Advanced Carbon‐Based Anodes for Potassium‐Ion Batteries

Nitrogen doping and graphitization tuning coupled hard carbon for superior potassium-ion storage

Potassium-ion batteries (PIBs) are regarded as a potential substitute for LIBs owing to the benefits of potassium’s abundance, low cost, and high safety. Nonetheless, the practical implementation of potassium-ion batteries still encounters numerous challenges, with the selection and design of anode materials standing out as a key factor impeding their progress. Hard carbon, characterized by its amorphous structure, high specific surface area, and well-developed pore structure, facilitates the insertion/extraction of potassium ions, demonstrating excellent rate performance and cycling stability. This review synthesizes the recent advancements in hard carbon materials utilized in PIB anodes, with a particular focus on the potassium storage mechanism, electrochemical properties, and modification strategies of hard carbon. Ultimately, we present a summary of the current challenges and future development directions of hard carbon materials, with the objective of providing a reference for the design and optimization of hard carbon materials for PIBs.

S/N co-doped hierarchical porous carbon from lignite as high-performance anode for potassium-ion batteries

Introduction The urgent need to address environmental concerns, particularly the escalating plastic waste crisis, has underscored the importance of exploring innovative methods for enhancing plastic bottle recycling [1]. Among these methods, upcycling—transforming plastic waste into products of greater intrinsic value—has gained significant attention [2, 3].This study focuses on applying upcycling methods to plastic bottles, with a specific emphasis on Polyethylene terephthalate (PET) materials sourced from the Coca-Cola corporation as a case study. PET bottles are chosen due to their widespread use in consumer markets and their prevalence in plastic waste streams.The primary objective of this research is to systematically investigate processes for repurposing PET bottles into hard carbon materials. Such materials hold promise for various applications, notably in energy storage systems like lithium-ion batteries (LIBs). By examining PET dissolution in various solvents, this study aims to identify efficient and sustainable pathways for producing high-quality carbon materials.Additionally, this study integrates phosphorus (P) doping into the synthesis process. P-doping has been demonstrated to enhance the electrochemical performance of carbon materials by altering their electronic and structural properties. The authors successfully synthesized P-doped hard carbon and conducted comprehensive characterization using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectroscopy. These analyses provide insights into the effects of doping on the structure and morphology of the resulting hard carbon materials, shedding light on mechanisms behind their improved electrochemical performance.This research aims to contribute to the development of environmentally sustainable solutions for plastic waste management. Through the application of upcycling methods to PET bottles and the integration of P-doping strategies, this study seeks to address the environmental challenges posed by plastic waste while exploring avenues for value-added product creation in advanced technological domains.2. Experimental A novel approach is presented for the synthesis of hard carbon material for lithium-ion batteries (LIBs) utilizing recycled PET bottles from Coca-Cola Classic. The bottles underwent thorough washing with water and ethanol, followed by air drying and cutting into small 3-4 mm square pieces prior to dissolution. Solvents for PET dissolution were prepared by mixing dichloromethane (DCM) with trifluoroacetic acid (TFA) in a volume ratio of 3:7. The PET pieces were dissolved in the solvent mixture at a rate of 2 grams per 10 ml of solvent using a stirrer at 100 rpm for 4 hours. P-doping was achieved by adding phosphoric acid (H3PO4) to the plastic solution in various concentrations (1 mol, 2 mol, 3 mol H3PO4 per 10 ml of solution). The resulting solution was applied as a thin layer (50 μm thick) onto a glass surface and dried in air for 24 hours. Subsequently, the resulting film was annealed in an argon atmosphere at 750°C for 2 hours with a heating rate of 5 degrees/min. The resulting carbon materials were characterized and utilized as anodes for lithium-ion half-cells. Electrochemical properties of the batteries were evaluated using cyclic voltammetry (CV) and galvanostatic charge/discharge methods. This study demonstrates a sustainable and efficient method for the synthesis of carbon materials for LIBs from recycled plastic waste, with promising electrochemical performance. Results and Discussion The XRD analysis presented in Figure 1 demonstrate that the obtained carbon sample possessed the high-quality attributes required for battery-grade hard carbon which is substantiated by the distinct peaks observed. Moreover, the initial discharge capacity stands at an 758.53 mAh/g, accompanied by an initial Coloumbic efficiency of 49.75%. After the 10th cycle the Coulombic efficiency reached 97.98%. The corresponding capacitance values after the 10th and 50th cycle are 338,35 and 304,71 mA.Fig. 1 X-ray diffraction pattern of obtained powder References Olazabal, I., Goujon, N., Mantione, D., Alvarez-Tirado, M., Jehanno, C., Mecerreyes, D., & Sardon, H. (2022). From plastic waste to new materials for energy storage. <i>Polymer Chemistry</i>, <i>13</i>(29), 4222–4229. https://doi.org/10.1039/d2py00592aMirjalili, A., Dong, B., Pena, P., Ozkan, C. S., & Ozkan, M. (2020). Upcycling of polyethylene terephthalate plastic waste to microporous carbon structure for energy storage. <i>Energy Storage</i>, <i>2</i>(6). https://doi.org/10.1002/est2.201Nagmani, & Puravankara, S. (2023). Utilization of PET derived hard carbon as a battery-type, higher plateau capacity anode for sodium-ion and potassium-ion batteries. <i>Journal of Electroanalytical Chemistry</i>, <i>946</i>. https://doi.org/10.1016/j.jelechem.2023.117731 Figure 1

