Harbinger of hysteresis in lithium-rich oxides: Anionic activity or defect chemistry of cation migration

JOURNAL OF POWER SOURCES

卷:471

Article

Croy, Jason R.¹  Garcia, Juan C.¹  Iddir, Hakim¹  Trask, Stephen E.¹  Balasubramanian, Mahalingam² 

[1] Argonne Natl Lab, Chem Sci & Engn Div, Argonne, IL 60439 USA

[2] Argonne Natl Lab, Xray Sci Div, Adv Photon Source, Argonne, IL 60439 USA

关键词: Lithium rich;    Hysteresis;    Anion redox;    Oxygen redox;    Disordered rock salt;    XAS;    XANES;    XAFS;    DFT;   

DOI  :  10.1016/j.jpowsour.2020.228335

来源: Elsevier

【 摘 要 】

This work presents findings on the mechanisms of hysteresis in lithium-rich cathode oxides. It is generally reported that the energy inefficiency, observed during electrochemical cycling of Li-rich electrodes, is a direct result of anion redox processes. Similarly, the coupled phenomenon of cation migration has been cited as being a mere consequence of that process with no essential ramification to hysteresis. Such works, however, have only shown correlations and not causation. Specifically, studies that clearly preclude the complete absence of either anion redox or cation migration (down to defect-level concentrations) are not reported yet. Herein, we present first principles calculations and experimental data on a bespoke Li-rich system that is indubitably immune to oxygen activity but yet exhibits significant energy inefficiency. Additionally, the results directly implicate transition metal migration as the fundamental, sole process responsible for hysteresis in this material. This study is of particular importance to the design and development of new Li-rich materials aimed at eliminating the role of oxygen and enhancing the effective cationic redox contribution to the capacity and points out the essential need to develop materials devoid of transition metal migration to interstitial sites in both layered and disordered oxides alike.

【 授权许可】

Free