Ceren Zor of Professor Peter Bruce's research group collaborated with Yaprack Subasi of Koc University and researchers at Gebze Technical University to improve the stability issues of Lithium bis(oxalate) borate, LiB(C204) (LiBOB) for use in Li-ion batteries.
In this paper, published in ACS Publications, they report a high purity water free LiBOB synthesised with a reduced number of processing steps, employing lithium carbonate, oxalic acid, and boric acid as low-cost starting materials, and via ceramic processing methods under a protective atmosphere.
The physical and chemical characterisations of both anhydrous and monohydrate phases were performed with X-ray powder diffraction (XRPD), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy and scanning electron microscopy (SEM) analyses to determine the degree of purity and the formation of impurities, such as LiBOB H2O, HBO2 and Li2C2O4, as a result of the aging investigations where the as-synthesised salt was exposed to ambient conditions for different durations.
Differential thermal analysis (DTA) was applied to determine the optimum synthesis conditions for anhydrous LiBOB and to analyse the water loss and the decomposition of LiBOB H2O.
Aging experiments with the water free LiBOB were carried out to evaluate the effect of humidity on the phase changes and resulting impurities under various conditions. The detrimental effect of even the slightest humidity condition was recorded, and this paper discusses the protective measures during and after the synthesis of LiBOB.
In this paper the authors explain that anhydrous LiBOB could be widely used as an electrolyte additive to improve the overall electrochemical performances for LIBs through development of a protective solid electrolyte interface (SEI) on the surface of high voltage cathodes, and by bringing about superior electrochemical properties with increased cycling stability, rate capability and Coulombic efficiency, if synthesised, purified and handled properly before use in real electrochemical systems.