Rapid testing technology for internal deformation field of lithium ion battery structure

Abstract

The invention discloses a rapid testing technology for an internal deformation field of a lithium ion battery structure. According to the rapid testing technology for the internal deformation field ofthe lithium ion battery structure, firstly, an electrode sheet is obtained by coating a sizing agent on a positive and negative anode current collector; then, micron size internal marking points areadded to the surface of the electrode sheet after first coating is carried out; second coating of the sizing agent is carried out on the two surfaces of the electrode sheet, and then the prepared electrode sheet with the internal marking points is made into a lithium ion battery; then, by adjusting parameters of a CT imaging system, the exposure time of single projection is shortened as far as possible under the better voxel characteristic contrast of the internal marking points, and fast imaging is achieved; and combining a digital volume correlation internal deformation measurement method, the internal three-dimensional full-field displacement and full-field strain of the lithium ion battery are obtained. The rapid testing technology for the internal deformation field of the lithium ionbattery structure is used for solving the problem of in-situ rapid measurement of the internal deformation field of the lithium ion battery in different charging and discharging stages and in the multi-cycle cyclic process. Compared with the prior art, the exposure time of the single projection and the CT imaging time are shortened, and the radiation damage is greatly reduced.

Description

technical field [0001] The invention relates to a rapid testing technology for the internal deformation field of a lithium-ion battery structure, and belongs to the technical field of internal observation of materials and structures. Background technique [0002] The deformation of positive and negative electrode materials of traditional commercial lithium-ion batteries generally does not exceed 10% during charging and discharging, and the problems of structural failure and capacity fading are not very prominent. However, with the emergence of high-capacity alloy anode materials (such as silicon, germanium, tin, etc.) in recent years, the excessive volume deformation of such materials during the intercalation / delithiation process leads to structural failure and reversible capacity fading. Lithium-ion batteries composed of such materials are accompanied by outstanding electrochemical-force-thermal coupling behavior, whether it is at the microscopic electrode level, or at the ...

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Problems solved by technology

[0003] At present, there are no experimental reports on the measurement of the internal deformation field of real lithium-ion batteries, especially the lack of in-situ observation experimental technology for the internal deformation and damage behavior of lithium-ion batteries during multi-cycle cycles

Traditional single electrochemical or mechanical methods, as well as research on the particle level of electrode materials and half-cells, cannot well explain the internal deformation and structural failure of real full cells.

Existing techniques for characterizing material surface information, such as transmission electron microscopy, scanning electron microscopy, and optical technology, are powerless to obtain information about the internal deformation of real batteries.

Although the existing three-dimensional X-ray tomography (CT) method can obtain the internal morphology of the battery structure, most materials in lithium-ion batteries (such as separators, active materials, electrolytes, aluminum foil current collectors, etc.) are sensitive to X-rays. The absorption coefficient is small, and it takes a long time to scan and image using the existing small laboratory CT equipment, which generally takes more than half an hour (5-30μm resolution). For some nanometer resolution imaging, the scanning time even exceeds 20 hours. The battery produces serious radiation damage, which leads to chemical changes and morphology changes inside the battery, resulting in poor image quality and large errors in internal deformation measurement using digital volume correlation (DVC), so it cannot meet the requirements of lithium-ion batteries during multi-cycle cycles. Multi-scan imaging and measurement of the real internal deformation field

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