Porous Hard Carbon Research Articles

N/P/O co-doped porous carbon derived from agroindustry waste of peanut shell for sodium-ion storage

Porous bio‑carbon from agroindustry waste behaves one of the most promising anode materials for sodium-ion batteries (SIBs) because of its high sodium storage capacity, low cost, sustainability, and low charge/discharge voltage platform. Herein, we have developed a new N/P/O co-doped porous hard carbon derived from peanut shell (PSCNP) synthesized via KOH activation, hydrothermal doping combined with carbonization method, using chitosan as nitrogen source, phytic acid as phosphorus source, and peanut shell as carbon and oxygen source. Through seriously regulating the calcination temperature, the optimal PSCNP-800 carbonization at 800 °C can well combine the advantages of the natural rich porous microstructure of peanut shells, large graphite interlayer spacing (0.379 nm), and short diffusion distance for sodium-ion. As an advanced anode for SIBs, the PSCNP-800 delivered a reversible capacity of 248.8 mAh g−1 after 100 cycles at 25 mA g−1. This work could provide a possible idea for the preparation of N/P/O co-doped porous hard carbon from low-cost agroindustry waste as anodes for SIBs.

Utilizing porous carbon composites based on biomass for lithium battery negative electrodes

This work used high-temperature calcination techniques along with basic chemical processing to produce a range of porous carbon compounds from biomass. After that, these substances were employed as anodes in lithium-ion batteries. The first hard carbon was produced via the dehydration reaction of strong sulfuric acid with sucrose (R-HC), then annealing in an NH3Ar environment was used to obtain the nitrogen-doped porous hard carbon (N-HC). Because N-HC has a high interlayer spacing (ca. 0.39 nm) and an abundant ultra-microporous structure (pore size < 0.75 nm), the lithium-ion diffusion coefficient in N-HC can reach up to 9.0 × 10−8 cm2.s−1. The obtained porous carbon compounds contain a rich pore structure, many functional groups, and a high specific surface area, according to the results. Following their application to the anode of lithium-ion batteries, they demonstrate favorable cycle stability and electrochemical performance. Furthermore, a detailed investigation into the kinetic characteristics of the lithium-ion diffusion behavior in the electrodes revealed that the porous carbon materials’ electrodes exhibited greater surface diffusion behavior for Li+.

Interplay of Size and Magnetic Effects in Electrocatalytic Water Oxidation Activity of Sub-10 nm NiOx Supported Porous Hard-Carbons.

This report describes a systematic approach for precise engineering of a catalyst-metal oxide interface through combining complementary approaches of chemical vapor deposition and atomic layer deposition. Specifically, Chemical Vapor Deposition (CVD) fabricated nanostructured hard-carbon framework (NCF) is employed as synergistic support for precise deposition of NiOx particles through Atomic Layer Deposition (ALD). The three variants of NCF-NiOx system (dimensions ranging from 3-12 nm, surface coverage ranging from 0.14 %-2 %) achieved exhibit unique electrocatalytic water oxidation activities, that are further strongly influenced by an external magnetic field (Hext). This confluence of size engineering and associated magnetic field effects interplay to produce the largest lowering in Rct at Hext=200 mT. A comprehensive analysis of electrocatalytic parameters including the Tafel slope and double layer capacitance establishes further insights on co-relation of size effect and magnetic properties to understand the role of nanocarbon supported transition metal oxides in water electrolysis.

Synthesizing hard carbon anodes for potassium-ion batteries from black liquor and deinking sludge

Porous hard carbon anodes, with large interlayer space and high adsorption ability, can offer much better cycle stability and higher discharge capacity for potassium-ion batteries compared to commercial graphite anodes. However, most commercial hard carbons are synthesized from relatively expensive high-molecular polymers. In this study, pulping and papermaking wastes were utilized as precursors for producing hard carbons and pore-enlarging agent, respectively. Specifically, after thorough mixing through ball milling, black liquor solids and deinking sludge were utilized to produce porous hard carbon anodes via co-pyrolysis. The results show that direct pyrolysis of black liquor can produce hard carbons efficiently, eliminating the need to extract lignin from black liquor. Moreover, it is shown that the pore-enlarging agent derived from deinking sludge can enlarge much portion of pores on hard carbons, resulting in abundant mesopores. Electrochemical tests demonstrate that the synthesized porous hard carbon anodes can achieve highest specific capacity of 303.5 mAh g−1 at 100 mA g−1 using a 1.0 M potassium hexafluorophosphate electrolyte in a mixture of diethyl carbonate and ethylene carbonate. Additionally, the synthesized porous hard carbon anodes exhibit low average capacity decay per cycle of 0.06 % at 100 mA g−1 when tested with a 1.0 M potassium bis(fluorosulfonyl)imide electrolyte in the same solvent mixture after 500 cycles. Therefore, recycling black liquor and deinking sludge to produce porous hard carbon anodes for potassium-ion batteries is a promising approach for environmental and energy sustainability.

