Comparative study of lithium bis(oxalato) borate and lithium bis(fluorosulfonyl) imide on lithium manganese oxide spinel lithium-ion batteries

The comparative study of lithium bis(oxalato) borate (LiBOB) and lithium bis(fluorosulfonyl) imide (LiFSI) used as an additive in the performance of lithium manganese oxide spinel (LiMn2O4) cathode was systematically investigated at elevated temperature. The results indicated that a solid-electrolyte interphase (SEI) film on cathode produced by the oxidation of the LiFSI additive is more robust and stable against Mn dissolution problem during cycling at 55 degrees C compared with the SEI formed by the oxidation of the Blank and the LiBOB-added electrolyte. LiFSI aids in stabilizing the electrolyte by trapping the PF5, i.e., sequestering the radical which tends to oxidize EC and DEC electrolyte solvents. Thus, oxidation is suppressed on the cathode, as evidenced by scanning electron microscopy (SEM), inductively coupled plasma- atomic emission spectrometry (ICP-AES) and X-ray photoelectron spectroscopy (XPS). As a result, HF generation is suppressed, which results in less Mn dissolution from the spinel cathode. (C) 2014 Elsevier B.V. All rights reserved.