Dataset Information

Thermal Decomposition Study on Li2O2 for Li2NiO2 Synthesis as a Sacrificing Positive Additive of Lithium-Ion Batteries.

ABSTRACT: Herein, thermal decomposition experiments of lithium peroxide (Li2O2) were performed to prepare a precursor (Li2O) for sacrificing cathode material, Li2NiO2. The Li2O2 was prepared by a hydrometallurgical reaction between LiOH·H2O and H2O2. The overall reaction during annealing was found to involve the following three steps: (1) dehydration of LiOH·H2O, (2) decomposition of Li2O2, and (3) pyrolysis of the remaining anhydrous LiOH. This stepwise reaction was elucidated by thermal gravimetric and quantitative X-ray diffraction analyses. Furthermore, over-lithiated lithium nickel oxide (Li2NiO2) using our lithium precursor was synthesized, which exhibited a larger yield of 90.9% and higher irreversible capacity of 261 to 265 mAh g-1 than the sample prepared by commercially purchased Li2O (45.6% and 177 to 185 mAh g-1, respectively) due to optimal powder preparation conditions.

SUBMITTER: Kim J

PROVIDER: S-EPMC6943730 | biostudies-literature | 2019 Dec

REPOSITORIES: biostudies-literature

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Thermal Decomposition Study on Li2O2 for Li2NiO2 Synthesis as a Sacrificing Positive Additive of Lithium-Ion Batteries.

Kim Jaekwang J Kang Hyunchul H Hwang Keebum K Yoon Songhun S

Molecules (Basel, Switzerland) 20191217 24

Herein, thermal decomposition experiments of lithium peroxide (Li2O2) were performed to prepare a precursor (Li2O) for sacrificing cathode material, Li2NiO2. The Li2O2 was prepared by a hydrometallurgical reaction between LiOH·H2O and H2O2. The overall reaction during annealing was found to involve the following three steps: (1) dehydration of LiOH·H2O, (2) decomposition of Li ...[more]

PMID: 31861185

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Project description:Preventing the decomposition reactions of electrolyte solutions is essential for extending the lifetime of lithium-ion batteries. However, the exact mechanism(s) for electrolyte decomposition at the positive electrode, and particularly the soluble decomposition products that form and initiate further reactions at the negative electrode, are still largely unknown. In this work, a combination of operando gas measurements and solution NMR was used to study decomposition reactions of the electrolyte solution at NMC (LiNi x Mn y Co1-x-y O2) and LCO (LiCoO2) electrodes. A partially delithiated LFP (Li x FePO4) counter electrode was used to selectively identify the products formed through processes at the positive electrodes. Based on the detected soluble and gaseous products, two distinct routes with different onset potentials are proposed for the decomposition of the electrolyte solution at NMC electrodes. At low potentials (<80% state-of-charge, SOC), ethylene carbonate (EC) is dehydrogenated to form vinylene carbonate (VC) at the NMC surface, whereas at high potentials (>80% SOC), 1O2 released from the transition metal oxide chemically oxidises the electrolyte solvent (EC) to form CO2, CO and H2O. The formation of water via this mechanism was confirmed by reacting 17O-labelled 1O2 with EC and characterising the reaction products via 1H and 17O NMR spectroscopy. The water that is produced initiates secondary reactions, leading to the formation of the various products identified by NMR spectroscopy. Noticeably fewer decomposition products were detected in NMC/graphite cells compared to NMC/Li x FePO4 cells, which is ascribed to the consumption of water (from the reaction of 1O2 and EC) at the graphite electrode, preventing secondary decomposition reactions. The insights on electrolyte decomposition mechanisms at the positive electrode, and the consumption of decomposition products at the negative electrode contribute to understanding the origin of capacity loss in NMC/graphite cells, and are hoped to support the development of strategies to mitigate the degradation of NMC-based cells.

Dataset Information

Thermal Decomposition Study on Li2O2 for Li2NiO2 Synthesis as a Sacrificing Positive Additive of Lithium-Ion Batteries.

Publications

Thermal Decomposition Study on Li<sub>2</sub>O<sub>2</sub> for Li<sub>2</sub>NiO<sub>2</sub> Synthesis as a Sacrificing Positive Additive of Lithium-Ion Batteries.

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