F, O co-doped porous hard carbon from conjugated microporous polymer for efficient lithium storage

Hard carbon is a promising alternative to conventional graphite due to its adjustable chemical composition and amorphous structure. Herein, F, O co-doped hard carbon (FOPHC) is constructed from F-containing conjugated microporous polymers, which is synthesized from 1,3,5-triethynylbenzene and 1,4-dibromotetrafluorobenzene. BET, XPS, and EDS analyses demonstrate that FOPHC is a nanoparticle with a hierarchical pore structure and F, O co-doping. When evaluated as an anode for LIBs, the FOPHC delivers an impressive 781 mA h g−1 at 0.1 A/g and 420 mA h g−1 at 0.6 A/g after 300 cycles. Kinetic calculation reveals that the dominated pseudocapacitance contribution of Li-storage in FOPHC (67.5 %, at 1.0 mV/s), attributed to the well-developed hierarchical pore structure and abundant defect sites. This work provides original insights for the microstructure regulation and design of hard carbon.

NaF Modification of Open/Closed Pores Enhancing the Sodium Storage in Hard Carbon

Hard carbon (HC) is one of the most promising anode materials in sodium‐ion batteries, and its sodium‐storage performance is closely related to its open/closed pore structures. However, modification of the inner pore structure of HC still remains a challenge. In this work, porous HCs are synthesized using pitch as the precursor, and the open and closed pores in HC are modified by NaF to obtain NaF@HC and polypropylene (PP)@NaF@HC, respectively. In the results, it is proved that NaF modification can construct closed pores in HC and improve Na+ transportation. Furthermore, NaF modification of the open pores effectively inhibits the electrolyte decomposition. Both NaF@HC and PP@NaF@HC exhibit excellent sodium‐storage performance, which delivers the reversible specific capacities of 310 and 323 mAh g−1, corresponding to the initial Coulombic efficiency (ICE) of 72.3% and 82.2%, respectively. Even after 200 cycles, their capacity retentions still maintain 99.5% and 92.8%. Nevertheless, NaF modification of the closed pores increases the sodium deposition barrier, leading to a severe capacity fading of the plateau capacity at a high current rate. In this study, the structural regulation of open and closed pores in HC can be guided, thereby improving its sodium‐storage kinetics.

Rationalizing the Role of Polyoxometalate‐Based Gel–Polymer Electrolytes to Achieve Five‐Fold Increase in the Specific Capacitance of Hard‐Carbon‐Based Supercapacitors

Boosting the charge‐transport pathways in gel–polymer electrolytes (GPEs) is important to extract their full potential for non‐Faradaic, supercapacitive energy‐storage devices. Herein, a series of polyoxometalates (POMs) ([P6W18O79]20−, [PW9O34]9− and [PW12O40]3−) as electrochemical polarization promoters is demonstrated to achieve 15‐fold enhancement in ionic conductivity of 1‐butyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide‐based GPEs. Fundamentally, the three POMs offer systematically differing charge densities (200, 45, and 6.5 e− nm−3) that are linearly correlated to the observed enhancements in ionic conductivities. The charge density on the POMs contributes to the formation of additional charge‐migrative pathways across the GPE, as evidenced from facile polarization characteristics. Importantly, the presence of POM beyond a critical concentration acts as charge‐trapping centers to impede the ionic conductivity of the GPEs. The insights obtained through such detailed spectroscopic and electrochemical techniques are integrated into full‐scale supercapacitive devices with a rationally designed porous hard carbon as the electrode material. The resulting electrode–electrolyte interface synergies achieve a best‐in‐class supercapacitor exhibiting energy density of 58 Wh kg−1, power density of 14 kW kg−1, and a relaxation time constant of 0.66 s, without compromising on cycling stability for direct integration with intermittent energy‐harvesting devices. Thus, the fundamental insights presented here outline the design principles for extracting high‐performance from GPE‐based energy‐storage devices.

Carbons Derived from Regenerated Spherical Cellulose as Anodes for Li-Ion Batteries at Elevated Temperatures.

