Surface structural disordering in graphite upon lithium intercalation/deintercalation

JOURNAL OF POWER SOURCES

卷:195

Article

Sethuraman, Vijay A.¹  Hardwick, Laurence J.¹  Srinivasan, Venkat¹  Kostecki, Robert¹ 

[1] Univ Calif Berkeley, Lawrence Berkeley Lab, Environm Energy Technol Div, Berkeley, CA 94720 USA

关键词: Lithium-ion battery;    Graphite anode;    Structural disordering;    Capacity fade;    Raman spectroscopy;   

DOI  :  10.1016/j.jpowsour.2009.12.034

来源: Elsevier

【 摘 要 】

We report on the origin of the Surface structural disordering in graphite anodes induced by lithium intercalation and deintercalation processes. Average Raman spectra of graphitic anodes reveal that cycling at potentials that correspond to low lithium concentrations in LixC (0 <= x<0.16) is responsible for most of the structural damage observed at the graphite surface. The extent of surface structural disorder in graphite is significantly reduced for the anodes that were cycled at potentials where stage-1 and stage-2 compounds (x > 0.33) are present. Electrochemical impedance spectra show larger interfacial impedance for the electrodes that were fully delithiated during cycling as compared to electrodes that were cycled at lower potentials (U < 0. 15 V vs. Li/Li+). Steep Li+ surface-bulk concentration gradients at the surface of graphite during early stages of intercalation processes, and the inherent increase of the LixC d-spacing tend to induce local stresses at the edges of graphene layers, and lead to the breakage of C-C bonds. The exposed graphite edge sites react with the electrolyte to (re)form the SEI layer, which leads to gradual degradation of the graphite anode, and causes reversible capacity loss in a lithium-ion battery. Published by Elsevier B.V.

【 授权许可】

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