Interconnected Carbon Network Research Articles

Rational Design of 3D Hierarchical Fe3S4 for Superior Sodium‐Ion Battery Anode Material

AbstractAmong various transition metal sulfides, iron‐based sulfides have attracted wide attention due to their abundant resources, low cost, and non‐toxicity, showing considerable research value in the field of secondary batteries. Thereinto, Fe3S4 has a high theoretical specific capacity of 785 mAh g−1. However, at present, the research related to Fe3S4 anode for sodium‐ion batteries (SIBs) is still in its infancy, and it also suffers from severe volume expansion and limited preparation. Therefore, to further boost its sodium storage potential, the Fe3S4@rGO composite with hierarchical structure and carbonaceous network is proposed in this study. Beneficial from the ingenious hierarchitectures and flexible graphene coating, the Fe3S4@rGO anode exhibits outstanding sodium storage performance, which can deliver a high capacity of 603 mAh g−1 after 1500 cycles with a superior capacity retention of 98%. The micron flower‐like structure composed of 2D nanosheets can provide sufficient active sites and promote the rapid transport of Na+. Meanwhile, the 3D interconnected graphene carbon network makes a crucial contribution to alleviating volume changes and enhancing electrical conductivity. This work reveals the application potential of Fe3S4 as an anode electrode for SIBs and provides available insights for the development of other electrode materials.

Hollow Core-Shelled Na4Fe2.4Ni0.6(PO4)2P2O7 with Tiny-Void Space Capable Fast-Charge and Low-Temperature Sodium Storage.

Iron-based mixed polyanion phosphate Na4Fe3(PO4)2P2O7 (NFPP) is recognized as a promising cathode for Sodium-ion Batteries (SIBs) due to its low cost and environmental friendliness. However, its inherent low conductivity and sluggish Na+ diffusion limit fast charge and low-temperature sodium storage. This study pioneers a scalable synthesis of hollow core-shelled Na4Fe2.4Ni0.6(PO4)2P2O7 with tiny-void space (THoCS-0.6Ni) via a one-step spray-drying combined with calcination process due to the different viscosity, coordination ability, molar ratios, and shrinkage rates between citric acid and polyvinylpyrrolidone. This unique structure with interconnected carbon networks ensures rapid electron transport and fast Na+ diffusion, as well as efficient space utilization for relieving volume expansion. Incorporating regulation of lattice structure by doping Ni heteroatom to effectively improve intrinsic electron conductivity and optimize Na+ diffusion path and energy barrier, which achieves fast charge and low-temperature sodium storage. As a result, THoCS-0.6Ni exhibits superior rate capability (86.4 mAh g-1 at 25 C). Notably, THoCS-0.6Ni demonstrates exceptional cycling stability at -20 °C with a capacity of 43.6 mAh g-1 after 2500 cycles at 5 C. This work provides a universal strategy to design the hollow core-shelled structure with tiny-void space cathode materials for reversible batteries with fast-charge and low-temperature Na-storage features.

Hollow Core‐Shelled Na4Fe2.4Ni0.6(PO4)2P2O7 with Tiny‐Void Space Capable Fast‐Charge and Low‐Temperature Sodium Storage

AbstractIron‐based mixed polyanion phosphate Na4Fe3(PO4)2P2O7 (NFPP) is recognized as a promising cathode for Sodium‐ion Batteries (SIBs) due to its low cost and environmental friendliness. However, its inherent low conductivity and sluggish Na+ diffusion limit fast charge and low‐temperature sodium storage. This study pioneers a scalable synthesis of hollow core–shelled Na4Fe2.4Ni0.6(PO4)2P2O7 with tiny‐void space (THoCS‐0.6Ni) via a one‐step spray‐drying combined with calcination process due to the different viscosity, coordination ability, molar ratios, and shrinkage rates between citric acid and polyvinylpyrrolidone. This unique structure with interconnected carbon networks ensures rapid electron transport and fast Na+ diffusion, as well as efficient space utilization for relieving volume expansion. Incorporating regulation of lattice structure by doping Ni heteroatom to effectively improve intrinsic electron conductivity and optimize Na+ diffusion path and energy barrier, which achieves fast charge and low‐temperature sodium storage. As a result, THoCS‐0.6Ni exhibits superior rate capability (86.4 mAh g−1 at 25 C). Notably, THoCS‐0.6Ni demonstrates exceptional cycling stability at −20 °C with a capacity of 43.6 mAh g−1 after 2500 cycles at 5 C. This work provides a universal strategy to design the hollow core–shelled structure with tiny‐void space cathode materials for reversible batteries with fast‐charge and low‐temperature Na‐storage features.