Biomass-based materials have emerged as a promising alternative to the conventional graphite anode in Li-ion batteries due to their renewability, low cost, and environmental friendliness. Therefore, a facile synthesis method for porous hard carbons based on cellulose acetate microspheres and bead cellulose is used, and their application as anode materials in Li-ion batteries is discussed. The resulting porous carbons exhibit promising electrochemical characteristics, including a reversible capacity of about 300 mAh g-1 at 0.1 C (37 mA g-1) after 50 cycles, and stable capacities up to 210 mAh g-1 over 1000 cycles at 1 C (372 mA g-1) in half-cells for cellulose acetate microspheres carbonised at 1200 °C. Moreover, at 60 °C cellulose-derived carbons show higher specific capacities than graphite (300 mAh g-1 vs 240 mAh g-1 at 1 C after 500 cycles), indicating their potential for use in high-temperature applications. The different charge storage mechanisms of the prepared hard carbon materials and graphite are observed. While capacity of graphite is mainly controlled by the Faradaic redox process, the cellulose-derived carbons combine Faradaic intercalation and capacitive charge adsorption.

Chinese baijiu spent grains-based high-performance porous hard carbon for sodium-ion battery anodes

Chinese baijiu spent grains-based high-performance porous hard carbon for sodium-ion battery anodes

New frontiers in alkali metal insertion into carbon electrodes for energy storage.

With rising interest in new electrodes for next-generation batteries, carbon materials remain as top competitors with their reliable performance, low-cost, low voltage reactions, and diverse tunability. Depending on carbon's structure, it can attain high cyclability as with Li+ at crystalline graphite or exceptional capacities with Na+ at amorphous, porous hard carbons. In this review, we discuss key results and research directions using carbon electrodes for alkali ion storage. We start the first section with hard carbon (HC), a leading material of interest for next-generation Na-ion batteries. Methods for tuning the HC structure towards a high capacity pore-filling mechanism are examined. The rate performance of hard carbon electrodes is further discussed. We finish this section with soft carbons that mostly remain as low performing materials compared to other carbons. In the second section, we discuss alkali ion insertion into graphite and graphite-like materials. Though graphite has a long history with Li-ion batteries, it also shows promising characteristics for K-ion batteries. We discuss the significant progress made on improving the electrolyte for high cyclability of graphite with K+. Thereafter, we evaluate B/C/N materials that have a similar structure to graphite but can attain higher capacities for both Li+ and Na+. Finally, we touch on the recent developments using alternative solvents for Na+ cointercalation at graphite and deeper knowledge on the intercalant structure. Despite steady progress, carbon electrodes continue to improve as a key group of materials for alkali energy storage.

3D Printed Freestanding Electrodes for High Energy Density Batteries

The global surge in energy consumption, as well as a rise in greenhouse gases, has created an urgent need for high-capacity battery materials to store intermittent, renewable energy sources such as wind and solar. Directly increasing electrode mass loading using the traditional slurry coating fabrication process introduces unavoidable issues such as slowed kinetics and thermal degradation. Freestanding electrodes are a great alternative as they eliminate the need for inactive components (i.e., binder, additive carbon, and current collector) and shorten the fabrication process. In this work, carbon microlattice templates are designed and fabricated through the use of 3D stereolithography, which allows for design flexibility of any shape or geometry, followed by pyrolysis to create porous hard carbon. These hard-carbon templates are then subjected to a ferrocene/sulfur reaction to grow iron sulfide that serves as active material, which has a theoretical specific capacity higher than that of commercial graphite. The design utilizes controlled microchannels that facilitate ion transport through charging and discharging cycles. The addition of FeS led to a specific capacity of 1204.2 mAh g-1 during cycle two with a current density of 500 mA g-1, which is much higher than that achieved with the control carbon template (≈37.3 mAh g-1 at 300 mA g-1). These results will advance the development of composite electrodes as well as shine light on the immense potential to develop high energy density batteries utilizing 3D printing.

An aqueous BiI3-Zn battery with dual mechanisms of Zn2+ (de)intercalation and I−/I2 redox

The development of aqueous battery with dual mechanisms is now arousing more and more interest. The dual mechanisms of Zn2+ (de)intercalation and I−/I2 redox bring unexpected effects. Herein, differing from previous studies using ZnI2 additive, this work designs an aqueous BiI3-Zn battery with self-supplied I−. Ex situ tests reveal the conversion of BiI3 into Bi (discharge) and BiOI (charge) at the 1st cycle and the dissolved I− in electrolyte. The active I− species enhances the specific capacity and discharge medium voltage of electrode as well as improves the generation of Zn dendrite and by-product. Furthermore, the porous hard carbon is introduced to enhance the electronic/ionic conductivity and adsorb iodine species, proven by experimental and theoretical studies. Accordingly, the well-designed BiI3-Zn battery delivers a high reversible capacity of 182 mA h g−1 at 0.2 A g−1, an excellent rate capability with 88 mA h g−1 at 10 A g−1, and an impressive cyclability with 63% capacity retention over 20 K cycles at 10 A g−1. An excellent electrochemical performance is obtained even at a high mass loading of 6 mg cm−2. Moreover, a flexible quasi-solid-state BiI3-Zn battery exhibits satisfactory battery performances. This work provides a new idea for designing high-performance aqueous battery with dual mechanisms.

