Existing methods to estimate the amount of Li in batteries rely on capacity measurements, describing how much charge a battery can hold, and coulombic efficiency values, which indicate how much charge a battery retains during cycles. Yet these measurements are not always accurate, as they do not account for unpredictable side reactions, self-discharge, and other effects affecting a battery's performance. "The primary objective of our study was to find a reliable methodology to compare battery testing data and operating results from various sources and conditions, as this could help to advance battery technology and development," Boryann Liaw, co-author of the paper, told Tech Xplore. "The conventional battery capacity analysis is empirical, heavily relying on test protocols and conditions, lacking a reliable framework for comparison. This work provides a thermodynamic framework and methodology that can compare data from across the board consistently." Leveraging the theoretical capacity of a transition metal oxide, the researchers were able to reliable estimate how much Li was in a battery's electrode. This allowed them to monitor small changes in the composition at the interface between a battery's electrode and electrolyte. As part of their study, Liaw and his colleagues used a total of 12 Li-NMC (layered transition metal oxide cathode material) cells with various chemical formulations and structural configurations, under a wide range of conditions. The results they collected were used to demonstrate a matrix that is traditionally difficult to perform, outlining a quantitative comparison among these cells. "We introduced a reliable fundamental thermodynamic framework and methodology that can compare various battery test data from across the board in a rationalized quantitative manner," Liaw said. "This approach can substantially reduce resources for battery testing and time to market, enable effective and reliable battery... |