Temperature Dependence of Oxygen Release from LiNi0.6Mn0.2Co0.2O2 (NMC622) Cathode Materials for Li-Ion Batteries
By Roland Jung, P. Strobl, F. Maglia, C. Stinner, H. Gasteiger. 2018
146 citations recorded by the source corpus.
Promising cathode materials for Li-ion batteries are layered transition metal oxides (LiNi x Mn y Co z O 2 , NMC). Here, we will investigate the temperature dependence of oxygen release from NMC622, caused by the transformation of the near-surface structure from the layered to spinel and/or rock-salt structure. We will demonstrate that oxygen release is not a potential driven process but occurs once ∼ 81% of the lithium ions are removed from the NMC structure. Consequently, the onset potential for oxygen release in NMC-graphite cells decreases only by ∼ 60 mV from 4.42 V at 25 ◦ C to 4.36 V at 50 ◦ C, which is simply due to lower overpotentials at higher temperature. The amount of evolved oxygen increases significantly with increasing temperature, indicating the formation of thicker spinel/rock-salt surface layers. As the released oxygen causes chemical oxidation of the electrolyte, the amounts of CO 2 and CO occurring simultaneously with O 2 release also increase with temperature. Further experiments in NMC-Li cells as well as with 13 C-labelled ethylene carbonate (EC) electrolyte show that CO 2 evolved prior to O 2 release results from i) EC hydrolysis and ii) electrolyte impurity oxidation. In agreement with the onset potentials for oxygen release, we will show that stable cycling of NMC622-graphite full-cells is possible at the different temperatures up to ∼ 81% state-of-charge. © The Attribution
Subfields: Automotive Engineering, Electrical and Electronic Engineering
View Paper: https://www.semanticscholar.org/paper/62b56e184015b5da1642ee0c80dbc378a6b182d1
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Citations in the corpus
- Degradation Mechanisms and Mitigation Strategies of Nickel-Rich NMC-Based Lithium-Ion Batteries (2019, background): “[88] have experimentally shown three other mechanisms that may contribute to CO2 emission, including solvent hydrolysis (if trace amounts of OH− exist), electrolyte impurity oxidation and HF reacting with lithium carbonate as a surface impurity.”
- Stabilizing Effect of a Hybrid Surface Coating on a Ni-Rich NCM Cathode Material in All-Solid-State Batteries (2019, background): “25,43 Also, as expected, only minor CO 2 evolution (comparable to the Li 2 CO 3 /LiNbO 3 -coated NCM622 cell) was observed for the bare NCM622 ( Figure S7 ), underlining the stabilizing effect of the hybrid coating.”