Dual-design carbon catalyst helps lithium–oxygen batteries deliver high capacity with lower energy loss

Lithium–oxygen batteries are widely considered a promising candidate for next-generation energy storage because of their exceptionally high theoretical energy density. However, their development has been limited by poor cycling stability, slow charging reactions, and substantial energy loss.

Researchers from the Beijing Institute of Technology and Beijing Wuzi University have now developed a metal-free, nitrogen-doped porous carbon catalyst that simultaneously improves oxygen transport and electrochemical reaction kinetics. The optimized lithium–oxygen battery achieved a specific capacity of approximately 21,395 mAh g⁻¹ and operated for more than 2,500 hours under controlled cycling conditions.

The findings were published in Sustainable Carbon Materials.

“Our results show that high capacity and low charging polarization do not necessarily have to be competing goals,” said corresponding author Ying Yao. “By regulating both the pore structure and the chemical configuration of active nitrogen sites, we created a carbon cathode that can better accommodate discharge products while also promoting their efficient decomposition.”

Why lithium–oxygen batteries lose performance

Lithium–oxygen batteries generate electricity through reactions involving lithium ions and oxygen. During discharge, these reactions produce lithium peroxide, or Li₂O₂.

Because Li₂O₂ is electrically insulating and difficult to dissolve, it gradually accumulates on the cathode. The material can block pores, cover catalytic surfaces, and restrict the movement of oxygen and lithium ions. It also becomes difficult to decompose during charging, leading to higher charging voltages and reduced energy efficiency.

The morphology of Li₂O₂ presents an additional challenge. Large toroidal particles can support high discharge capacity because they store substantial amounts of reaction product. However, they usually have poor electrical contact with the electrode and require high charging voltages. Flower-like or film-like products are generally easier to decompose, but they can rapidly cover the electrode surface and limit capacity.

This creates a persistent trade-off between battery capacity and charging polarization.

Controlling pores and active sites together

To address this problem, the researchers prepared carbon catalysts from a zeolitic imidazolate framework known as ZIF-7. They combined solvent-mediated precursor control with vacuum-assisted heat treatment, producing carbon materials with different pore structures and nitrogen configurations.

The most effective material, called ZDC, contained interconnected pores spanning approximately 3 to 30 nanometers, including larger mesopores that provided pathways for oxygen and lithium-ion transport. Its surface also contained a high proportion of pyridinic nitrogen, an active nitrogen configuration that promotes oxygen reactions and assists the decomposition of Li₂O₂ during charging.

The researchers found that the two features performed complementary functions. Large pores primarily improved mass transport and prevented pore blockage, while pyridinic nitrogen sites accelerated charge transfer and reduced the energy barrier for Li₂O₂ decomposition.

High capacity without severe charging polarization

The optimized ZDC cathode delivered a specific discharge capacity of approximately 21,395 mAh g⁻¹ at 100 mA g⁻¹, considerably higher than the other tested materials. It also achieved a low charge overpotential of approximately 0.77 volts and maintained cycling for more than 2,500 hours at a fixed capacity of 500 mAh g⁻¹.

Notably, the cathode promoted the formation of toroidal Li₂O₂, a morphology normally associated with high capacity but difficult charging. Despite this, the battery showed lower charging polarization than a comparison cathode containing flower-like Li₂O₂.

Electrochemical and microscopic analyses indicated that the accessible pyridinic nitrogen sites enabled efficient decomposition of the toroidal products, while the hierarchical pore network preserved transport pathways throughout cycling.

A broader framework for battery catalyst design

The study provides a materials design strategy that goes beyond optimizing a single catalytic property. Instead, it demonstrates the importance of coordinating pore-level transport, active-site accessibility, and surface chemistry.

According to the researchers, this dual-modulation approach could guide the development of other porous carbon electrodes in which solid reaction products progressively reshape transport pathways and catalytic interfaces during operation.

The results offer a promising route toward lithium–oxygen batteries that combine high energy storage capacity, improved charging efficiency, and longer operating life.

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Journal reference: Hu X, Wang M, Yang F, Gou Z, Chen Z, et al. 2026. Breaking the capacity-polarization trade-off in Li–O₂ batteries through dual-modulation of hierarchical porosity and active site configurations in ZIF-derived electrocatalysts. Sustainable Carbon Materials 2: e021 doi: 10.48130/scm-0026-0016  

https://www.maxapress.com/article/doi/10.48130/scm-0026-0016

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About Sustainable Carbon Materials:

Sustainable Carbon Materials (e-ISSN 3070-3557) is a multidisciplinary platform for communicating advances in fundamental and applied research on carbon-based materials. It is dedicated to serving as an innovative, efficient and professional platform for researchers in the field of carbon materials around the world to deliver findings from this rapidly expanding field of science. It is a peer-reviewed, open-access journal that publishes review, original research, invited review, rapid report, perspective, commentary and correspondence papers.

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