Resource Center

Reactions with electrolyte can be detected using precise measurements of coulombic efficiency (CE) and charge end point capacity slippage. Three single-phase layered compositions in the Li-Mn-Ni-O system...

Three different cycling protocols including “continuous-cycling”, “barn-charge” and “cycle-store” were applied with an ultra high precision charger to Li[Ni0.42Mn0.42Co0.16]O2/graphite and/or Li[Ni1/3Mn1/3Co1/3]O2/graphite pouch cells tested using different upper cutoff potentials.

Twenty LiCoO2/Graphite cells with ages between 0 and 12 years having different cycling histories but identical chemistry and construction were obtained from Medtronic Inc. These cells presented a unique opportunity to learn about aging mechanisms in Li-ion cells.

In this study, coulombic efficiency versus charging rate was measured at different temperatures and for two cell types. Small changes to the coulombic efficiency during cycling resulting from small amounts of lithium plating during the charging process were detected using a high precision charger.

Determining the lifetime of Li-ion cells destined for decade-long applications is very challenging. Li-ion cells for long life applications fail because of parasitic reactions, occurring at tiny rates, between the electrolyte and the charged electrodes that are occurring all the time.

The capacity loss and coulombic efficiency of commercial LiCoO2/graphite Li-ion cells have been examined using high precision coulometry and long-term cycling tests. The experiments show that time, not cycle count, was the dominant contributor to the degradation of LiCoO2/graphite Li-ion cells cycled at low rates and elevated temperatures.

Here, we use entropy profiling to track ageing markers in the same way as differential voltage analysis. In addition to lithiation/delithiation hysteresis in the OCP of Gr-Si blends, cells with Gr-Si anodes also exhibit...