Quantification and modeling of mechanical degradation in lithium-ion batteries based on nanoscale imaging

Vanessa Wood,Vincent De Andrade,Paul Baade,Ben-Elias Brandt,Simon Müller,Patrick Pietsch,Francesco De Carlo

doi:10.1038/s41467-018-04477-1

Vanessa Wood, Vincent De Andrade + Show 5 more

Open Access

https://doi.org/10.1038/s41467-018-04477-1

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Journal: Nature Communications	Publication Date: Jun 14, 2018
Citations: 109	License type: open-access

Affiliation: ETH Zurich, Argonne National Laboratory

Abstract

Capacity fade in lithium-ion battery electrodes can result from a degradation mechanism in which the carbon black-binder network detaches from the active material. Here we present two approaches to visualize and quantify this detachment and use the experimental results to develop and validate a model that considers how the active particle size, the viscoelastic parameters of the composite electrode, the adhesion between the active particle and the carbon black-binder domain, and the solid electrolyte interphase growth rate impact detachment and capacity fade. Using carbon-silicon composite electrodes as a model system, we demonstrate X-ray nano-tomography and backscatter scanning electron microscopy with sufficient resolution and contrast to segment the pore space, active particles, and carbon black-binder domain and quantify delamination as a function of cycle number. The validated model is further used to discuss how detachment and capacity fade in high-capacity materials can be minimized through materials engineering.

Highlights

Capacity fade in lithium-ion battery electrodes can result from a degradation mechanism in which the carbon black-binder network detaches from the active material
In lithium-ion batteries (LIBs) electrodes, micrometer-sized electrochemically active particles are mechanically stabilized by a polymeric binder
Few studies have successfully imaged the carbon blackbinder domain and, to the best of our knowledge, none have shown its detachment from the active particles

Summary

Introduction

Capacity fade in lithium-ion battery electrodes can result from a degradation mechanism in which the carbon black-binder network detaches from the active material. Many high-capacity materials undergo volumetric expansion and contraction or mechanical changes such as fracture during cycling, which can lead to detachment of the active particles from the carbon black-binder network. This is an effect that occurs both in highvoltage cathode materials, such as LiMn2O4, which rupture during cycling[9], and in high-capacity anode materials such as silicon that undergo alloying reactions with lithium and large volumetric changes (280% in the case of silicon) upon (de)lithiation[10,11,12]. To achieve the goal of mitigating the severe degradation that occurs in pure silicon electrodes, the silicon is embedded into mechanical robust graphite, which undergoes small volumetric changes on the order of 10% upon (de)lithiation[16] and exhibits excellent cycling stability under normal operating conditions[17,18]

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