With an increasing demand for high-energy-density
lithium-ion batteries
(LIBs), nickel-rich cathodes such as LiNi0.9Mn0.05Co0.05O2 (NMC90) have gained significant interest
due to their relatively low cobalt and high specific energy. However,
cycling stability is compromised due to parasitic reactions at the
electrode–electrolyte interfaces of NMC90. Herein, we demonstrate
improved electrochemical properties of NMC90 using di-tert-butylmethyl adamantoyl silane (RSiCOAd: R is tBu(CH3)2 and Ad is 1-Ad) as an additive in a commercial electrolyte.
Upon detailed electrochemical and spectroscopic analysis, we demonstrate
that the RSiCOAd additive undergoes in situ decomposition to form
a fluorinated organosiloxane passivation layer on the NMC90 surface
and enhanced fluorination on the lithium anode surface. This phenomenon
could significantly mitigate the parasitic reactions at the cathode–electrolyte
interface while improving the electrochemical performances. Furthermore,
the practical viability of the RSiCOAd additive is evaluated by full-cell
studies with the graphite anode. After prolonged 200 cycles, full
cells containing RSiCOAd with the incorporation of just 1% additive
demonstrate an impressive ∼10% higher capacity retention, outperforming
pristine NMC90 full cells.