Taming the anchor and conversion of polyselenides with a self-reinforcing host in lithium–selenium batteries

Energy-dense lithium–selenium (Li–Se) batteries have attracted increasing attention, while their practical application is still hindered, highly relating to the volume expansion and shuttle of Li polyselenides (LiPSes). Herein, a concurrent anchoring/converting strategy is proposed to restrain the dissolution and realize the rapid conversion of LiPSes. A prototypical regulator comprises of polar catalysts embedded in the interconnected porous muti-walled carbon network (i.e., CoSnO3 nanocubes/CNTs), which promises fast electron/ion transportation and inhibits volumetric effect. Moreover, CoSnO3 as redox accelerator enables the stretched Se−Se bonds to decrease the LiPSes bidirectional conversion barrier, achieving accelerated reaction kinetics. Consequently, the self-reinforcing optimized cathode exhibits superior initial capacity of 730 mAh/g, greatly enlarged capacity after 200 cycles (increase by ∼ 32 % than that of the cell with CNTs), and superior rate capacity (153 mAh/g at 2C). This work uncovers the roles of electronic/ionic conductivity and adsorption/catalysis in Li–Se batteries, providing a guidance for taming the utilization and kinetics of cathode from material perspectives.

Pore engineering in robust carbon nanofibers for highly efficient capacitive deionization

Capacitive deionization (CDI) is considered as a revolutionary desalination method to alleviate the global water crisis. However, the current carbon-based CDI cells are constrained by the inferior desalination efficiency, resulting from the undesirable pore structure and sluggish electron/ion transport. Herein, a new porogen of silicalite-1 is proposed for the tailorable fabrication of flexible porous carbon nanofibers (PCNFs) by electrospinning, carbonization and alkali etching, where the surface area, total pore volume, mechanical robustness, specific capacitance, and electrosorption performance of the developed PCNFs are associated with the silicalite-1 dosage. The symmetric CDI unit assembled by the freestanding PCNF membrane electrodes shows a state-of-the-art desalination capacity (38.64 mg g−1), a remarkable salt removal rate (12.1 mg g−1 min−1), a desirable charge efficiency (82.36 %), an acceptable energy consumption (0.668 Wh g−1), and a satisfactory cyclic durability, and such excellent deionization performance can be explained by that the abundant hierarchical pores, the large accessible surface area, and the interconnected conductive carbon network effectively expedite the electron/ion transport. Additionally, the home-made CDI device has a favorable desalination capability toward the high-ion concentration seawater from the Yellow Sea (Xiaomai Island). This work not only validates the feasibility of silicalite-1 as the pore-forming agent for the targeted preparation of flexible PCNFs, but also it highlights the potential of pore engineering in freestanding PCNFs for advanced CDI.

Fabrication of honeycomb-like amorphous carbon-encapsulated Si nanoparticles/graphene composite for superior lithium storage

Silicon (Si) anodes have great potential for high-energy lithium-ion batteries (LIBs). However, poor electrical conductivity, high cost and huge volume change during the (de)lithiation processes of silicon anodes hinder the practical application. Herein, we demonstrate a facile and scalable approach to fabricate a porous honeycomb-like amorphous carbon-encapsulated Si nanoparticles/graphene composite via a sol-gel & CO2-introduced magnesiothermic reduction method. The greenhouse gas CO2 is efficiently transformed into carbon layers. Interconnected carbon network consisting of graphene sheets and amorphous carbon layers not only significantly improves the electrical conductivity and mechanical properties of the Si-based composites, but also provides the strong interaction between Si and carbon materials. Besides, both unique honeycomb-like porous structure and interconnected carbon network can butter large volume effects of Si nanoparticles. The as-prepared amorphous carbon-encapsulated Si/graphene anode with the carbon content of 8 wt% has excellent rate performance and outstanding cycling stability, delivering a high discharge capacity of 908 mAh g−1 with 65.9 % of capacity retention at 0.5 A g−1 after 200 cycles. Thus, such honeycomb-like amorphous carbon-encapsulated Si nanoparticles/graphene composite anode is highly promising for practical next-generation LIBs.

