Effect of thickness on the maximum potential drop of current collectors

Abstract: The basic principle for achieving high-power capability on an electrochemical energy storage cell is minimizing the overall resistance. The resistance due to current collecting systems has not received sufficient attention in the past, presumably because it was not considered of significance for low-power batteries and supercapacitors. However, the necessity of high-power cells has reduced other sources of the inner resistance, and the current collector potential drop has become more important. Moreover, the miniaturization of energy storage devices could increase the ohmic loses in current collectors. In this work, we have developed an electrical model to assess the effect of the current collector thickness on the maximum potential drop. We have found that the thickness of current collectors is a critical parameter that can increase the maximum potential drop drastically. Indeed, the maximum potential drop of current collectors remains almost constant for thicknesses greater than 500 lm, but below this value, there is an inverse relationship between the maximum potential drop and the thickness. We have also analyzed the effect of the material and tab position in the maximum potential drop.

• The paper finds that reducing current collector thickness from 500 μm to 10 μm can increase the maximum potential drop by up to 50 times.
• The researchers developed a COMSOL Multiphysics model to analyze potential distribution in copper and aluminum collectors under various geometries.
• The study highlights that asymmetric tab placement raises potential drop by approximately 14% and that aluminum’s higher resistivity results in about 60% greater losses than copper.

Effect of Thickness on the Maximum Potential Drop of Current Collectors

This paper presents an in-depth examination of the impact of current collector thickness on the maximum potential drop in electrochemical energy storage devices, such as lithium-ion batteries (LIBs) and supercapacitors. In the context of miniaturizing electronic devices and the growing demand for thin and flexible energy storage solutions, this study addresses a critical, albeit often overlooked, component of these devices: the current collectors.

The researchers developed an electrical model employing COMSOL Multiphysics to determine the electrical potential in various geometries of thin metallic sheets. This investigation specifically focuses on copper (Cu) and aluminum (Al) current collectors, common in LIC pouch cells with specific thickness configurations. The paper outlines that while resistance from current collectors has traditionally been neglected in low-power applications, it becomes significant in high-power and miniaturized cells where other resistive elements are minimized.

The study reveals critical insights about the relationship between thickness and maximum potential drop. It highlights a prominent inverse relationship between potential drop and thickness below a critical dimension of 500 μm. Above this threshold, potential drop remains relatively constant. Thus, the findings indicate that when designing ultra-thin energy storage solutions, careful consideration of collector thickness is paramount due to its pronounced effect on ohmic losses.

An analytical exploration was also conducted regarding the role of the positioning of the collecting tab. The paper notes that an asymmetrical tab placement results in a slight increase of about 14% in the maximum potential drop compared to a symmetrical layout, emphasizing the importance of design considerations in order optimization.

Numerical results revealed that reducing thickness to 10 μm from 500 μm potentially increases the maximum potential drop by a factor of 50, confirming the pressing need to balance thickness reduction against other system parameters. Contrasting Al’s greater resistivity compared to Cu's results in a higher potential drop by approximately 60%, yet the trend concerning thickness remains universally applicable across materials.

The practical implications of this research hold significant value for the design and prototype development of next-generation electrochemical energy cells. Thinner current collectors achieve advancements in energy density and cost-efficiency; however, they introduce challenges such as increased internal resistance and potential thermal management issues. The paper advocates for a nuanced approach in balancing these parameters to avoid detrimental mechanical deformations or overheating.

In conclusion, the findings underscore the importance of current collector architecture in enhancing the performance of energy storage cells. As the industry shifts towards ultra-thin, flexible devices, understanding these detailed technical relationships is crucial for further advancements in portable and wearable electronics. Future research should continue to explore optimizations in current collector design, contributing to the development of high-performance, cost-effective energy solutions.