Test for Collector-Active Material Bonding Strength in Lithium-Ion Electrodes Ensuring Battery Performance

Lithium-ion batteries are ubiquitous in portable electronics and are increasingly being explored for electric vehicles and large-scale energy storage. While the overall function of these batteries is well understood, the internal structure and its impact on performance are less familiar. This report focuses on a critical aspect of electrode design: the bonding strength between the current collector and the active material.

A lithium-ion battery electrode consists of a current collector (aluminum for the positive electrode and copper for the negative) coated with a layer containing the active material and a binder. During charge and discharge cycles, lithium ions move between the electrodes. This process can cause the active material to expand and contract, potentially leading to separation from the current collector. Weak bonding at this interface increases electrical resistance and reduces battery lifespan. Therefore, ensuring a strong bond between the collector and active material is essential for optimal battery performance.

Methods for evaluating the bonding strength between the collector and active material in a lithium-ion battery electrode include utilizing a standard tensile tester to carry out a peel test. In this study, a Labthink C610H Tensile Tester was used.

First prepare a sample, a rectangular electrode strip (1.9 cm wide) is secured to a stainless-steel plate using double-sided adhesive tape. One end of the electrode strip is peeled from the steel plate. The peeled end and the opposite end are clamped into the upper and lower grips of the tensile tester, respectively. The test is automated and performed at a constant peel rate of 10 mm/minute. The force required to separate the collector and active material is continuously measured. Upon test completion, the instrument automatically displays the force data, which can be used to assess the bonding strength between the two materials.

The peel test described here simulates the shear stress experienced by the collector-active material interface during battery operation. The force data obtained reflects the strength of the bond between these two components. A higher force indicates a stronger bond, signifying better resistance to delamination and improved battery performance.

A peel test utilizing a tensile tester is a straightforward and effective method for evaluating the bonding strength between the current collector and active material in lithium-ion battery electrodes. The peel test provides valuable insights into the mechanical integrity of the electrode structure, aiding in the development of batteries with longer lifespans and improved performance.


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