アドバンスト・フォトン・ソースでバッテリーを長寿命化(Giving batteries a longer life with the Advanced Photon Source)

2024-09-13 アルゴンヌ国立研究所(ANL)

＜関連情報＞

• https://www.anl.gov/article/giving-batteries-a-longer-life-with-the-advanced-photon-source
• https://www.science.org/doi/10.1126/science.adg4687
• https://onlinelibrary.wiley.com/doi/abs/10.1002/aenm.201201059

層状正極における溶媒媒介酸化物水素化反応 Solvent-mediated oxide hydrogenation in layered cathodes

Gang Wan, Travis P. Pollard, Lin Ma, Marshall A. Schroeder, […], and Michael F. Toney
Science  Published:12 Sep 2024
DOI:https://doi.org/10.1126/science.adg4687

Editor’s summary

A limitation to the efficiency and reliability of lithium ion batteries is their tendency to self-discharge over time. Wan et al. used a series of experimental surface characterization methods and theoretical calculations on representative high-nickel-content cathodes to investigate the mechanism by which nickel at the surface is reduced compared with the bulk. They observed that the self-discharge was caused by the insertion of protons into the charged cathode, which was triggered by the decomposition of the electrolyte. This mechanism, based on a surface hydrogenation reaction, differs from the widely accepted model that is based on lithium diffusion from the electrolyte into the cathode. —Marc S. Lavine

Abstract

Self-discharge and chemically induced mechanical effects degrade calendar and cycle life in intercalation-based electrochromic and electrochemical energy storage devices. In rechargeable lithium-ion batteries, self-discharge in cathodes causes voltage and capacity loss over time. The prevailing self-discharge model centers on the diffusion of lithium ions from the electrolyte into the cathode. We demonstrate an alternative pathway, where hydrogenation of layered transition metal oxide cathodes induces self-discharge through hydrogen transfer from carbonate solvents to delithiated oxides. In self-discharged cathodes, we further observe opposing proton and lithium ion concentration gradients, which contribute to chemical and structural heterogeneities within delithiated cathodes, accelerating degradation. Hydrogenation occurring in delithiated cathodes may affect the chemo-mechanical coupling of layered cathodes as well as the calendar life of lithium-ion batteries.

高エネルギーX線回折を用いたLi1-x(Ni1/3Mn1/3Co1/3)0.9O2 の熱分解の研究 Study of Thermal Decomposition of Li1-x(Ni1/3Mn1/3Co1/3)0.9O2 Using In-Situ High-Energy X-Ray Diffraction

Zonghai Chen, Yang Ren, Eungje Lee, Christopher Johnson, Yan Qin, Khalil Amine
Advanced Energy Materials  Published: 11 March 2013
DOI:https://doi.org/10.1002/aenm.201201059

Abstract

Safety has been a major technological concern hindering the deployment of lithium-ion batteries for automobile applications. We investigated the decomposition mechanism of delithiated cathode materials at thermal abuse conditions using Li_1.1[Ni_1/3Mn_1/3Co_1/3]_0.9O₂ as a model cathode material. An in-situ high-energy X-ray diffraction technique was established as an alternative to conventional thermal analysis techniques like differential scanning calorimetry and accelerating rate calorimetry. The X-ray diffraction data revealed that the thermal decomposition pathway of delithiated Li_1-x[Ni_1/3Mn_1/3Co_1/3]_0.9O₂ strongly depended on the exposed chemical environment, like solvents and lithium salts. A phase transformation of dry delithiated Li_1-x[Ni_1/3Mn_1/3Co_1/3]_0.9O₂ was observed at about 278 °C, and its onset temperature was reduced to about 197°C with the presence of the electrolyte. It is suggested that the reduction in thermal stability is possibly related to proton intercalation into the delithiated material.