Design and Synthesis of Graphitic Carbon Nitride (g-C3N4) Based Materials for Rechargeable Batteries

Status of rechargeable potassium batteries

Control of the structure and composition of nitrogen-doped carbon nanofoams derived from CO2 foamed polyacrylonitrile as anodes for high-performance potassium-ion batteries

Loofah-derived carbon as an anode material for potassium ion and lithium ion batteries

The study explores graphitic carbon cones and discs as anode materials for sodium-ion (Na-ion) batteries. These unique structures, produced via scalable pyrolysis of hydrocarbons, offer a promising alternative to conventional graphite and hard carbons. While graphite is widely used in lithium-ion batteries, it exhibits poor performance for Na-ion batteries due to the size mismatch between Na ions and graphite's interlayer spacing. Hard carbons, on the other hand, have limitations like low initial Coulombic efficiency and uncertain sodium storage mechanisms.The carbon cones and discs are composed of pure graphitic material with ordered domains and a morphology suitable for accommodating larger ions like Na+. Characterization techniques such as TEM, XRD, Raman spectroscopy, and XPS confirm the material's high graphitic quality and minimal structural defects. The carbon cones demonstrated reversible capacities of ~230 mAh g⁻¹ at 20 mA g⁻¹, with excellent rate performance. Long cycling tests showed remarkable stability, retaining 95% of capacity after returning to initial current rates (Figure 1a, b), even under high active mass loading. However, the capacity was slightly lower due to challenges like SEI formation and electrolyte consumption. Ex-situ solid-state NMR and TEM analyses provided evidence of Na+ intercalation into the graphitic lattice. These processes occur with negligible volume expansion, ensuring long-term structural stability. When paired with NaFePO₄ cathodes, the carbon cone anodes achieved specific capacities of ~123.8 mAh g⁻¹ after 50 cycles, demonstrating their practical viability. The material is derived from industrial-scale processes using byproducts from oil and gas industries, making it a cost-effective and sustainable option for future battery technologies.This study highlights the potential of graphitic carbon cones and discs as high-performance anode materials for Na-ion batteries. Their unique structure overcomes the limitations of traditional graphitic and hard carbon materials, offering a viable pathway for the commercialization of beyond-lithium battery chemistries.

Sodium-ion batteries (SIBs) have significant potential for applications in portable electric vehicles and intermittent renewable energy storage due to their relatively low cost. Currently, hard carbon (HC) materials are considered commercially viable anode materials for SIBs due to their advantages, including larger capacity, low cost, low operating voltage, and inimitable microstructure. Among these materials, renewable biomass-derived hard carbon anodes are commonly used in SIBs. However, the reports about biomass hard carbon from basic research to industrial applications are very rare. In this paper, we focus on the research progress of biomass-derived hard carbon materials from the following perspectives: (1) sodium storage mechanisms in hard carbon; (2) optimization strategies for hard carbon materials encompassing design, synthesis, heteroatom doping, material compounding, electrolyte modulation, and presodiation; (3) classification of different biomass-derived hard carbon materials based on precursor source, a comparison of their properties, and a discussion on the effects of different biomass sources on hard carbon material properties; (4) challenges and strategies for practical of biomass-derived hard carbon anode in SIBs; and (5) an overview of the current industrialization of biomass-derived hard carbon anodes. Finally, we present the challenges, strategies, and prospects for the future development of biomass-derived hard carbon materials.

A hard carbon material with free-standing porous structure and high contents of heteroatom functional groups is considered to be a potential anode for potassium-ion batteries (PIBs). Herein, a free-standing phosphorus/nitrogen cofunctionalized porous carbon monolith (denoted as PN-PCM) anode for PIBs is successfully fabricated via a supercritical CO2 foaming technology, followed by amidoximation, phosphorylation, and thermal treatment. Thanks to the synergistic effect of a three-dimensional macroporous open structure and high P/N contents of 6.19/5.74 at%, the PN-PCM anode delivers an excellent reversible specific capacity (396 mA h g-1 at 0.1 A g-1 after 300 cycles) with high initial Coulombic efficiency (63.6%), a great rate performance (168 mA h g-1 at 5 A g-1), and an ultralong cycling stability (218 mA h g-1 at 1 A g-1 after 3000 cycles). Theoretical calculations clarify that in a P/N cofunctionalized carbon, the P-C bonds devote more to enhancing the potassium storage via adsorption and improving electronic conductivity of carbon, while P-O bonds contribute more to enlarging the interlayer distance of carbon and reducing the ion diffusion barrier.

