Key Takeaways & Executive Findings
- •• A defect-rich porous carbon framework (DRPCF) with N/O co-doping was synthesized using porous g-C3N4 and dopamine, achieving a high specific surface area and abundant active defect sites. • The optimized DRPCF-2/1-700 anode exhibited exceptional sodium storage capacity of 328.2 mAh g−1 after 900 cycles at 1 A g−1 and potassium storage capacity of 321.5 mAh g−1 after 1200 cycles at 1 A g−1. • The superior performance is attributed to pseudocapacitive storage and the reversible filling/removal of Na+ and K+ in electrochemically active defects, as confirmed by ex-situ Raman spectroscopy. • The rate capability and cycling stability of DRPCF-2/1-700 outperform most reported carbon materials, highlighting its potential for advanced sodium and potassium-ion batteries.
Abstract
Carbon with its high electrical conductivity, excellent chemical stability, and structure ability is the most promising anode material for sodium and potassium ion batteries. We developed a defect-rich porous carbon framework (DRPCF) built with N/O-co-doped mesoporous nanosheets and containing many defects using porous g-C3N4 (PCN) and dopamine (DA) as raw materials. We prepared samples with PCN/DA mass ratios of 1/1, 2/1 and 3/1 and found that the one with a mass ratio of 2/1 and a carbonization temperature of 700 °C in an Ar atmosphere (DRPCF-2/1-700), had a large specific surface area with an enormous pore volume and a large number of N/O heteroatom active defect sites. Because of this, it had the best pseudocapacitive sodium and potassium ion storage performance. A half battery of Na//DRPCF-2/1-700 maintained a capacity of 328.2 mAh g−1 after being cycled at 1 A g−1 for 900 cycles, and a half battery of K//DRPC-2/1-700 maintained a capacity of 321.5 mAh g−1 after being cycled at 1 A g−1 for 1200 cycles. The rate capability and cycling stability achieved by DRPCF-2/1-700 outperforms most reported carbon materials. Finally, ex-situ Raman spectroscopy analysis result confirms that the filling and removing of K+ and Na+ from the electrochemically active defects are responsible for the high capacity, superior rate and cycling performance of the DRPCF-2/1-700 sample.
1. Introduction
In the past 30 years, lithium-ion batteries (LIBs) have dominated the primary market of portable power sources due to their high energy density. However, the price of LIBs keeps increasing with the expansion of market to large-scale energy storage plants and electric vehicles. Therefore, sodium/potassium-ion batteries (SIBs/PIBs) have attracted significant attention due to their potentially low production prices derived from the abundance of sodium and potassium. Unfortunately, the much larger radius of Na+ and K+ than that of Li+ seriously increases the diffusion barrier within the solid lattice, which causes more remarkable volume changes of both anode and cathode materials during the (de)intercalation processes. The heavier mass of Na+/K+ also results in a relatively lower specific capacity of both anode and cathode materials. Therefore, both SIBs and PIBs demonstrate a lower energy density, poorer rate capability and cyclic stability than LIBs, which seriously limits the development and application of both SIBs and PIBs.
Hence, scientists have made significant efforts to search for more suitable anode materials with low production cost, high specific capacity, superior rate capability, and excellent cyclic stability. Because the mass-specific capacities of anode materials are much higher than those of cathode materials, anode materials are considered as the critical limitation of the energy density of both SIBs and PIBs. As reported, carbonaceous materials exhibit higher electrical conductivity, better chemical stability, and better capability to alleviate the enormous volume expansion than alloy-based materials, metal phosphides, selenides and sulfides. Therefore, carbonaceous materials become extremely attractive anodes for SIBs and PIBs.
Defects, such as topological, vacancy, edge and complex defects, have been considered the most essential active sites for Na+ and K+ storage. On the contrary, the defect-free graphite structure is unsuitable for accommodating Na+ and K+ due to the narrow interlayer space. Therefore, researchers have applied defect engineering as an effective strategy to enhance the electrochemical performance of carbon anodes.
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BAI Ling, LIU Qian, HONG Tao, LI Hao-ran, ZHU Fang-yuan, LIU Hai-gang, LI Zi-quan, HUANG Zhen-dong (2025). Defect-rich N/O-co-doped porous carbon frameworks as anodes for superior potassium and sodium-ion batteries. SinoTechIntel Verified Research. https://doi.org/10.1016/S1872-5805(NCM2024-39-06-07)
Research & Educational Purpose Only:The translations, structured abstracts, analytical annotations, and data reports provided by SinoTechIntel are intended exclusively for academic research, internal corporate R&D, and educational benchmarking. They do not constitute formal engineering, chemical safety, legal, or professional advice.
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Frequently Asked Questions
What is the main achievement of this research?
The research developed a defect-rich porous carbon framework (DRPCF) co-doped with nitrogen and oxygen, which exhibits superior sodium and potassium storage performance, with high capacity and excellent cycling stability.
How was the DRPCF material synthesized?
The DRPCF was synthesized using porous g-C3N4 (PCN) and dopamine (DA) as raw materials, with varying PCN/DA mass ratios and carbonization temperatures. The optimal sample, DRPCF-2/1-700, was obtained at a mass ratio of 2:1 and carbonization at 700 °C in an Ar atmosphere.
What are the key factors contributing to the high performance of DRPCF-2/1-700?
The high performance is attributed to its large specific surface area, enormous pore volume, and abundant N/O heteroatom active defect sites, which enhance pseudocapacitive sodium and potassium ion storage.
How does the DRPCF-2/1-700 anode perform in half-cell tests?
In half-cell tests, Na//DRPCF-2/1-700 maintained a capacity of 328.2 mAh g−1 after 900 cycles at 1 A g−1, and K//DRPCF-2/1-700 maintained a capacity of 321.5 mAh g−1 after 1200 cycles at 1 A g−1.
What is the significance of ex-situ Raman spectroscopy in this study?
Ex-situ Raman spectroscopy confirmed that the filling and removal of K+ and Na+ from electrochemically active defects are responsible for the high capacity, superior rate, and cycling performance of the DRPCF-2/1-700 sample.
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