16 February 2026 — Modern lithium-ion batteries use graphite as the material in the anode. To improve performance, graphite particles are coated with a very thin layer of carbon. This process presents several challenges.
Modern lithium-ion batteries use graphite as the material in the anode. To improve performance, graphite particles are coated with a very thin layer of carbon. This process presents several challenges. The coating must be extremely uniform, and the material must be heated very slowly — no more than 10°C per minute — during the coating phase. If heated too quickly, the coating can crack, bubble, or peel, ultimately degrading battery performance.
Researchers from the Ukrainian Gas Institute have designed and tested a special heating container, known as a saggar, to carefully process graphite powder used for lithium-ion battery anodes. The system ensures that heating remains slow, uniform, and precisely controlled.
The saggar proved effective for this task. It is a thick-walled ceramic container used in high-temperature processing that helps distribute heat evenly while protecting the material inside from contamination and direct flame exposure.
The article “Thermal Engineering Calculation of Saggar for Graphite Powder Processing with Nanoscale Coating of Carbonized Pitch as Li-ion Battery Anode,” published in Nanosystems, Nanomaterials, Nanotechnologies, presents a method of convective heating using flue gases from natural gas combustion. The authors performed detailed thermal engineering calculations and numerical modeling using COMSOL Multiphysics to analyze the complex heat transfer process — from the gas flow to the saggar wall, through the wall, and into the powder layer.
The findings show that gradual heating over a period of up to 12 hours maintains a safe heating rate that does not exceed the critical threshold of 10°C per minute. The validated thermal calculations for the 1-liter saggar provide a foundation for scaling up the design to an industrial saggar with a volume of 40 liters.
