Electrochemical strain microscopy time spectroscopy: Model and experiment on LiMn2O4

Abstract

Electrochemical Strain Microscopy (ESM) can provide useful information on ionic diffusion in solids at the local scale. In this work, a finite element model of ESM measurements was developed and applied to commercial lithium manganese (III,IV) oxide (LiMn 2 O 4 ) particles. ESM time spectroscopy was used, where a direct current (DC) voltage pulse locally disturbs the spatial distribution of mobile ions. After the pulse is off, the ions return to equilibrium at a rate which depends on the Li diffusivity in the material. At each stage, Li diffusivity is monitored by measuring the ESM response to a small alternative current (AC) voltage simultaneously applied to the tip. The model separates two different mechanisms, one linked to the response to DC bias and another one related to the AC excitation. It is argued that the second one is not diffusiondriven but is rather a contribution of the sum of several mechanisms with at least one depending on the lithium ion concentration explaining the relaxation process. With proper fitting of this decay, diffusion coefficients of lithium hosts could be extracted. Additionally, the effect of phase transition in LiMn 2 O 4 is taken into account, explaining some experimental observations. V C 2015 AIP Publishing LLC. [http://dx

Solid-state electrochemistry on the nanometer and atomic scales: the scanning probe microscopy approach

“…Practical implementation of ESM is significantly more complex, and utilizes a two-level detection scheme (a single-frequency ESM has also been widely utilized by the Kholkin group 66, 67 ). A slow (Hertz range) waveform is used to induce reversible electrochemical process in a solid (Fig.…”

Characterization of LiMn2O4 cathodes by electrochemical strain microscopy

“…5 At the same time, ESM experiments on commercial Li-ion battery electrodes comprising the particles of ionic conductors embedded in a polymer binder matrix represent non-trivial problem due to complex geometry of the samples 6 and consequent difficulties 7 resulting in less predictable contributions of different origin into the strain response. 8,9 From that point of view, we can generally talk about strain-based SPM (s-SPM) with a number of contributions, which must be separated in the experiments. 10 Understanding and separation of these contributions is an important step from purely qualitative to quantitative data interpretation and analysis.…”

“…On the other hand, high voltage may result in the appearance of additional contributions. 5,9,18 That is why we used ESM mapping with ramped AC voltage applied at each point to reveal how high AC voltage can influence the resulting signal. Figure 4 shows the spatial maps and extracted ESM amplitudes for both samples.…”

Simulation of Atomic Force Microscopy for investigating BaTiO3 and LiMn2O4 nanostructures based on Phase Field Approach

“…Next, we consider a diffusion-stress generation induced by electric field, see the current contribution [15]. For the description of intercalation compounds, the free energy per unit volume is defined as the sum of mechanical energy ψ mech , chemical energy ψ chem and electric energy ψ elec .…”

“…It simulates the deformation of the lithium manganese dioxide LiMn 2 O 4 (LMO) particle induced by the applied voltage and the evolution of lithium concentration after removing a DC pulse. The modeling results are compared to experimental data of ESM [15].…”