Hanbat University Researchers Develop a Separator to Improve Lithium-Metal Battery Performance

Bikitaite-infused cellulose separator enhances lithium-ion transport, boosting the high-rate performance of NCM90 while stabilizing the lithium-metal anode

CHUNGCHEONG PROVINCE, South Korea, Sept. 14, 2026 /PRNewswire/ -- Lithium-metal batteries paired with high-nickel cathodes, such as NCM90, offer high energy density, but rapid cycling typically triggers anode dendrite growth, electrolyte degradation, and short circuits. While separator engineering is traditionally used to stabilize the lithium-metal anode, researchers discovered that modifying the separator also substantially improves high-rate performance at the cathode.

To achieve this, researchers led by Professor Sun-Yul Ryou at the Department of Chemical and Biological Engineering, Hanbat National University, Republic of Korea, developed a cellulose-based separator infused with bikitaite zeolite, called CBT. The separator combines the porous structure of cellulose with the ion-transport properties of bikitaite, forming interconnected pathways for lithium-ion movement.

This paper was made available online on May 28, 2026, and was published in Volume 36, Issue 54 of the journal Advanced Functional Materials on July 6, 2026. 

The CBT separator exhibited an ionic conductivity of 3.45 × 10⁻³ S cm⁻¹ and a lithium-ion transference number of 0.742. These properties enabled rapid and more uniform lithium-ion transport through the separator, reducing polarization and facilitating electrochemical reactions under demanding high-rate conditions.

"Our results show that battery performance can be improved not only through new cathode and anode materials, but also through separator engineering. What was particularly interesting was that the effect of the modified separator extended beyond the lithium-metal anode and significantly improved the high-rate performance of the NCM90 cathode," explains Prof. Ryou.

This effect became increasingly evident as the discharge rate increased. At 1C, cells with the CBT and conventional polyethylene separators both delivered approximately 197 mAh g⁻¹. At 2C, the capacities were 187 and 165 mAh g⁻¹, respectively. At 4C, the difference widened substantially: the NCM90 cathode delivered 163 mAh g⁻¹ with CBT compared to 115 mAh g⁻¹ with the conventional separator, corresponding to an improvement of approximately 42%.

At the same time, the separator retained the benefits traditionally sought from separator engineering on the lithium-metal side. Real-time observation of lithium deposition showed no visible dendrite growth in cells equipped with CBT. Instead, lithium formed a smoother, more compact layer and was removed more uniformly during stripping.

The CBT separator delivered strong long-term stability in high-rate Li||NCM90 cells. It retained roughly 60% capacity after 2,500 cycles at 2C/4C, around 68.9% after 150 cold cycles at −25 °C, and held up at 200 °C. Unlike costly electrode redesigns, separator modifications integrate easily into existing production lines. This makes it a practical way to improve performance without changing cell chemistry, though testing in commercial pouch or cylindrical formats is still needed.

"Functional separators should not be viewed only as barriers that separate the two electrodes or as a means of protecting the lithium-metal anode. By controlling ion transport across the cell, they could become an important design element for simultaneously achieving high energy density and high-rate operation in next-generation batteries," concludes Prof. Ryou.

Reference
Title of original paper: Fast Charge–Discharge of LiNi_0.9Co_0.05Mn_0.05 Enabled by a Bikitaite-Infused Separator for Li Metal Batteries
Journal: Advanced Functional Materials
DOI: https://doi.org/10.1002/adfm.75036 

About Hanbat National University (HBNU) 
Founded in 1927 and based in Daejeon, South Korea, HBNU is a public institution renowned for its engineering programs and strong industry–academia collaboration.
https://www.hanbat.ac.kr/eng/ 

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SOURCE Hanbat National University