Neutron Depth Profiling Technique for Studying Aging in Li-ion Batteries
Robert G. Downing
During operation of a Li-ion cell, lithium diffuses in and out of the solid phase anode and cathode. Measuring the lithium transport within the cell over its operational life could provide key information for understanding the loss of active lithium and the associated aging mechanisms. Concentration profiles of lithium in a cell are difficult to measure with spectroscopic techniques. Here, neutron depth profiling was used to measure lithium nearsurface concentration profiles along the anode and cathode strips in off-the-shelf cylindrical Liion batteries as a function of the aging process. We have found buildup of the surface concentration of lithium in graphite anode as well as a general decrease in the intercalation efficiency in lithium iron phosphate cathode material with aging.