Elisabeth Dupuis

IN SITU SEM ANALYSIS OF LITHIUM METAL POLYMER BATTERY

Lithium metal polymer battery (LMP) is an “all solid” energy storage technology that uses only very light components. This leads to a very high energy/weight ratio making it one of the best candidates for use in both electric and hybrid cars. The main physical characterisation tool used is the SEM because the total thickness of a unit cell is less than 100μm. SEM characterisation has played a key role in the discovery of the causes for certain types of failure modes (ex.: dendritic growth on the anode, dissolution of cathode materials in the electrolyte, etc.). However, for “dynamic failure modes”, like power fades and area specific impedance (ASI) increases, in-situ characterization (i.e. characterization of a cell during cycling) must be preferred. This work will present in-situ SEM analysis techniques applied to LMP cells. Attention will be given mainly to the lithium plating and unplating processes, to the salt gradient concentration during cycling and to the evolution of morphology during lithium plating and unplating.