Engineering Ultrathin Carbon Layer on Porous Hard Carbon Boosts Sodium Storage with High Initial Coulombic Efficiency.

Hard carbon (HC) has been widely adopted as the anode material for sodium ion batteries (NIBs). However, it is troubled by a low initial Coulombic efficiency (ICE) due to its porous structure. Herein, a graphitized and ultrathin carbon layer coating on HC is proposed to solve this challenge. The as-prepared porous carbon material coated with an ultrathin carbon layer composite (PCS@V@C) exhibits a cavity structure, which is prepared by using bis(cyclopentadienyl) nickel (CP-Ni) as the carbon source for outer coating, glucose carbon spheres as porous carbon, and introducing a silica layer to facilitate the coating process. When utilized as the anode for NIBs, the material shows an ICE increase from 47.1% to 85.3%, and specific capacity enhancement at 0.1 A g-1 from 155.3 to 216.7 mA h g-1. Moreover, its rate capability and cycling performance are outstanding, demonstrating a capacity of 140.3 mA h g-1 at 10 A g-1, and a retaining capacity of 225.6 mA h g-1 after 300 cycles at 0.1 A g-1 with the Coulombic efficiency of 100% at the second cycle. The excellent electrochemical performance of the PCS@V@C is attributed to the ultrathin carbon layer, which is beneficial for the formation of a stable solid electrolyte interphase (SEI) film. Therefore, this study provides a feasible surface modification method for the preparation of anode materials for NIBs with high specific capacity and ICE.

Modulating electronic structure with heteroatom dopants in porous hard carbon towards ultralong lifespan sodium-ion batteries

Hard carbon (HC) has been recognized as one of the most mature and commercialized anode materials for sodium-ion batteries (SIBs). However, it still faces problems such as low reversible capacity, poor rate capability and cycling stability for commercial applications. Herein, we propose a systematic investigation into heteroatom-doped engineering for tailoring the electronic structure of N-doped carbon by integrating heterogeneous atoms (S/P) into 3-dimensional (3D) interconnected porous HC. Thus-fabricated N/P dual-doped HC (NPDC) exhibits improved electronic conductivity and expanded interlayer spacing, which endows high rate capability and prolonged cycle life over 28,000cycles for SIBs (1400 h lifespan at 5.0 A/g). Theoretical and experimental results unravel that the electron-donating ability of P atoms with unmatched p orbital slightly change the spin density optimizes the adsorption energy and electronic structure to balance the Na+ adsorption/intercalation in NPDC. The “adsorption/intercalation” mechanism of Na+ in the NPDC is also illustrated by a detailed correlation analysis between electrochemical kinetics analysis and spectral information. Moreover, the corresponding pouch full battery delivers a high energy density of 254.7 Wh kg−1 with excellent rate capability and outstanding cycle stability (89.0% capacity retention) after 500cycles at 1.0C. This work provides a feasible approach to finely modulate the electronic structure of porous HC and facilitate the future design of printable carbon-based SIBs anodes.

Hierarchical porous hard carbon derived from rice husks for high-performance sodium ion storage

Hierarchical porous hard carbon derived from rice husks for high-performance sodium ion storage

Free-Standing, Self-Doped Porous Hard Carbon: Na-Ion Storage with Enhanced Initial Coulombic Efficiency.

The use of porous hard carbons (PHCs) as electrode materials in sodium-ion batteries has great potential; however, the exposure of large surface areas to electrolyte flow results in irregular and irreversible solid electrolyte interfaces (SEIs), leading to deteriorated ionic and electronic mobility and inferior initial Coulombic efficiency (ICE). These issues can be addressed through suitable structural modifications of PHC materials. Herein, the integration of high-surface-area PHCs with carbon nanofibers (CNFs) was accomplished by a simple electrospinning technique, which resulted in a uniform and reversible SEI layer. In the meantime, the CNFs' mesh provided connectivity and conductivity in the as-integrated electrodes, whereas PHCs offered fast diffusion kinetics and high Na+ ion storage capacity. Additionally, PHC integration with CNFs demonstrated an excellent ICE of 77% and a specific capacity of 505 mAh/g at 25 mA/g. Furthermore, the conjugated microstructure also provided flexibility and stability to the electrode (260 mAh/g after 500 cycles). This remarkable synergy may promote the development of free-standing, flexible, and highly porous properties in a single material for advanced energy storage applications.