Improvement in potassium ion batteries electrodes: Recent developments and efficient approaches

Designing carbon anodes for advanced potassium-ion batteries: Materials, modifications, and mechanisms

Lithium-ion batteries (LIBs) power most of the portable electronic devices nowadays. However, the geographically limited lithium resources have led to the rapid rise of the battery price. Therefore, new battery technologies that do not rely on lithium must be developed.Sodium-ion batteries (NIBs) are one of the promising alternatives that can replace LIBs, because of not only the abundance of sodium resources but also the significantly lower cost of sodium than lithium. To develop the NIB technology, it is imperative to find a suitable anode material that can reversibly interact with sodium ions. Amongst the available anode materials reported in the literature, carbonaceous materials are promising. While graphite has been successfully used as the anode for LIBs, it shows very poor performance for NIBs owing to the larger ionic radius of sodium than lithium, making the former difficult to intercalate into graphite. Therefore, carbon materials with an enlarged interplanar separation that can accommodate larger sodium ions would make it a suitable candidate as anodes for NIBs. Hard carbon materials derived from biomass have been shown to hold a great promise for NIBs in this regard. Biomass is a widely available resource, especially in Australia. Utilising such naturally abundant biomass precursors for producing carbon material lowers the reliance on non-renewable fossil fuel resources, thus making material production sustainable and economic. In addition, such hard carbons derived from biomass have larger interlayer spacing and defects which allow efficient sodium-ion storage. Therefore, this PhD project aims to develop such biomass-based hard carbon anode materials for NIBs.Research results collected in this thesis project have shown that biomass-derived carbon materials display promising electrochemical properties in both LIB and NIB cells. It was found in this project that flame deposited carbon nanoparticles from coconut oil exhibited a second-cycle discharge capacity of about 277 mA h g-1 in NIBs and of about 741 mA h g-1 in LIBs at a current density of 100 mA g-1. Good cycling stability, rate performance, and high coulombic efficiency are the key properties of the carbon nanoparticles. In another work, binder-free carbon electrodes with a three-dimensional architecture prepared by using a one-step fabrication protocol delivered a specific discharge capacity of 764 mA h g-1 at a current density of 50 mA g-1 with an exceptional cycling stability in a LIB cell. In a NIB cell, the electrode exhibited a discharge capacity of 241 mA h g-1 in the second cycle at a current density of 50 mA g-1 and remained stable over prolonged cycling.Further, the focus of the thesis was laid on improving the performance of such carbon materials for NIBs. Spinifex nanocellulose derived hard carbons were prepared and used as anodes for NIBs. This carbon produced by using a low-temperature carbonization protocol delivered a superior performance as an anode for NIBs with a specific capacity of 386 mA h g-1 at 20 mA g-1 on par with graphite-based anodes for LIBs. To further enhance the performance of such carbon anodes for NIBs, a raw mango powder derived carbon material enriched with nitrogen-containing functional groups was developed for NIBs. A reversible specific capacity of ~520 mA h g-1 at a current density of 20 mA g-1 along with an excellent rate performance were obtained. When cycled at a high current density of 1 A g-1, the nitrogen-rich carbon was stable for over 1000 cycles delivering a capacity of ~204 mA h g-1. In all, the thesis brings out the importance of biomass-derived carbons for rechargeable batteries and puts forth synthesis and optimisation strategies for improving the electrochemical properties of such carbons for NIBs.In summary, this thesis successfully demonstrates different synthesis strategies to prepare biomass derived hard carbon materials as anodes for rechargeable batteries. Such carbon materials produced from biomass are cost-effective and sustainable. Novel strategies like flame-deposition methods have been implemented in the present thesis project to prepare carbon nanoparticles with superior electrochemical performance in LIBs and NIBs. In addition, a scalable carbon production from native Australian biomass spinifex was demonstrated as superior anodes for NIBs. The microstructure of hard carbons reported in the thesis revealed that larger interlayer spacing and defects enhance the sodium-ion storage. Strategies to further improve the performance of such carbon materials by introducing heteroatoms like nitrogen was successfully demonstrated in the thesis. The works presented in the thesis could inspire future research in exploring such hard carbon material with tunable surface chemistries for sodium-ion storage.

Nitrogen and sulfur co-doped graphene nanoribbons with well-ordered stepped edges for high-performance potassium-ion battery anodes