Electrochemical capacitors, often called supercapacitors, are the sprinters of the energy world. They charge instantly and deliver massive bursts of power on demand. The trade-off, however, is their lack of endurance: they cannot store much total energy, and they tend to leak their charge quickly when sitting idle. While engineers know that cranking up the operating voltage could solve the energy density problem, doing so almost always causes the internal chemical bath (the electrolyte) to break down and fail.
To bypass this voltage trap, a joint research effort detailed in Carbon Research introduces an ingenious "co-design" strategy. By building a custom electrode out of organic plant matter and pairing it with a highly specialized fluid, the team successfully stabilized a supercapacitor operating at a remarkable 4.0 volts.
This structural and chemical triumph is the result of a close partnership led by Dr. Feng Gong at Southeast University and Dr. Hualin Ye from Nanjing Normal University. By combining the deep resources of the Key Laboratory of Energy Thermal Conversion and Control (Ministry of Education) and the Jiangsu Key Laboratory of New Power Batteries, the researchers tackled the supercapacitor's core flaws from the inside out.
Instead of treating the solid hardware and the liquid chemicals as completely separate components, the research team engineered them to fit together like a lock and key. They began by transforming lignin, an abundant natural polymer found in plant cell walls, into a highly porous carbon electrode. These carbon structures feature incredibly tight, sub-nanometer holes.
To complement this, the scientists formulated a weakly solvating lithium-based electrolyte mixed with a specific fluorinated diluent.
The mechanism behind their success is twofold. First, the tiny pores in the lignin-derived carbon are geometrically perfectly matched to catch and hold the specific solvated lithium ions, generating massive energy storage capacity. Second, the fluorinated liquid acts as a chemical bodyguard. It actively suppresses degradation and blocks parasitic reactions, keeping the entire system stable even under the intense electrical pressure of a 4.0 V charge.
Performance Milestones Reached:
- Shattering the Ceiling: The device operates smoothly at an unprecedented 4.0 V, avoiding the rapid self-discharge that plagues standard models.
- High Energy Density: By maximizing the fit between the ions and the carbon pores, the system achieves an impressive 77.4 Wh kg⁻¹, blurring the line between fast-charging supercapacitors and traditional batteries.
- Marathon Endurance: The protective chemistry ensures exceptional durability. After enduring 10,000 rigorous charge and discharge cycles, the capacitor maintained over 90% of its original capacity.
As industries scramble to find better ways to power energy-intensive technologies, from heavy-duty electric transit to smart power grids, this breakthrough offers a highly practical blueprint. The collaborative work out of Southeast University and Nanjing Normal University proves that with the right combination of bio-based materials and clever chemistry, we no longer have to choose between quick power and long-lasting energy.
Corresponding Authors:
Feng Gong Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University, Nanjing, Jiangsu, China.
Hualin Ye Jiangsu Key Laboratory of New Power Batteries, Jiangsu Collaborative Innovation Center of Biomedical Functional Materials, School of Chemistry and Materials Science, Nanjing Normal University, Nanjing, China.
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Journal reference: Zhang, S., Liu, S., Si, S. et al. Lignin-derived hierarchical porous carbons enabling high-voltage electrochemical capacitors with low self-discharge. Carbon Res. 5, 11 (2026).
https://doi.org/10.1007/s44246-025-00255-z
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About Carbon Research
The journal Carbon Research is an international multidisciplinary platform for communicating advances in fundamental and applied research on natural and engineered carbonaceous materials that are associated with ecological and environmental functions, energy generation, and global change. It is a fully Open Access (OA) journal and the Article Publishing Charges (APC) are waived until Dec 31, 2025. It is dedicated to serving as an innovative, efficient and professional platform for researchers in the field of carbon functions around the world to deliver findings from this rapidly expanding field of science. The journal is currently indexed by Scopus and Ei Compendex, and as of June 2025, the dynamic CiteScore value is 15.4.
