Investigating the Path Dependent Aging Behavior of Nickel Cobalt Aluminum Oxide Cathode Batteries During High C-rate Cycling Conditions

Nickel-rich cathode material batteries such as the nickel cobalt aluminum oxide with graphite anode are common in the automotive sector due to their high energy density and power performance capabilities, however, they are limited in lifetime performance. Accelerated degradation in specific operation conditions, such as high C-rates are known to significantly contribute to this issue. To better understand a chronological dependence of these high-stress conditions occurring during battery lifetime, a path dependent aging study is performed using profiles inspired by high-performance race operation. The focus on C-rates >1C during charging and discharging using real-world inspired profiles- known to induce particle cracking or lithium plating- addresses the need to understand aging behavior in less studied, but highly relevant high-performance automotive context. The aging conditions were tailored to induce specific degradation modes to better identify potential degradation mode coupling. Using differential voltage and capacity analysis techniques, degradation modes were identified which likely contributed to path dependent aging behavior, including loss of lithium inventory and loss of active material in the positive electrode. Two critical paths were identified in this study where later high C-rate conditions in the form of fast-charging at temperatures of 25 °C resulted in accelerated aging and where loss of lithium inventory induced stresses in the positive electrode, accelerating loss of active material.