Thick Electrode Boosts Battery Power by 75%

Abstract

Thick electrodes are essential for achieving high-energy-density lithium-ion batteries, yet their performance is often constrained by transport limitations. A central factor is the carbon-binder domain (CBD), which plays a dual role in electrode. It provides electronic pathways but simultaneously impedes ionic transport. The coexistence of pores between active materials and nanoscale pores within the CBD has previously been recognized, but their individual contributions have not been quantitatively resolved. Here, we introduce the Dual-Pore Transmission Line Model (DTLM), which separates ionic transport into two parallel pathways through interparticle and CBD pores. DTLM provides a physically grounded and domain-resolved interpretation of porosity-tortuosity behavior, offering additional insight beyond what can be obtained from conventional Bruggeman relations or transmission line models. Guided by this framework, we design an optimized electrode formulation with 2 wt.% carbon black (CB), moderate milling, and a reduced binder-to-CB ratio. This formulation maintains CBD pore accessibility, reduces both electronic and ionic resistance, and substantially improves rate capability in high-loading (10.0 mAh cm−2) and low-porosity (20%) electrodes. Beyond this demonstration, DTLM offers a transferable framework for microstructure-guided design of next-generation thick electrodes and delivers quantitative insight into how electronic and ionic transport are balanced within multiscale pore networks.

A research team, affiliated with UNIST has unveiled a new type of thick electrode aimed at solving a common challenge in battery design. That is as the capacity increases, power often decreases. This breakthrough could enable electric vehicles (EVs) to travel farther on a single charge without sacrificing acceleration or responsiveness.

Led by Professor Kyeong-Min Jeong from the School of Energy and Chemical Engineering, the team optimized the internal pore structure of thick electrodes, achieving a 75% increase in power output compared to conventional designs.

In the EV market, extending driving range is a key goal. One way to do this is by stacking more active material within the electrode, creating a thicker structure. However, thicker electrodes typically deliver less power because Li-ions need to travel longer distances, and the complex pore network can slow down the discharge process.

The new electrode maintains a high capacity of 10 mAh/cm² while significantly enhancing power performance. Specifically, under a high 2C discharge rate, traditional electrodes deliver about 0.98 mAh/cm², whereas the new design reaches 1.71 mAh/cm²-roughly 75% more energy in a short burst.

This improvement stems from a detailed analysis of the electrode's internal pore structure. In this study, the team identified two types of pores. Large ones between particles that help Li-ions flow easily, and tiny pores formed by conductive additives and binders, known as the carbon-binder domain (CBD). They discovered that these micro-pores can hinder ion flow. To better understand this, they developed a new model, called the Dual-Pore Transmission Line Model (DTLM), which separates ionic pathways into two parallel channels. Using DTLM, they further optimized manufacturing processes and material ratios to fine-tune the internal pore structure for improved performance.

"Having a quantitative way to analyze these structures provides a solid foundation for applying advanced AI techniques, like physics-informed neural networks, to battery design-even when data is limited," said first author Byeong-Jin Jeon.

Professor Jeong added, "As we move toward thicker electrodes, it is not just about the materials themselves, but also how we design and manipulate their microstructures." He further added, "Our work offers valuable insights not only for high-nickel batteries but also for other next-generation chemistries, like lithium iron phosphate (LFP), where controlling the internal structure is particularly important."

The findings of this research have been published in the December 2025 issue of Advanced Energy Materials, a leading journal in energy and environmental science. The study was supported by the Ministry of Trade, Industry and Energy (MOTIE) through KITECH, as part of a project to develop large-scale manufacturing equipment for dry electrodes in batteries.

Journal Reference

Byeong-Jin Jeon, Hyeon Jeong, Suhui Yoon, et al., "Thick Electrode Design Enabled by a Carbon-Binder Domain-Resolved Dual-Pore Transmission Line Model for Lithium-Ion Batteries," Adv. Energy Mater., (2025).