Identification of the Source of Evolved Gas in Li-Ion Batteries by Using 13C-Labeled Solvents

Abstract

Gas evolution in lithium-ion batteries at elevated temperature is a big problem to be solved for practical usage. In order to elucidate the mechanism of gas evolution, we employed 13C-labeled ethylene carbonate (13C-EC) and diethyl carbonate (13C-DEC) as solvent components. Evolved CO2 during storage were analyzed by GC/AED technique to determine the isotopic ratio. The relative proportions of the CO2 derived from EC, DEC, and non-solvent were determined to be 52%, 11%, and 37%, respectively. The main source of CO2 was found to be EC. Further storage tests with a single electrode showed that CO2 evolution also occurs from cathode components.

Understanding the Role of Alumina (Al2O3), Pentalithium Aluminate (Li5AlO4), and Pentasodium Aluminate (Na5AlO4) Coatings on the Li and Mn‐Rich NCM Cathode Material 0.33Li2MnO3·0.67Li(Ni0.4Co0.2Mn0.4)O2 for Enhanced Electrochemical Performance

“…During the charging above 4.25 V, a second wave of the CO 2 evolution is observed, reaching a maximum at 4.5 V. This phenomenon is attributed to the alkyl carbonate solvents decomposition. [ 68,69 ] At the constant voltage step of 4.7 V, there is a further increase in the CO 2 evolution that can be assigned to the interactions between the electrolyte solvents (FEC) and the oxygen extracted from the HE‐NCM lattice. [ 69,68 ] As expected, during the first charge, Na‐aluminate coated electrodes typically exhibited lower CO 2 evolution than the uncoated ones.…”

“…[ 68,69 ] At the constant voltage step of 4.7 V, there is a further increase in the CO 2 evolution that can be assigned to the interactions between the electrolyte solvents (FEC) and the oxygen extracted from the HE‐NCM lattice. [ 69,68 ] As expected, during the first charge, Na‐aluminate coated electrodes typically exhibited lower CO 2 evolution than the uncoated ones. However, the CO 2 evolution at the constant voltage step (4.7 V) is higher, which we found to be linked to the oxygen evolution trends.…”

“…The evolution of C 2 H 4 ( m / z = 28) at the beginning of the first charge is likely to be associated with the reductive decomposition of FEC from the electrolyte solution (Figure S9c, Supporting Information). [ 69,71 ] The lower evolution of the ethylene on the Na‐aluminate coated HE‐NCM cathode than the uncoated material indicates the suppression of electrolytic degradation at the electrode/electrolyte interface. Similar inference can also be made from the lower evolution of the POF 2 + fragment corresponding to the LiPF 6 degradation for the coated sample (Figure S9d, Supporting Information).…”

Chromatographic Techniques in the Research Area of Lithium Ion Batteries: Current State-of-the-Art

“…Formation AED [224] MS [195,218,225,226] TCD [57,196,227] n/a [228] Cyclic Aging FID [229] MS [230] TCD [229] n/a [231] Overcharge FID [152] FTIR [152,153] MS [232] TCD [153] n/a [233] Thermal Runaway/Abuse Conditions (ARC, etc.) FID [234] FTIR [198] MS [198,235] TCD [234,[236][237][238][239][240] VUV [217] n/a [241,242] Model Aging of LIB Components (Thermal; Radiolysis, etc.)…”

“…The cell format provides easy access to the emerging gas volume i.e., by directly puncturing the foil with a syringe. Onuki et al subsequently utilized a GC system with atomic emission detector (AED) to analyze the gases emerging from NCA-based cells with DEC/EC electrolyte stored at elevated temperatures [224]. Hydrogen, carbon monoxide and carbon dioxide were identified.…”