Mechanochemical Engineering of Polymer-Coated Silicate Nanocrystal Cathodes

Lithium iron silicate has attracted a lot of attention due to its 330 mAh g-1 theoretical capacity (2 Li+ per formula unit). However, inherently it exhibits relatively poor Li-ion intercalation kinetics, interfacial reactivity and complex phase transitions resulting in lower than one Li+ storage and poor capacity retention. In this work, we report a core-shell strategy to overcome these obstacles making use of mechanochemical processing and polymer coating. Mechanochemical annealing has been sown recently [1] to lead to activation of Li-ion diffusion (DLi) by one order of magnitude enhancement. Subsequently, in situ conductive polymer coating was employed on the surface of nanocrystals via an ambient temperature chemical process. As a result of this integrated nanocrystal engineering approach the core-shell LFS@P (βII ) cathode material delivered >1.3 Li and substantially enhanced cycling stability. [1] Rasool, M.; Chiu, H. C.; Lu, X.; Voisard, F.; Gauvin, R.; Jiang, D.; Paolella, A.; Zaghib, K.; Demopoulos, G. P., Mechanochemically-tuned structural annealing: a new pathway to enhancing Li-ion intercalation activity in nanosized βII Li2FeSiO4. J. Mater. Chem. A 2019, 7, 13705-13713