Influence of polymeric binders on mechanical properties and microstructure evolution of silicon composite electrodes during electrochemical cycling

Yikai Wang, Dingying Dang, Dawei Li, Jiazhi Hu, Yang Tse Cheng

Research output: Contribution to journalArticlepeer-review

39 Scopus citations

Abstract

Polymeric binders are a critical component to enhance mechanical integrity, maintain electronic conductivity, and achieve long durability of silicon (Si)-based electrodes. A fundamental understanding of the relationship between binder properties and mechanical degradation of Si electrodes is indispensable to developing durable Si-based electrodes. Using an environmental nanoindentation system, we measured the mechanical properties of Si composite electrodes made with different binders, including polyvinylidene fluoride (PVDF), Nafion, sodium-carboxymethyl cellulose (Na-CMC), and sodium-alginate (SA), as a function of the state-of-charge and cycle numbers under both dry and wet conditions. In contrast to electrodes made of Si alone, both elastic modulus (E) and hardness (H) of Si composite electrodes increase with lithium concentration within each cycle. E and H continuously decrease during long-term cycling. The mechanical property evolution of Si composite electrodes can be correlated with the porosity and irreversible thickness changes, which are largely determined by the mechanical properties of binders, instead of the adhesion between binders and Si. Electrodes under wet conditions have smaller E and H values than those under dry conditions because binders soften in the electrolyte. These findings not only provide useful mechanical parameters for battery modeling, but also may help design high performance and durable Si-based electrodes.

Original languageEnglish
Pages (from-to)170-178
Number of pages9
JournalJournal of Power Sources
Volume425
DOIs
StatePublished - Jun 15 2019

Bibliographical note

Funding Information:
This work is partially supported by the National Science Foundation Award 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 Battery Materials Research (BMR) Program under Contract Number DE-EE0007787 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 .

Funding Information:
This work is partially supported by the National Science Foundation Award 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 Battery Materials Research (BMR) Program under Contract Number DE-EE0007787 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.

Publisher Copyright:
© 2019 Elsevier B.V.

Keywords

  • Electromechanical degradation
  • Mechanical property
  • Nanoindentation
  • Polymeric binder
  • Porosity
  • Silicon electrode

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Energy Engineering and Power Technology
  • Physical and Theoretical Chemistry
  • Electrical and Electronic Engineering

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