Enhanced lithium storage in pomegranate-like carbon via dual confinement of lithiophilic seeds and Li deposition

The uncontrollable dendrite growth and infinite volume expansion of Li during cycling lead to low Coulombic efficiency (CE) and short cycling life, severely impeding the commercial progress of lithium metal batteries (LMBs). In this work, nitrogen-doped carbon nanospheres (CSs) with ultrafine lithiophilic ZnO nanoparticles encapsulated by interconnected pomegranate-like carbon sheets (denoted as ZnO@NPCS) have been designed and constructed to serve as novel lithium hosts. The ultrafine ZnO nanoparticles uniformly distributed in the CSs can significantly reduce the Li nucleation barrier, while the well-designed pomegranate-like carbon sheets within the CSs can provide continuous and fast electron/ion transport channels, accelerating the Li+ transfer kinetics. Moreover, the internal interconnected carbon networks can confine the lithiophilic nanoparticles, preventing them from detaching or aggregating during cycling, and meanwhile offer individual voids to accommodate deposited Li. Thus, both lithiophilic seeds and deposited Li can be well confined in the pomegranate-like structure. Such a dual-confinement effect enables the ZnO@NPCS electrode to exhibit ultralong cycling life for more than 1000 cycles with ultrahigh CE (>99.5 %) without Li dendrites growth, which is further validated by in-situ transmission electron microscopy and phase-field simulations. Therefore, this dual-confinement strategy provides an inspiring insight to design superior Li hosts for developing superior LMBs and can be extended to other battery systems.

Enabling high-performance lithium iron phosphate cathodes through an interconnected carbon network for practical and high-energy lithium-ion batteries

The olivine lithium iron phosphate (LFP) cathode has gained significant utilization in commercial lithium-ion batteries (LIBs) with graphite anodes. However, the actual capacity and rate performance of LFP still require further enhancement when combined with high-capacity anodes, such as silicon (Si) anodes, to achieve high-energy LIBs. In this study, we introduce a gelatin-derived carbon network into a nanosized LFP cathode without the need for additional binding and conductive agents, employing a simple and cost-effective method. The resulting cathode exhibits an extremely high LFP content (∼92.3 wt%), enabling it to show a high real capacity of 159.7 mAh/g at 0.2 C in half cells. Additionally, the interconnected carbon network effectively facilitates electron and Li+ transport, providing rapid pathways within the LFP nanoparticles. Consequently, the cathode exhibits superior rate capability (107.3 mAh/g at 10 C) and good cycling performance (with a capacity retention of ∼ 80 % after 500 cycles). To further assess its practical viability, the LFP cathode is assembled into a full cell utilizing a Si-based anode with a N/P ratio of 1.1. The resulting full cell delivers a significantly high energy density of 419.7 Wh kg−1, coupled with prolonged cycle life, highlighting its promising prospects for practical applications.

Direct Induction of Porous Graphene from Mechanically Strong and Waterproof Biopaper for On-Chip Multifunctional Flexible Electronics.

Graphene with a 3D porous structure is directly laser-induced on lignocellulosic biopaper under ambient conditions and is further explored for multifunctional biomass-based flexible electronics. The mechanically strong, flexible, and waterproof biopaper is fabricated by surface-functionalizing cellulose with lignin-based epoxy acrylate (LBEA). This composite biopaper shows as high as a threefold increase in tensile strength and excellent waterproofing compared with pure cellulose one. Direct laser writing (DLW) rapidly induces porous graphene from the biopaper in a single step. The porous graphene shows an interconnected carbon network, well-defined graphene domains, and high electrical conductivity (e.g., ≈3Ω per square), which can be tuned by lignin precursors and loadings as well as lasing conditions. The biopaper in situ embedded with porous graphene is facilely fabricated into flexible electronics for on-chip and paper-based applications. The biopaper-based electronic devices, including the all-solid-state planer supercapacitor, electrochemical and strain biosensors, and Joule heater, show great performances. This study demonstrates the facile, versatile, and low-cost fabrication of multifunctional graphene-based electronics from lignocellulose-based biopaper.

