Mechanism of capacity fade of MCMB/Li1.1[Ni1/3Mn1/3Co1/3]0.9O2 cell at elevated temperature and additives to improve its cycle life

Aging Analysis of Graphite/LiNi1/3Mn1/3Co1/3O2Cells Using XRD, PGAA, and AC Impedance

“…[11][12][13]18,51 To examine the extent of transition metal deposition on the anode, PGAA was used to quantify the amount of deposited Ni, Mn, Co on harvested graphite anodes. Due to the large penetration depth of neutrons, PGAA examines the entire volume of the investigated anode samples.…”

“…[10][11][12][13] During cycling of graphite/NMC full-cells, transition metal dissolution from the NMC material is found to be a crucial factor controlling capacity fade. 11,12 In one of these studies, Zheng et al demonstrated that upper cutoff potentials of >4.3 V lead to transition metal dissolution from NMC and thus compromise cycling performance.12 Based on half-cell experiments, Gallus et al proposed that transition metal dissolution is promoted by an acidic corrosion reaction due to the presence of HF, 13 suggested to be produced by the reaction of LiPF 6 salt with trace water in standard electrolytes.14 Removal of transition metals from the NMC structure not only affects cathode performance (loss of active material and/or structural changes of the particle surface), but also strongly influences the anode through the deposition of dissolved transition metals on the graphite surface. Already small amounts of Ni, Mn, and Co on the anode can result in enhanced electrolyte decomposition and impedance rise of the cell.…”

“…7,9 Despite the improved safety and cycling performance of NMC material, operating NMC based cells (full-cells or half-cells) at elevated temperatures or at high charge potential leads to poor cycle life. [10][11][12][13] During cycling of graphite/NMC full-cells, transition metal dissolution from the NMC material is found to be a crucial factor controlling capacity fade. 11,12 In one of these studies, Zheng et al demonstrated that upper cutoff potentials of >4.3 V lead to transition metal dissolution from NMC and thus compromise cycling performance.…”

“…[10][11][12][13] During cycling of graphite/NMC full-cells, transition metal dissolution from the NMC material is found to be a crucial factor controlling capacity fade. 11,12 In one of these studies, Zheng et al demonstrated that upper cutoff potentials of >4.3 V lead to transition metal dissolution from NMC and thus compromise cycling performance. 12 Based on half-cell experiments, Gallus et al proposed that transition metal dissolution is promoted by an acidic corrosion reaction due to the presence of HF, 13 suggested to be produced by the reaction of LiPF 6 salt with trace water in standard electrolytes.…”

High Performance Lithium-Ion Batteries Using Fluorinated Compounds

“…Of particular interest here are two fluorinated additives, lithium difluoro[oxalato]borate (LiDFOB) [20,[37][38][39] and lithium tetrafluoro[oxalato] phosphate (LiTFOP) [40] (see Figure 1.6(b) and (c) for detailed molecular structures). Both additives can form a thermally more stable SEI layer on the surface of graphite to extend the life of graphite-based lithium-ion cells, but without adding extra interfacial impedance to the cells.…”