Three-Dimensional Mapping of Resistivity and Microstructure of Composite Electrodes for Lithium-Ion Batteries

Abstract

Nanoparticle silicon−graphite composite electrodes are a viable way to advance the cycle life and energy density of lithium-ion batteries. However, characterization of composite electrode architectures is complicated by the heterogeneous mixture of electrode components and nanoscale diameter of particles, which falls beneath the lateral and depth resolution of most laboratory-based instruments. In this work, we report an original laboratory-based scanning probe microscopy approach to investigate composite electrode microstructures with nanometerscale resolution via contrast in the electronic properties of electrode components. Applying this technique to silicon-based composite anodes demonstrates that graphite, SiO x nanoparticles, carbon black, and LiPAA binder are all readily distinguished by their intrinsic electronic properties, with measured electronic resistivity closely matching their known material properties. Resolution is demonstrated by identification of individual nanoparticles as small as ∼20 nm. This technique presents future utility in multiscale characterization to better understand particle dispersion, localized lithiation, and degradation processes in composite electrodes for lithium-ion batteries.

Guiding the Design of Heterogeneous Electrode Microstructures for Li‐Ion Batteries: Microscopic Imaging, Predictive Modeling, and Machine Learning

“…Finally, for exploring the spatial electrical properties of electrode materials, scanning spreading resistance microscopy (SSRM) has been applied to measure the resistivity of surface layers on electrodes in 3D with spatial resolution of nanometers for fields of view of 10s of micrometers (Figure 3) [43,44] and holds great potential for understanding the influence of different operating conditions, formation conditions, electrolyte additives, and electrode materials on the thickness and electrical resistivity of surface layers on electrodes, thus providing valuable impedance information for modeling techniques. These heterogeneities at the electrode and particle scales incur consequences for the operation of cells and must be reflected in modeling methods to achieve a high degree of accuracy and be able to predict degradation and optimal operating conditions.…”

Characterizing Batteries by In Situ Electrochemical Atomic Force Microscopy: A Critical Review

“…[ 39 ] Closely related techniques have utilized various input/detection arrangements to provide high‐resolution contrast in the electronic properties (resistivity mapping) of electrode components which, for example, can enable different materials to be distinguished. [ 40 ]…”

Towards a 3D-resolved model of Si/Graphite composite electrodes from manufacturing simulations

“…These changes result in electrode thickness variations [14], loss of electrical particle contact within the microstructure [15,16], continued consumption of electrolyte [17], all of which affects the electrode's electrochemical performance [18]. All those phenomena depend on the exact particles location along the electrode, where the heterogeneous distribution of electrode components in 3D becomes important when trying to understand the coupled mechanical and electrochemical behavior of graphite/Si composite electrodes [19,20]. Experimental 3D probing techniques, such as X-ray tomography [19], or the more recently developed scanning spreading resistance microscopy (SSRC) [20], are critical when trying to extract fundamental insights about the microstructure-performance relationships of battery electrodes in general, and of graphite/Si composite in particular.…”

“…All those phenomena depend on the exact particles location along the electrode, where the heterogeneous distribution of electrode components in 3D becomes important when trying to understand the coupled mechanical and electrochemical behavior of graphite/Si composite electrodes [19,20]. Experimental 3D probing techniques, such as X-ray tomography [19], or the more recently developed scanning spreading resistance microscopy (SSRC) [20], are critical when trying to extract fundamental insights about the microstructure-performance relationships of battery electrodes in general, and of graphite/Si composite in particular. However, those techniques are too costly to be used systematically, and often require not routinely accessible instrumentations, such as synchrotron beamlines.…”

“…However, those techniques are too costly to be used systematically, and often require not routinely accessible instrumentations, such as synchrotron beamlines. In addition, those techniques often need to find compromises between the appropriate resolution/phase contrast needed to resolve certain phases, such as the carbon binder domain (CBD) [21,22], and the sample size, which can hinder microstructural representativity [20].…”