Interconnected N-doped carbon network as high-performance anode material for superior lithium ion hybrid capacitor

Interconnected N-doped carbon network as high-performance anode material for superior lithium ion hybrid capacitor

Single Cu atoms confined in N-doped porous carbon networks by flash nanocomplexation as efficient trifunctional electrocatalysts for Zn-air batteries and water splitting

Constructing efficient trifunctional single-atom electrocatalysts is exceedingly alluring and challenging for enhancing the efficiency of water splitting and Zn-air batteries (ZABs). Herein, a novel N-doped porous carbon network (SC-CuSA-NC) catalyst with Cu single atoms is constructed via flash nanocomplexation (FNC) technology and a double-network gel-limiting strategy. The novelty of this method lies in the combination of physical confinement and chemical confinement by FNC, which enables uniform spatial isolation and atomic-level dispersion of Cu atoms in the hydrogel, effectively inhibits the migration of Cu during synthesis, and achieves accurate and controllable preparation of Cu single atoms catalyst. Benefiting from the highly active Cu–N4 sites and distinct interconnected three-dimensional porous carbon network, SC-CuSA-NC shows superior ORR/OER/HER performance. Significantly, the ZAB assembled by SC-CuSA-NC displays a high specific capacity (775.0 mAh g−1) and could effectively drive water splitting (1.58 V at 10 mA cm−2). This work expands the synthesis method of single-atom catalysts and provides a new approach for the accurate and controllable synthesis of electrocatalysts for water splitting and ZABs.

3D interconnected honeycomb-like ginkgo nut-derived porous carbon decorated with β-cyclodextrin for ultrasensitive detection of methyl parathion

A novel and economical approach was proposed for synthesizing the β-cyclodextrin (β-CD) embellished ginkgo nut-derived porous carbon (GNDPC) with three-dimensional (3D) interconnected honeycomb-like morphology, which was employed to decorate the glassy carbon electrode (GCE) for the construction of methyl parathion (MP) electrochemical sensor (GNDPC@β-CD/GCE) for the first time. GNDPC with higher surface area possessed good adsorptive capacity and superior conductive property because of 3D interconnected honeycomb-like porous carbon network. β-CD improved the dispersibility of GNDPC and enhanced the molecular recognition and accumulation capability of GNDPC towards MP. The synergetic cooperation of β-CD and GNDPC realized the ultrasensitive detection property of MP (Limit of detection: 4.52 nM; Concentration: 0.005–15 μM). The constructed GNDPC@ β-CD/GCE displayed good MP determination feasibility in apple and pear juices (Recovery rate: 95.8–100.1%; Relative standard deviation: 2.12–4.17). This work exhibits a novel approach for the sensitive determination of MP in foods.

A natural juncus-derived three-dimensional interconnected tubular carbon network decorated with tiny solid-solution metal sulfide nanoparticles achieves efficient sodium storage

Juncus-derived three-dimensional interconnected tubular carbon network decorated with tiny solid-solution metal sulfide nanoparticles favorably affords affluent active sites and porous channels, thus endowing superior sodium-storage performance.

Dual-template synthesis of interconnected 3D hollow N-doped carbon network for electrochemical application

Dual-template synthesis of interconnected 3D hollow N-doped carbon network for electrochemical application

Dense T-Nb2O5/Carbon Microspheres for Ultrafast-(Dis)charge and High-Loading Lithium-Ion Batteries.

