Safe Li-Ion Technology for Micro and Mild Hybrid application based on CEA Bipolar LiFePO₄/Li₄Ti₅O₁₂ technology

The bipolar design consists on identical cells which are stacked together. This technology offers several advantages because it simplifies cell-to-cell connections and so offers a lowering internal resistance for the whole battery. The bipolar battery can be designed to present a large capacity, a high voltage and an appreciable flexible form factor.
The patented bipolar battery developed in CEA for the Hybrid Electric Vehicle (HEV) is based upon the use of Li₄Ti₅O₁₂ as anode material (allowing the use of a common bipolar aluminium current collector, and high power application) and LiFePO₄ (cycle life, safety, low cost). The main target has been first to achieve a sealed system with no electrolyte leakage, and then to demonstrate the advantage of the Li₄Ti₅O₁₂ / LiFePO₄ couple (1.9V) for high power Li-ion bipolar battery. To increase the battery cycle life, a new design has been elaborated and has allowed to develop standard energy battery of 15Wh (24V, 0.65 Ah).
In this paper, first results on 15Wh cells, using the Li₄Ti₅O₁₂ / LiFePO₄ couple and a new bipolar battery design, will be presented according HEV profiles.