hybrid premium." A battery pack for the upcoming Chevy Volt will cost nearly $10,000. That added cost has forced EV and PHEV manufacturers into battery-leasing arrangements in order to keep the price of their vehicles affordable to the majority of consumers.

Automakers are working on Li-ion battery development because the technology resolves some of the primary problems with NiMH batteries, namely the energy density of the power pack and the tendency of NiMH formulations to develop a "memory" after a repeated recharges. Li-ion batteries are not without their own drawbacks. Safety issues have plagued the technology, and have produced several spectacular explosion/fire instances in smaller devices. Manufacturers are now working on better membranes and monitoring technologies to prevent the catastrophic over-heating condition that precedes a Li-ion battery failure.

Conventional production methods for Li-ion batteries include a relatively long baking process at temperatures above 700°C that increases production time and costs. The longer baking process results from the use of lithium iron phosphate in automotive batteries. Lithium iron phosphate is less expensive and more stable than the conventional lithium-cobalt oxide formulation, making it more attractive in automotive applications.
UT researchers mixed lithium hydroxide, iron acetate and phosphoric acid in a solvent and put the mixture in the microwave for about five minutes. The team coated the resulting lithium iron phosphate nanoparticles with a conductive polymer and achieved a capacity of 166 mA/h per gram, nearly 98% of the material's theoretical energy storage capacity. The mixture performed well for low-discharge applications. The researchers believe the technique can be modified to produce a material that performs well in high-discharge circumstances, such as is needed for an automobile battery. The technique has the potential to reduce not only the production cost of Li-ion batteries, but also the production time, which has the potential to severely reduce the production volume of hybrid vehicles that use Li-ion batteries.

Source: Technology Review