Orthorhombic niobium pentoxide (T-Nb2O5) is regarded as a potential anode material for lithium-ion batteries (LIBs) due to ultrafast charge/discharge and high safety. However, the poor electronic conductivity and low mass loading of nanostructured T-Nb2O5 limit its practical application in LIBs. Herein, we design and construct dense microspheres consisting of nanostructured T-Nb2O5 embedded in amorphous N-doped carbon (Nb2O5@NC) via a facile method to achieve fast ionic and electronic transport as well as a high mass loading. The dense micro-sized particles with an interconnected carbon network avoid the low mass loading and volumetric energy density of conventional nanostructures. Interconnected pores in the range of a few nanometers are also formed in the Nb2O5@NC microspheres. Notably, at a high mass loading of 12.8 mg cm-2, Nb2O5@NC can achieve a high specific capacity of 171.5 mAh g-1 and an areal capacity of 2.05 mAh cm-2, showing its high lithium storage capacity. The intercalation reaction mechanism with a small volume change during cycling at both crystal lattice and microsphere levels is confirmed by in situ X-ray diffraction and in situ high-resolution transmission electron microscopy. The elegant structure and the electrochemical reaction mechanism disclosed in the work is important for designing ultrafast-(dis)charge electrode materials.

Carboxylated graphene oxide nanosheets as efficient electrodes for high-performance supercapacitors.

In the presence of dry ice, a series of graphitic materials with carboxylated edges (ECGs) were synthesized by ball milling graphite for varied times (24, 36, and 46 h). The influence of carboxylation on the physiochemical characteristics and electrochemical performance as effective electrodes for supercapacitors were assessed and compared with pure graphite. Several characterization techniques were employed to investigate into the morphology, texture, microstructure, and modification of the materials. Due to its interconnected micro-mesoporous carbon network, which is vital for fast charge-discharge at high current densities, storing static charges, facilitating electrolyte transport and diffusion, and having excellent rate performance, the ECG-46 electrode among the investigated samples achieved the highest specific capacitance of 223 F g−1 at 0.25 A g−1 current density and an outstanding cycle stability, with capacitance retention of 90.8% for up to 10,000 cycles. Furthermore, the symmetric supercapacitor device based on the ECG-46 showed a high energy density of 19.20 W h kg−1 at 450.00 W kg−1 power density. With these unique features, ball milling of graphitic material in dry ice represents a promising approach to realize porous graphitic material with oxygen functionalities as active electrodes.

An interconnected and scalable hollow Si-C nanospheres/graphite composite for high-performance lithium-ion batteries

Silicon (Si) anode is the most promising alternative for next generation lithium-ion batteries (LIBs) owing to large theoretical capacity, low working voltage and abundant natural resources. However, tremendous volume change of Si during the (de)lithiation processes causes repetitive formation of solid electrolyte interphase (SEI) layers, loss of electrical contact and electrodes pulverization, limiting its commercial application. Herein, we fabricate an interconnected hollow Si-C nanospheres/graphite composite via a facile and scalable approach. Notably, hollow Si-C nanospheres and graphite are homogeneously combined by using the surfactants as surface modifiers of graphite and introducing carbon dioxide (CO2) into magnesiothermic reduction reaction, resulting in the enhanced compatibility between hollow Si-C nanospheres and graphite, and the well-established electrical conductive network. The resultant Si-C nanospheres/graphite composite anode with carbon content of 59 wt% delivers a large reversible specific capacity of 662 mAh g−1 and a high capacity retention of 65.7% at 0.5 A g−1 after 200 cycles. Such excellent rate performance and superior cycling performance are attributed to high electrical conductivity and buffering effect of graphite, superior compatibility between hollow Si-C spheres and graphite, uniform distribution of both Si-C nanospheres with a unique hollow architecture and graphite flakes inside the composites and well-established interconnected electrical conductive carbon networks, which can effectively alleviate Si volume expansion and maintain good electrical contact during cycling. This strategy provides insights into designing Si-based anodes for practical LIBs.

