Hitachi Maxell, Ltd. announced that it will start shipping prismatic lithium ion rechargeable batteries using a new special silicon negative electrode in June 2010.
Maxell has developed the new negative electrode using a new nano silicon composite material, in which nano-sized silicon particles are dispersed within an ion conductive material. This has allowed a significant improvement in battery capacity and provides enhanced performance at high duty ratios, Maxell claims.
Initially Maxell will utilize this new technology in lithium ion rechargeable batteries for smartphones. The new silicon negative electrode is compatible with current Maxell lithium ion rechargeable batteries in terms of charging voltage and operating voltage. Thus longer operating duration and more rapid charging can now be realized without the need for hardware based changes.
In general the fundamental performance of lithium ion rechargeable batteries is determined largely by the type of materials used for positive and negative electrodes. Today, graphite materials are generally used for the negative electrode, but this material has almost reached its theoretical limit of capacity, so there exists a growing need to develop new material to obtain higher capacities.
Amongst Maxell?s various technologies is the ability to insert and extract a large number of lithium ions while charging and discharging lithium ion rechargeable batteries. To complement this, Maxell has engaged in ongoing research and development into the usage of several alternative materials in abundant supply including silicon.
Despite its lack of scarcity silicon material has always exhibited a unique disadvantage. Its volume changes drastically when charge and discharge are repeated, and it causes a collapse of particle structure of the material and a decline in the cycle life of the batteries in
which it is used. Because of this silicon material has not been successfully utilized for practical use in lithium ion rechargeable batteries before now. The batteries using this new negative electrode have excellent charge/discharge performance and heavy duty ratio and can reduce recharging time by up to 30% compared with the current Maxell lithium ion rechargeable batteries.
Maxell has filed 55 patents regarding next generation electrodes such as nano-silicon composites developed so far.