Engineering topics
Publications and source records attributed to Gittleson, Forrest S..
Transition metal d-states and oxygen p-states overlap and oxygen lattice integrity dictates the oxygen redox reversibility in metal substituted Li 2 RuO 3 positive electrodes for Li-ion batteries.
Layered lithium nickel, manganese, and cobalt oxides (NMC) are among the most promising commercial positive electrodes in the past decades. Understanding the detailed surface and bulk redox processes of Ni-rich NMC can provide useful insights into material design options to boost reversible capacity and cycle life. Both hard X-ray absorption (XAS) of metal K-edges and soft XAS of metal L-edges collected from charged LiNi 0.6 Mn 0.2 Co 0.2 O 2 (NMC622) and LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811) showed that the charge capacity up to removing ~0.7 Li/f.u. was accompanied with Ni oxidation in bulk and near the surface (up to 100 nm). Of significance to note is that nickel oxidation is primarily responsible for the charge capacity of NMC622 and 811 up to similar lithium removal (~0.7 Li/f.u.) albeit charged to different potentials, beyond which was followed by Ni reduction near the surface (up to 100 nm) due to oxygen release and electrolyte parasitic reactions. Overall, this observation points toward several new strategies to enhance reversible redox capacities of Ni-rich and/or Co-free electrodes for high-energy Li-ion batteries.
An ionic liquid comprising a cationic chemical species and an anionic chemical species. The cationic chemical species comprising a nitrogen containing moiety and a partially fluorinated alkyl chain moiety, wherein the partially fluorinated alkyl chain moiety is bonded to a nitrogen atom of the nitrogen containing moiety. The ionic liquid can be used as an electrolyte, as an additive to an organic solvent, as a lubricant, as a hydrophobic coating, as a treatment for fluorinated pollutants, as an electrolyte for sensor applications, as a stabilizing additive for existing battery electrolytes, and as an emulsifier.