New system for storing lithium-polymer energy

The basque technology centre CIDETEC is working on a project about lithium-polymer energy with the collaboration of the companies CEGASA and ZIGOR.

Actually, they are in the first stage of the project. Initially, they analysed the structure, design and development of different electrode materials with multiple characteristics (cathode and anode) to use lithium-polymer in batteries.

The results of the project enabled the development of a lab-scale prototype of a rechargeable graphite-polypirrol battery. The area of that battery is 1,9 x 4,5 cm² and it can provide a energy density of 125 Wh/kg. If we compare those results with the dimensions of commercial lithium-ion batteries that use inorganic oxide of intercalation, the battery made by CIDETEC has slightly lower energy density values. However, if we take into account all the factors that can be modified during the chemical synthesis of polymer conductors, it seems possible to obtain electrodes that may have capacities close to the theoretical ones (450 Ah/kg). That would mean a great improvement of inorganic oxides of intercalation. At the present CIDETEC is trying to replace the liquid electrolyte with a solid electrolyte, which would transform its battery in an organic system.

The followings are the technological innovations that have been obtained until the present:

• Possibility to remove metallic lithium from secondary lithium batteries, high energy density and high average life (superior than 1000 cycles of loading and unloading)
• Reduction of weight and dimension, flexibility of design and processing, and all that associated with the use of polymer electrodes based on polymer conductors.
• Reduction of internal resistance and improvement of chemical stability and electrochemistry of the battery. The latter has been obtained thanks to the higher ionic conductibility of new poly-electrolytes, and that way, apart from extending the average life of the battery, it has been possible to include the modularity concept in the design.

The organic batteries made of the above mentioned characteristics are useful for applications where the weight of the battery is determining, such as in telephones, computers and mobile phones. Nowadays, those appliances are widely sold and it is foreseen an increase in their sales in the last years. Thanks to the organic batteries all those appliances may be easily recycled, eliminating the most toxic components of the present (such as inorganic oxides).