posted on 2024-02-27, 22:08authored byTim Melin, Robin Lundström, Erik J. Berg
Electrolyte additives are indispensable to enhance the
performance
of Li-ion batteries. Lithium bis(oxalato)borate (LiBOB) has been explored
for many years, as it improves both cathode and anode performance.
No consensus regarding its reaction mechanisms has, however, been
established. A model operando study combining attenuated
total reflection infrared spectroscopy (ATR-FTIR), electrochemical
quartz crystal microbalance (EQCM), and online electrochemical mass
spectrometry (OEMS) is herein presented to elucidate LiBOB reduction
and electrode/electrolyte interphases thus formed. Reduction of the
BOB– ion sets in at ∼1.8 V with solid lithium
oxalate and soluble oxalatoborates as the main products. The reduced
BOB– ion also reacts with itself and its environment
to evolve CO2, which in turn impacts the interphase formed
on the negative electrode. This study provides further insights into
the reduction pathways of LiBOB and how they contribute to the interphase
formation.