Electrochemical stiffness in lithium-ion batteries

Abstract

Although lithium-ion batteries are ubiquitous in portable electronics, increased charge rate and discharge power are required for more demanding applications such as electric vehicles. The high-rate exchange of lithium ions required for more power and faster charging generates significant stresses and strains in the electrodes that ultimately lead to performance degradation. To date, electrochemically induced stresses and strains in battery electrodes have been studied only individually. Here, a new technique is developed to probe the chemomechanical response of electrodes by calculating the electrochemical stiffness via coordinated in situ stress and strain measurements. We show that dramatic changes in electrochemical stiffness occur due to the formation of different graphite-lithium intercalation compounds during cycling. Our analysis reveals that stress scales proportionally with the lithiation/delithiation rate and strain scales proportionally with capacity (and inversely with rate). Electrochemical stiffness measurements provide new insights into the origin of rate-dependent chemomechanical degradation and the evaluation of advanced battery electrodes.

In situ and Operando Tracking of Microstructure and Volume Evolution of Silicon Electrodes by using Synchrotron X‐ray Imaging

“…Consecutive accumulation of strain and stress on other battery components is induced, which apparently has a negative impact on maintaining the microstructure integrity of silicon particles as well as the reversibility of the structural changes of thesilicon electrode in the long term. [24] During subsequent delithiation, which is shown in the second row in Figure 2b,t he fragmented granules tend to recover back to the previous particles hape. The cracks between the granules disappear stepwise with lithium being extracted from Li x Si accompanied by ad ecrease in transmission.…”

“…Furthermore, fracture of particles significantly contributes to the volume expansion of the electrode not only laterally within the electrode plane but also in the longitudinal direction (i.e., perpendicular to the plane shown in Figure b). Consecutive accumulation of strain and stress on other battery components is induced, which apparently has a negative impact on maintaining the microstructure integrity of silicon particles as well as the reversibility of the structural changes of the silicon electrode in the long term …”

“…The cracks between the granules disappear stepwise with lithium being extracted from Li x Si accompanied by a decrease in transmission. The recovery/shrinkage of a particle can be attributed to the release of accumulated strain and stress during lithiation caused by particle expansion . Eventually the particles transform roughly to their original shape but still exhibit a few visible fractures.…”

Influence of Atmosphere on Electrochemical Performance of LiNi0.8Co0.1Mn0.1O2 Electrodes for Li-Ion Batteries

“…[1][2][3][4][5] However, the energy density of the LIBs is mainly controlled by the electrode materials, especially the cathode materials. [6] Among a large number of cathode candidates, LiCoO 2 has been widely used as a commercialized cathode material for LIBs due to its good cycling properties and excellent rate capability.…”

Strain Coupling of Conversion‐type Fe3O4 Thin Films for Lithium Ion Batteries

“…[1] Foralloying and conversion reactions, the volume expansion is more severe than that occurs during an intercalation reaction, [2] and previous reports have shown that excessive volumetric changes result in pulverization of the initial electrode materials,disconnection of active materials from the binder and current collector,and damage of the established solid-electrolyte interface layer. [1] Foralloying and conversion reactions, the volume expansion is more severe than that occurs during an intercalation reaction, [2] and previous reports have shown that excessive volumetric changes result in pulverization of the initial electrode materials,disconnection of active materials from the binder and current collector,and damage of the established solid-electrolyte interface layer.…”