In Situ solvothermal synthesis of High-Energy Cathodes for Lithium-Ion Batteries

For the large-scale application of lithium-ion batteries in electric vehicles and grid-scale storage, it has been of great interest to develop cost-efficient solvothermal methods to synthesize high-energy electrodes. As synthesis is generally carried out in a sealed reactor, like a black box where the inputs and outputs are known, little is known about the intermediate phases and the overall reaction pathway. In addition, the synthesis condition is far from thermodynamic equilibrium, implying that the reactions and induced phase transformations often proceed along a kinetics-controlled pathway that excludes the feasibility of following synthesis reactions using ex-situ methods.  Herein, we report our latest results from development and application of in-situ techniques and capabilities for studying synthesis reaction in real time during preparing cathode materials (Fig. 1). Specific examples will be given on time-resolved XRD studies of solvothermal synthesis of high-energy polyanioic cathodes (i.e. LiFe_xMn_1-xPO₄, Li-V-PO₄),^{1, 2}to show how insights gained from these studies can be applied to gain precise control of the phase, stoichiometry and morphology. This research was supported by DOE-EERE under the Advanced Battery Materials Research (BMR) program, under Contract No. DE-SC0012704.

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[2] L. Wang, J. Bai, P. Gao, X. Wang, and F. Wang, Structure tracking aided design and synthesis of Li₃V₂(PO₄)₃ nanocrystals as high-power cathodes for lithium-ion batteries (submitted).