Two Birds with One Stone: A NaCl-Assisted Strategy toward MoTe2 Nanosheets Nanoconfined in 3D Porous Carbon Network for Sodium-Ion Battery Anode

The larger van der Waals interlayer distance of MoTe2 is favorable for Na+ insertion/extraction when MoTe2 is used as sodium-ion battery (SIB) anode. However, engineering of stoichiometric 2D MoTe2 and high-conductivity carbon networks with robust interfacial bonding for SIB anodes is still a great challenge and rarely reported. In this work, high-crystallized 2D MoTe2 nanosheets nanoconfined by interconnected 3D porous carbon networks (indicated with 2D-MoTe2@3DPCN) for SIB anode is successfully constructed via a facile NaCl-assisted strategy. During the synthesis process, the NaCl demonstrates the two birds with one stone effect: the template effect for the formation of interconnected 3D hierarchical porous carbon networks, and the promoting effect of chalcogen atom exchange for in situ conversion from 2D-MoS2 to 2D-MoTe2, which was validated by both experimental results and first-principles simulations. The as-constructed unique architecture not only facilitates both ions and electrons transportation and diffusion throughout the overall electrode, but also can effectively prevent the aggregation of MoTe2 nanosheets and buffer their volume change during the insertion and extraction of Na+. As a result, 2D-MoTe2@3DPCN as SIB anode displays high reversible discharge specific capacity (∼412 mA h g−1 at 100 mA g−1), excellent rate capability (213.8 mA h g−1 at 20 A g−1) and outstanding long cycle life even at high charge/discharge current density (the capacity retention after 3000 cycles is 77.4% at 20 A g−1). This work provides a new path to construct MoTe2-based composites for application in energy-storage fields and beyond.

Biomass-Derived Graphene-Based Materials Embedded with Onion-Like Carbons for High Power Supercapacitors

We report a facile method to produce composites of hierarchically porous graphene-based materials embedded with onion-like carbons (Gr-OLCs) for high power density supercapacitors. Gr-OLCs were produced from the mixture of glucose, thiourea, and ammonium chloride, through stepwise reactions including a condensation reaction, subsequent blow into three-dimensional (3D) structure, and carbonization process. Owing to its high surface area, hierarchical pore distribution, and interconnected carbon networks embedded with onion-like carbons, this carbon showed high specific capacitance of 140 F g−1 even at a high current density of 64 A g−1. Interconnected carbon networks and hierarchical pore structrues served to facilitate the movement of electrolyte ions within the electrode and provide an efficient pathway for the movement of charge carriers, resulting in an exceptionally high power density of 1,737 kW kg−1 with an energy density of 30 Wh kg−1 at current density of 256 A g−1. Studies on the complex capacitance revealed that a supercapacitor with these carbon electrodes exhibited stable energy storage features with minimal capacitive loss, achieving both high power and energy densities. This work provides a new type of carbon-based electrode materials that can meet the requirements for high power energy storage devices.

Interconnected 3D carbon network with enhanced reaction kinetics and architecture stability for advanced potassium-ion hybrid capacitors.

Due to their high energy/power densities and ultralong cycle lifespan, potassium-ion hybrid capacitors (PIHCs) have attracted increasing research interest for large-scale energy storage systems. However, the kinetics mismatch between the battery-type anodes and capacitor-type cathodes severely hampers the further development of PIHCs. Herein, the kinetics-enhanced N-doped amorphous porous carbon with an interconnected three-dimensional (3D) network (marked as NPC) is reported. The existence of an amorphous configuration can provide numerous storage potassium sites, while the interconnected 3D network contributes to electron transfer, thus improving the reversible capacity and reaction kinetics of NPC. The expanded carbon interlayer spacing, well-established porous structure and plentiful active sites induced by N-doping greatly boost the structural stability and further increase kinetics. Benefiting from these structure merits, the NPC electrode delivers a high capacity (257.7 mA h g-1 at 0.5 A g-1), an excellent rate capability (199.5 mA h g-1 at 2 A g-1), and an extraordinary cycling stability over 3000 cycles at 2 A g-1. Moreover, coupling with activated carbon (AC) cathode and NPC anode, the assembled PIHCs exhibit ultra-large energy/ultra-high power density (177.3 W h kg-1 and 19348.3 W kg-1) with a long cycling life (81.6% capacity retention after 3000 cycles).