Development of a LiMnFePO 4 / Li 4 Ti 5 O 12 2Ah Pouch Cell: An Example of the Effective Integration of New Materials

One of the most promising approaches for limiting climate change is the use of alternative and greener sources of energy (wind, solar, etc.). The electricity generated from these sources fluctuates, however, and a storage solution is needed. The advent of energy storage for wind farms, solar plants, etc., requires a new generation of batteries. It is therefore imperative that a battery with high energy density, a longer life cycle and improved safety be developed. In this paper, we describe our efforts to develop a safe and long-life cycle LiMnFePO 4 (LMFP)/Li 4 Ti 5 O 12 (LTO) 2Ah pouch cell. One of the major challenges faced in this pursuit was gas evolution during cycling. Various side reactions with active materials resulted in the generation of gas during cycling. To circumvent this, we implemented several mitigation strategies. To combat electrolyte degradation (1.0 M LiPF 6 in carbonate solvents) due to Mn 2+ dissolution in LMFP, we integrated a new class of polymer as a binder in the cathode preparation, which effectively decreased the degradation during cycling. This polymer also has high voltage stability. 1 At the battery’s negative electrode, we developed a new carbon coating method on LTO that minimizes electrolyte degradation and optimizes high C-rate preformances, especially fast charging performances. 2 Although these new materials reduce gas evolution, they do not eliminate it. Therefore, we developed the first polymer capable of trapping the carbon dioxide, major component of gases generated during cycling and, in turn, preventing pouch cell inflation. This polymer was integrated in a pouch cell in the form of an insoluble trapping sheet. 3 Although relatively simple, this technology made the pouch cells safer. This unique approach is versatile and can be implemented in pouch cells with any type of chemistry when gas scavenging is required. The 2Ah pouch cells did not experience any inflation during extensive cycling and aging. Cells cycled more then 750 cycles at 45 o C with a rate of 1C – 1C before reaching 80% retention capacity. Reference (1) Daigle, J.-C.; Asakawa, Y.; Zaghib, K. Polymer additives and their use in electrode materials and electrochemical cells. WO2020061710A1, 2020. (2) Daigle, J.-C.; Asakawa, Y.; Beaupre, M.; Gariepy, V.; Vieillette, R.; Laul, D.; Trudeau, M.; Zaghib, K. Boosting Ultra-Fast Charge Battery Performance: Filling Porous nanoLi4Ti5O12 Particles with 3D Network of N-doped Carbons. Sci. Rep. 2019, 9 (1), 1-