Setting up the Reference Performance Tests of an Ageing Campaign for Non-Intrusive Diagnosis on Li4Ti5012 and LiMn1-XFexPO4 Based Cells

Abstract

Non-intrusive diagnosis and prognosis methods are increasingly adopted to track Li-ion batteries ageing without additional cost due to destructive processes for post-mortem analyses. To qualify and quantify internal degradation mechanisms of a cell, Incremental Capacity Analysis (ICA) and Differential Voltage Analysis (DVA) have proven themselves to provide precise outputs on the battery state of health. These differential methods require close-to-equilibrium Open Circuit Voltage (cte-OCV) measurements to decipher ageing paths depending on the utilization.This poster presents an ageing campaign preliminary study on some Graphite//LiMn1-xFexPO4 and Li4Ti5O12/Ni1-x-yMnxCoyO2 based cells. It focuses on the reference performance tests chosen to be the most complete on both cell and electrode levels.As the battery cte-OCV measurement is a lengthy process of at least 25h, the reference tests should be well-defined to acquire as many data as possible in a single shot. A comparison is carried between constant current measurements and incremental charges with relaxation (GITT) to approach thermodynamic equilibrium, as well as the conditions and sampling rates to leverage differential method curves without further smoothing.The electrode study is implemented as references for models to evaluate both thermodynamic and kinetic behaviours of the battery components. To find out the closest half-cell replicates, electrode versus lithium coin cells are compared with a 3 electrodes PAT-cell assembly depending on the temperature and measurements.