Battery life extension

A method of improving battery power and extending its charge holding capacity has been developed by chemists in Britain.

Kuthanapillil Shaju and Peter Bruce of the University of St Andrews, Scotland, wanted to make new electrode materials that deliver high power (fast discharge) and high energy storage by developing a new way of synthesising a particular lithium intercalation compound (Li(Co1/3 Ni1/3 Mn1/3)O2). As a bonus, they hoped to simplify the complicated manufacturing process.

The team devised a way to mix organic salts of the individual metals - with a solvent in a single step. This is in sharp contrast to the conventional multi-step process used for making the compound.

Using this technique, they made highly uniform lithium oxide intercalation materials in which nickel, cobalt and manganese ions are embedded at regular intervals in the solid, which also contains pores for the electrolyte.

The highly porous nature of the material is crucial to its electrical properties. The pores allow the electrolyte to make intimate contact with the electrode surface, resulting in high rates of discharge and high energy storage.

The team tested the lithium electrode material by incorporating it into a prototype battery and found that it gives the battery far superior power and charge retention.

Increasing the rate by 1000%, so that the battery can be discharged in just six minutes, reduces the discharge capacity by 12%.

The test results suggest that this approach to rechargeable batteries could be used to make even higher power batteries for vehicles and power tools.