Resource Center

Twenty seven LiCoO2/graphite wound prismatic cells containing a variety of electrolyte additives as well as high or low surface area LiCoO2 were studied during high temperature storage using an automated storage 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.

Eventual rapid capacity loss or "rollover" failure of lithium-ion cells during long-term cycling (>3000 cycles in many cases) at room temperature was studied with Li[Ni0.5Mn0.3Co0.2]O2/graphite pouch cells.

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.

This paper shows that accurate measurements of coulombic efficiency (CE) and impedance spectra of Li-ion batteries, that take a few weeks to acquire, can be used to rank the resulting lifetime of Li-ion cells.

In this work, the effect of the heat-treatment temperature of synthetic (artificial) graphite on the electrochemical performance of LiNi0.5Mn0.3Co0.2O2/graphite pouch cells was explored and compared with cells utilizing commercial-grade artificial and natural graphite materials

The method presented here is designed to allow a quantitative ranking among different materials to be made from tests on coin half cells, that can be translated to form a qualitative lifetime prediction in full cells.