Investigation of 40 Ah Prismatic Batteries Operating Under Fast-Charge Conditions Using Operando Synchrotron XRD Technique

Abstract

The pressing challenges posed by the energy crisis and the impact of climate change have forced a gradual replacement of traditional internal combustion engine (ICE) automobile powertrains with electrochemical energy storage devices. However, a boost of the electric vehicles (EVs) market, by significant battery performance enhancements are consistently required, primarily due to numerous persistent concerns. One of the key features targeted by battery and EVs industries is the rapid charging capability, making EVs more competitive with the quick refueling of traditional gasoline vehicles. Notably, despite the clear benefits of fast charging technology, the accelerated battery degradation after fast and extreme fast charging raises on top of the drawbacks of this technology. Therefore, understanding of heterogeneity and structural transformations within battery systems is of high interest.In this regard, we attempt to investigate the structural properties of a LiNi1/3Mn1/3Co1/3O2 (NMC111) /graphite fresh industrial prismatic cell using synchrotron XRD under fast charge conditions. The investigated battery is a PHEV cell with an experimental capacity of 40 Ah. It was taken from a range rover vehicle pack after being disassembled. The evolution of the composite anode and cathode structures was followed by operando wide-angle X-ray scattering (WAXS). Using this approach, we were able to measure and quantify the different phases of graphite and NMC111 lithiation/delithiation at various potentials by analyzing the corresponding Bragg peaks. By that, we were able to detect some heterogeneities in the degree of lithiation/delithiation within the cell upon charge. In addition, a comparison between a fresh cell and another aged cell, with a state of health (SOH) of 88%, was made in order to investigate the effect of aging under fast charging conditions on the performance of the industrial LIBs.