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Performance Evaluation of the LiFePO4OH Cathode for Stationary Storage Applications Using a Reduced-Order Electrochemical Model

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journal contribution
posted on 14.01.2021, 04:13 by Lalit Sharma, Sagar Bharathraj, Prabeer Barpanda, Shashishekar P. Adiga, K. Subramanya Mayya
The development of inexpensive and large-capacity energy storage solutions is critical to support future electric grids for grid stability as well as to solve the intermittency of renewable generation. As the cost of stored energy per cycle is a primary concern as compared to the energy density in these applications, low cost and easy-to-produce battery active materials are intensely explored. In this pursuit, hydroxyphosphate-based materials have also been studied where tavorite LiFePO4OH has grasped attention. Though the material exhibits lower redox potential and thus offers lower energy density, it is still very attractive for stationary (grid) storage applications as it consists of earth-abundant elements. To evaluate the performance characteristics of this system, we establish an electrochemical reduced-order model and validate it against experiments. Based on this model, the effects of cell design parameters, electrode thickness, active material loading, and particle size, on battery performance, including the trade-off between energy and power capabilities were investigated by generating Ragone plots. While it was found that all three parameters have a significant effect on energy and power capabilities, a cathode particle of >2 μm would affect the power capability adversely because of the slow solid-state diffusion. Furthermore, the energy efficiency of the system was evaluated to be >82.5%, making it very attractive for stationary applications from the cost per unit energy stored perspective. These results highlight the commercial viability of hydroxyphosphate battery chemistry.