Novel environmentally friendly production methods for improved Li-ion batteries

The Li-ion battery technology is already highly developed and is currently the leading battery technology for portable electronic equipment. But there is still room for improvement, both within materials properties and production processes. This project has two parts and therefore two main goals, one which is to improve the materials properties of the electrode materials used in Li-ion batteries. The other goal is to modify the electrode production process to make it more environmentally friendly. The former goal we have in fact achieved by investigating a completely new anode material. This material is based on diatoms harvested from the ocean. These are naturally nanostructured materials made of silicon dioxide. The materials can be used with very little pre-treatments. These materials are then combined with new water soluble binders based on alginates. The new binder materials make the production of the electrodes much more cost efficient and more environmentally friendly. The results achieved with these materials can potentially increase the total capacity of a full battery cell by up to 40%. We are now working on a patent application to patent the material and the production process.

There are continuous global challenges related to emissions and security of supply of energy. The ambition of the European Strategic Energy Technology Plan (SET-plan) is within 2020 to reduce GHG emissions by 20%, increase amount of renewable energy sourc es in the energy mix to 20%, and reduce the primary energy use by 20%. Many solutions are proposed in order to reach this goal, and improvements in both stationary and portable energy storage will play significant roles on the path to success. With this i n mind, the battery research group at NTNU in Trondheim has for the past few years worked on development of new electrode materials for Li-ion and Mg-ion batteries based on benign and abundant elements as well as developing new and more environmentally fr iendly synthesis routes, particularly for cathode materials. On the road to developing more environmentally friendly batteries, it is necessary to consider the materials used to fabricate the electrodes such as binders and solvents. Currently, the most co mmon binder used is poly-vinylidene fluoride (PVDF) which must be dissolved in N-methyl-2-pyrrolidene (NMP). NMP have amongst other things been identified as a reproductive toxicant and long term exposure can be quite harmful. It is therefore desirable to replace NMP with another solvent. In order to achieve this, it is necessary to find other suitable binders which can be dissolved in less toxic and more environmentally friendly solvents. The first part of this project will therefore focus on finding alt ernative solutions to binder materials. The second part of this project will be to continue the development of Li2FeSiO4/C as cathode material. The main focus will be on improving the electronic and ionic conductivities of the material, which will be done by attempting to replace small amounts of Si with elements such as V, Al and P.