Sb/N‐Doped Carbon Nanofiber as a Sodium‐Ion Battery Anode

The electrochemical performance of sodium‐ion battery (SIB), which is considered to have high potential to replace the lithium‐ion battery, in cycling stability at large current density needs to be improved. Herein, a hybrid of antimony nanoparticles and nitrogen‐doped hollow porous hard carbon nanofiber (Sb/N‐HPCNF) is synthesized through electrospinning and in situ replacement. As an anode of SIB, Sb/N‐HPCNF presents excellent cycling stability (281 mAh g−1 after 2000 cycles at 2 A g−1). Such a performance mainly stems from the hollow porous structure, which promotes the electrolyte diffusion along the pores and provides more active sites for Na+ insertion/extraction. This work provides an ingenious strategy for constructing well‐designed structures for advanced energy storage technology.

Improved Na-ion kinetics of 1T MoS2 nanopatterned porous hard carbon as an ultra-long life anode

Porous hard carbons (PHC) are promising anode materials in sodium-ion batteries; however, the availability of large surface area creates numerous irreversible active sites that cause rapid initial cycle capacity fading and electrode degradation, resulting in lower specific capacity and poor cycle stability. PHC surface modification via 2D transition metal dichalcogenides is a synergistic approach to combine excellent electrochemical properties of both materials and resolve these issues. Therefore, we designed 1T MoS2 nanopatterned PHC skeleton using carbonization and hydrothermal treatment of biomass (chickpea husk). As a result, HC@MoS2-II electrode with extended d002 spacing of MoS2 nanolayers (0.650 nm) exhibited an excellent specific capacity of 470 mAh/g at 50 mA/g with high initial coulombic efficiency (63%) and ultra-long cycle stability (190 mAh/g) at 1000 mA/g over 3500 cycles. The extraordinary electrochemical performance can be attributed to the synergistic assembly, where the high surface area PHC skeleton effectively buffered large volume expansion during charging/discharging, and 1T MoS2 nanoflowers added fast ionic diffusion kinetics and PHC surface protection.

Hard Carbon Derived from Avocado Peels as a High-Capacity, Fast Na+ Diffusion Anode Material for Sodium-Ion Batteries

Deriving battery grade materials from natural sources is a key element to establishing sustainable energy storage technologies. In this work, we present the use of avocado peels as a sustainable source for conversion into hard carbon-based anodes for sodium ion batteries. The avocado peels are simply washed and dried then proceeded to a high temperature conversion step. Materials characterization reveals conversion of the avocado peels in high purity, highly porous hard carbon powders. When prepared as anode materials they show to the capability to reversibly store and release sodium ions. The hard carbon-based electrodes exhibit excellent cycling performance, namely, a reversible capacity of 352.55 mAh g−1 at 0.05 A g−1, rate capability up to 86 mAh g−1 at 3500 mA g−1, capacity retention of >90%, and 99.9% coulombic efficiencies after 500 cycles. Cyclic voltammetry studies indicated that the storage process was diffusion-limited, with diffusion coefficient of 8.62 × 10−8 cm2 s−1. This study demonstrates avocado derived hard carbon as a sustainable source that can provide excellent electrochemical and battery performance as anodes in sodium ion batteries.

Porous Hard Carbon as High-Performance Electrode Material for Supercapacitors: Towards Sustainable Approach

Bio-waste, coco peat is utilized to produce high performance, hard carbon supercapacitor electrodes. Combined pyrolysis and activation methods are adopted to produce coco peat derived porous hard carbon. Structural analysis confirms the formation of hard carbon. Brunauer–Emmett–Teller (BET) measurements and microscopy images reveals the presence of micro and mesoporous structure with the pore size and pore volume of 10 nm and of 0.4226 cm3 g−1. The synthesized material produces excellent capacitance and stability and exhibits the specific capacitance of 422 F g−1 and 332 F g−1 at the scan rate of 1 mV s−1 and current density of 1 A g−1. The capacity retention after 5000 cycles is 96.02%. The porous structure increases the electrolyte penetration and the large surface area facilitates electron transfer and charge diffusion kinetics.