Korea Research Institute of Chemical Technology develops dry-electrode technology that dramatically reduces lithium-ion transport resistance

The additive and completed electrode developed by the research team. [Korea Research Institute of Chemical Technology]
The additive and completed electrode developed by the research team. [Korea Research Institute of Chemical Technology]

South Korean researchers have solved the so-called "lithium traffic jam" problem that degrades electric vehicle battery performance — using just 0.5% of an additive.

The Korea Research Institute of Chemical Technology announced Tuesday that a research team led by Moon San and Seok Jeong-don developed a dry thick-film cathode technology that dramatically reduces lithium-ion transport resistance by using graphitic carbon nitride (g-C3N4) as a cathode additive.

To increase a battery's energy density, the electrode must be made thicker to hold more active material for energy storage. However, as the electrode grows thicker, lithium ions struggle to move freely through its interior, making it harder to fully utilize the stored energy.

Conventional wet-electrode manufacturing mixes cathode materials and binders in a solvent before coating and drying, a process that causes uneven internal composition. Dry-process methods, which eliminate the solvent and drying steps, had also failed to address the lithium-ion transport resistance that arises in thick electrodes.

The research team used porous graphitic carbon nitride as a "guide" to facilitate lithium-ion movement. Nitrogen atoms on the additive's surface temporarily bind to lithium ions and then release them, promoting the transfer of lithium ions from the electrolyte to the cathode material.

From left: Senior Researcher Seok Jeong-don, postdoctoral researcher Park Jin-gyu, student researcher Lee Ga-ram and Senior Researcher Moon San. [Korea Research Institute of Chemical Technology]
From left: Senior Researcher Seok Jeong-don, postdoctoral researcher Park Jin-gyu, student researcher Lee Ga-ram and Senior Researcher Moon San. [Korea Research Institute of Chemical Technology]

The technique reduced the activation energy required for lithium-ion transport by about 56 percent, from 49.8 kJ/mol to 22.1 kJ/mol. The porous structure also allows the electrolyte to permeate evenly into the electrode's interior, further improving ion mobility.

In testing, a dry electrode roughly 68 micrometers thick with 0.5 percent additive showed a capacity increase of 165.9 percent under 3C high-rate discharge conditions, rising from 58.8 mAh/g to 156.2 mAh/g. Power density improved by up to 2.85 times.

In a pouch-type full cell, capacity retention after 600 charge-discharge cycles improved from 72.9 percent to 81.3 percent.

The research team also found that adding too much of the additive has the opposite effect — electrical resistance increases and the electrode swells again, impeding ion movement. This means not only the amount of additive but also its placement within the electrode and the pore structure must be optimized.

The technology is expected to cut battery production costs and energy consumption, as it applies to a dry manufacturing process that requires no solvent drying or recovery steps. However, actual mass production yields and the extent of manufacturing cost reductions will require further verification.

"The significance lies in simultaneously improving electrolyte wettability and ion transport with just 0.5 percent additive, while optimizing not only the amount of additive but also its placement and electrode structure," said Moon San, director of the Secondary Battery Research Center at the Korea Research Institute of Chemical Technology.

The findings were published as the cover article in the August issue of the international journal Exploration.


nbgkoo@heraldcorp.com