Mechanical degradation is largely responsible for the short cycle life of silicon (Si)-based electrodes for future lithium-ion batteries. An improved fundamental understanding of the mechanical behavior of Si electrodes, which evolves, as demonstrated in this paper, with the state of charge (SOC) and the cycle number, is a prerequisite for overcoming mechanical degradation and designing high capacity and durable Si-based electrodes. In this study, Young's modulus (E) and hardness (H) of Si composite electrodes at different SOCs and after different cycle numbers are measured by nanoindentation under both dry and wet (liquid electrolyte) conditions. Unlike electrodes made of Si alone, E and H values of Si composite electrodes increase with increasing Li concentration. The composite electrodes under wet conditions are softer than that under dry conditions. Both E and H decrease with the cycle number. These findings highlight the effects of porosity, liquid environment, and degradation on the mechanical behavior of composite electrodes. The methods and results of this study on the mechanical property evolution of Si/polyvinylidene fluoride electrodes form a basis for exploring more effective binders for Si-based electrodes. Furthermore, the evolving nature of the mechanical behavior of composite electrodes should be taken into consideration in future modeling efforts of porous composite electrodes.
|Advanced Energy Materials
|Published - Apr 5 2018
Bibliographical noteFunding Information:
This work was supported by the National Science Foundation under Cooperative Agreement No. 1355438. The authors also acknowledge the support by the Assistant Secretary for Energy Efficiency and Renewable Energy, Vehicle Technologies Office of the U.S. Department of Energy under Contract No. DE-EE0007787 under the Battery Materials Research (BMR) Program and the financial support from the Alliance for Sustainable Energy, LLC, Managing and Operating Contractor for the National Renewable Energy Laboratory for the U.S. Department of Energy. D.L. would like to acknowledge the support of China Scholarship Council.
© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
- Si composite electrode
- mechanical properties
- state of charge (SOC)
ASJC Scopus subject areas
- Renewable Energy, Sustainability and the Environment
- Materials Science (all)