Currently, the rare metal cobalt is a component of cathodes in high capacity and high-voltage lithium rechargeable batteries for electric vehicles (EVs) and home storage batteries.

As these devices become more popular, there are concerns regarding future shortages of cobalt used in rechargeable lithium-ion batteries. Significant cost increases are also expected, generating interest in abundant and cheap iron to replace cobalt as the constituent element in rechargeable batteries. However, iron could not offer voltage comparable to that of cobalt-based materials.

Now Fujitsu Laboratories has discovered a new factor that can improve the voltage of iron-based materials. Using a proprietary materials design technology as well as a technology that precisely controls the composition of raw materials and the formation process of materials, Fujitsu Laboratories has successfully synthesized lithium iron pyrophosphate (Li5.33Fe5.33(P2O7)4). This phosphate-based material has a voltage of 3.8 V, comparable to that of existing cobalt-based materials.

In the future, Fujitsu Laboratories will seek to improve the performance of cathodes using this newly developed iron-based material. By advancing the design of new crystal structures that can maintain a high voltage state for longer periods, Fujitsu Laboratories aims to develop cathode materials that offer high energy density comparable to cobalt-based materials.

In this way, Fujitsu Laboratories will contribute to lowering the cost of lithium rechargeable batteries and the devices that use them.