Author(s)

Christopher Betzin^1,2, Holger Wolfschmidt¹

¹Siemens AG, Erlangen, Germany.
²Friedrich-Alexander-University, Erlangen, Germany.

In this paper, commercial lithium ion battery cells consisting of graphite based anode and LiNi_0.80Co_0.15Al_0.05O₂ (NCA) oxide based cathode were investigated regarding their aging behavior. The capacity loss is dependent on the state of charge (SOC) whereas the battery is operated with partial cycles at defined SOCs. The structural change of the positive electrode material is identified as dominating aging process. Especially grid services such as primary control reserve are of economic interest for battery system operators. In this application, small charge and discharge cycles are the main operation mode. Considering the operation of single battery storage systems in a virtual storage power plant, different states of charges are much more of interest. Thus the battery aging behavior of lithium ion cells with NCA based cathode material with respect to cycling at specific state of charge with small depth of discharge (DOD) is investigated. The results in this paper provide understanding of small DOD cycling at given SOC behavior which is necessary for NCA lifetime prediction in this particular case, especially in virtual storage plant with various storage systems and thus various SOCs for delivery primary reserve the small DOD behavior which has an important impact on efficiency and economy. It is a key finding, which aging mechanisms are essential in order to optimize the cell operation and adapt it to system performance.

Cyclic Voltammetry, NCA, Fatigue of LiNCAO, Primary Control Reserve

Betzin, C. and Wolfschmidt, H. (2018) Ageing Behavior of LiNi_0.80 Co_0.15Al_0.05O₂ Cathode Based Lithium Ion Cells—Influence of Phase Transition Processes. Materials Sciences and Applications, 9, 155-173. doi: 10.4236/msa.2018.91011.