In Situ Acoustic Diagnostics of Particle-Binder Interactions in Battery Electrodes

Netanel Shpigel, Sergey Sigalov, Mikhael D. Levi, Tyler Mathis, Leonid Daikhin, Alar Janes, Enn Lust, Yury Gogotsi, Doron Aurbach

Research output: Contribution to journalArticlepeer-review

29 Scopus citations

Abstract

The high phase-transformation strain developed upon intercalation in the host particles of a composite battery electrode affects the polymeric binder network mechanically, deteriorating the electrode cycling performance. Here, electrochemical quartz crystal microbalance with dissipation monitoring (EQCM-D) is used to demonstrate a new strain-accommodation mechanism, in high-strain NaFePO4/PVdF electrodes, via relaxation of the binder network surrounding the intercalation particles. Complete mechanical degradation of the polymer network occurs during long-term cycling of NaFePO4 electrodes in aqueous solutions (hard and tough behavior). In contrast, in aprotic solutions, a softened binder easily accommodates the high transformation strain, ensuring excellent electrode cycling performance (soft and tough behavior). Quantification of the high-frequency viscoelastic properties of an operating composite electrode linked to the binder's fracture toughness ensures fast and facile screening of the optimal polymeric binder/electrolyte solution combinations. This methodology should be extremely important for optimization of cycling performance of Li-Si anodes undergoing huge volume changes during cycling. Almost all practical composite battery electrodes experience volume changes during cycling, deteriorating their cycling performance. A new key element that the EQCM-D methodology introduces into the energy storage field is a general platform for quantification of high-frequency viscoelastic characteristics of high-strain composite electrodes correlated with their low-frequency resilience and toughness moduli. Fast relaxation ensures effective high-strain accommodation by softened binder in aprotic solution. In contrast, with excessively stiff binder in aqueous solution, the strong electrode/binder interactions tracked dynamically reflect the initial and advanced stages of the mechanical degradation of the polymeric binder up to its complete destruction. The discovered correlation between the fracture toughness of the binder and its high-frequency viscoelastic behavior will serve for a rational design of extremely strained composite alloy-type electrodes such as the Li-Si anode. Tough and brittle characters of the binder in composite battery electrodes stabilize/deteriorate their long-term cycling performance, respectively. Instead of performing conventional long-time cycling tests of battery electrodes followed by their postmortem analysis, the proposed accelerated EQCM-D diagnostic easily distinguishes between the stable and failed cycling modes of strained electrodes by characteristic coupled shifts in the recorded resonance frequency and resonance bandwidth changes on multiple harmonics (EQCM-D signatures).

Original languageEnglish
Pages (from-to)988-1003
Number of pages16
JournalJoule
Volume2
Issue number5
DOIs
StatePublished - 16 May 2018

Bibliographical note

Publisher Copyright:
© 2018 Elsevier Inc.

Funding

The authors acknowledge funding from the Binational Science Foundation grant no. 2014083/2016 and the Israel Ministry of Science Technology and Space (grant 66032 ) for financial support. N.S. thanks the Israel Ministry of Science Technology and Space for its support. A.J. and E.L. thank the EU through the European Regional Development Fund (Centers of Excellence, 2014-2020.4.01.15-0011 and 3.2.0101-0030 ), Tera Project SLOKT12026T , and Institutional Research grant IUT20-13 for the support. Partial support for this work was obtained from the Israel Committee of High Education and the Israeli Prime Ministry office in the framework on the INREP consortium. Special thanks to Mr. David Swissa for his valuable contribution to the success of experimental measurements.

FundersFunder number
Israel Ministry of Science Technology and Space66032
European Commission
United States-Israel Binational Science Foundation2014083/2016
European Regional Development Fund2014-2020.4.01.15-0011, SLOKT12026T, 3.2.0101-0030, IUT20-13

    Keywords

    • EQCM
    • LiFePO
    • NaFePO
    • PVdF
    • QCM-D
    • composite electrode
    • in situ mechanical characterizations
    • lithium-ion battery
    • polymer binder
    • sodium-ion battery

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