A high power bipolar Li-ion cell for HEV applications – Green Lion®

The Green Lion® project is dedicated to the valorisation of a specific Li-Ion technology developed by CEA and combining Bipolar architecture on Aluminium current collector and the use of 2 advance Li-Ion materials Lithium Iron Phosphate (LFP) at the positive electrode and Lithium Titanate (LTO) at the negative one.
The project especially aims the development of a Li-ion bipolar cell 15 Wh- 24V (which consists on 13 identical cells LFP / LTO stacked in bipolar design), previously designed by the CEA in a project funded by ADEME and named “PowerSafe”. Through the project Green Lion ®, CEA wishes to accomplish the necessary steps that will allow setting a pilot line for the bipolar cell assembly process.
The project will be split in four different tasks:
- the specifications of Bipolar 15Wh Li-Ion cells and 150Wh Battery Demonstrator. In addition, this task will include some benchmarking in order to always integrate the best components in the cells
- the second task will concentrate the main work with: i) the set-up of the pilot line and of all the required equipements and ii) the research concerning the main limitation of the technology which is linked to the risk of ionic micro-short-circuits between the monopolar cells stacked inside the bipolar architecture. The hard point of the technology is the choice of the sealing component (glue or resin) which will be used to seal each compartment and prevent electrolyte leakage between adjacent cells. An alternative way will be studied through the use of gel polymer electrolytes, that allows suppressing liquid electrolyte and so short-circuits. The main Milestone of the project will be to reach a selfdischarge below 10%/month, corresponding to conventional Li-Ion values.
- .the third task will start after receiving all the equipments defined in task 2 and will be dedicated to 15Wh cell manufacturing and testing, and also to the 150Wh battery demonstrator assembly and test
- In parallel, all along the program, helped by Valorisation direction of the CEA, all the inputs needed for valorisation will be completed, mainly:
o Intellectual property reinforcement, freedom of exploitation
o Market analysis in order to build the business plan
o Cost analysis and first data concerning Life Cycle Analysis

At the end of Green Lion® project, CEA will be able to either licence its technology to a battery manufacturer, especially for mass markets such as hybrid vehicles, either to create a start-up company to address some markets for which this low cost, safe and high power Li-Ion technology could be promising.