Sodium-ion Capacitors Research Articles

Design of kinetic well-matched Mo2C nanoparticles anchored into 3D hierarchical porous carbon towards high-rate sodium ion storage

Sodium ion capacitors (SICs) have attracted considerable attentions since it is integrating the complementary features of both high energy and power densities. One of the most crucial tasks for develop highly efficient SICs is to increase the faradaic Na+ redox kinetics from the battery-type anode to match the electrical double-layer capacitance-type cathode. In this work, Mo2C nanoparticles uniformly anchored into cross-linked hierarchical porous carbon (HPC-Mo2C) have been produced by a water-soluble NaCl template strategy. The as-obtained HPC-Mo2C composite shows a large specific surface area of 385.6 m2 g−1 with well distributed micro–meso–macropores structure, delivering a superior rate capability (108.2 mAh g−1 at 5 A g−1) and robust long-term cycling of 190.6 mAh g−1 at 1 A g−1 after 2500 cycles. Electrochemical measurements illustrate that the Mo2C nanoparticles uniformly anchored into cross-linked hierarchical porous structure can accelerate fast Na+ diffusion kinetics toward excellent rate capacity and increase the pseudocapacitive behavior for the redox reaction. The SIC composed of HPC-Mo2C as anode and activated carbon (AC) as cathode delivers an impressive energy density of 130.2 Wh kg−1 and ultra-high power density of 30,000.0 W kg−1, as well as an unprecedented cycling stability of 88.9% retention after 10,000 cycles with a potential range of 0–4.0 V. This work may cater to the requirements for rationale kinetic matching electrode for the advanced SICs.

Advanced Carbon Materials for Sodium‐Ion Capacitors

AbstractNonaqueous sodium‐ion capacitors (SICs), as a new type of energy storage cell, can potentially achieve high energy‐power densities, long cycling lifespan, and low cost in one device. Given this, developing suitable carbonaceous electrode materials for carbon‐based SICs is of great significance. Unlike lithium‐ion batteries (LIBs) and lithium‐ion capacitors (LICs) that have been successfully commercialized, SICs are still at an early stage. As a result, rational electrode material design for SICs is needed to meet the requirements of electrochemical energy‐storage systems. Carbon materials with a wide range of sources and low toxicity deliver significant potential applications in high‐performance SICs, whether as positive or negative parts. Various carbonaceous electrode materials have been explored and investigated for developing SICs over the past years. This Review firstly introduces the classical and widely used configurations and corresponding energy‐storage mechanism in detail for SICs. Then, recent progress on carbonaceous electrode materials, including cathode and anode materials, are summarized. Finally, the challenges and some suggestions on the future development of carbon‐based SICs are proposed.

Flexible MoSe2/MXene films for Li/Na-ion hybrid capacitors

MoSe2 presents a prospect in sodium-ion capacitors (SICs) and lithium-ion capacitors (LICs), which are considered as promising new energy systems because they possess the merits of both batteries and supercapacitors. In this work, we develop a flexible and free-standing MoSe2/MXene film with sandwich structure as an anode for SICs and LICs. The highly conductive MXene sheets can boost the electrochemical activity of MoSe2 nanoparticles. Meanwhile, the MoSe2 nanoparticles can also enlarge the interlayer spacing of MXene film, facilitating the permeation of electrolyte and eventually leading to fast reaction kinetics of MoSe2. The sandwich structure can effectively limit the loss of intermediate products generated during the insertion/extraction reactions of MoSe2, giving rise to a durable cycle performance. The MoSe2/MXene film with an optimized mass ratio exhibits much improved Li/Na storage performances as compared with the pristine MoSe2, particular the long term cyclic stability. SICs and LICs could deliver high energy/power densities (Max 110.1 Wh kg−1/4764.7 W kg−1 and 84.9 Wh kg−1/3288.3 W kg−1, respectively), as well as long lifespans, demonstrating the prospective of such MXene/MoSe2 film electrode towards alkali metal ion capacitors. Assembled flexible SICs/LICs prototypes further prove the potential application for the future flexible energy storage devices.

Sulfur and nitrogen dual-doped carbon nanofiber with enlarged interlayer distance as a superior anode material for sodium-ion capacitors

Sodium-ion capacitors (SICs) have attracted widespread attention due to their combination of high-energy batteries and high-power supercapacitors as well as low cost of sodium resources. However, the anodes exhibit low specific capacities and sluggish kinetics, thus limiting fast development of high-performance SICs. In the present work, the sulfur and nitrogen dual-doped carbon nanofiber (S-NCNF) membrane was synthesized as a novel anode material of SICs. Introduction of S atoms can result in an enlarged interlayer distance of 0.38 nm in S-NCNF, which is beneficial to Na+ ion insertion and the electron transport. As a result, the obtained S-NCNF electrode shows high sodium-storage capacity (298 mAh g−1 at 0.1 A g−1) and superior rate capability (188 mAh g−1 at 5 A g−1). The fabricated SIC delivers high energy density (97 Wh kg−1) and power density (17 kW kg−1) as well as long cycle life (3000 cycles).

High-Energy and High-Power Pseudocapacitor–Battery Hybrid Sodium-Ion Capacitor with Na+ Intercalation Pseudocapacitance Anode

HighlightsLayered iron vanadate ultrathin nanosheets (FeVO UNSs) with a thickness of ~ 2.2 nm were synthesized by a sonicate-assisted method.Pseudocapacitive Na+ intercalation of FeVO UNSs anode delivers high initial coulombic efficiency (93.86%), high reversible capacity (292 mAh g−1), excellent rate capability, and remarkable cycling stability.A pseudocapacitor–battery hybrid SIC is assembled with the elimination of presodiation and delivers high energy and power densities.

Ti2Nb2O9/graphene hybrid anode with superior rate capability for high-energy-density sodium-ion capacitors

Ti2Nb2O9/reduced graphene oxide (Ti2Nb2O9/RGO) hybrid anode is fabricated by flocculation of HTiNbO5 nanosheets and graphene oxide (GO) nanosheets, followed by annealing HTiNbO5/GO composite at 500 °C in Ar for 1 h, in which HTiNbO5 nanosheets are prepared by ion-exchange and followed by exfoliating process using KTiNbO5 as precursor. HTiNbO5 nanosheets are topotactically transformed into Ti2Nb2O9 nanosheets and GO is reduced into RGO by calcining the HTiNbO5/GO composite, causing enhanced Na+-intercalation pseudocapacitive behavior and significantly improved conductivity for Ti2Nb2O9/RGO hybrid anode. Ti2Nb2O9/RGO hybrid anode delivers superior rate capability (206 mAh g−1 at 4 A g−1) and excellent cycling performance with 95% capacity retention at 1 A g−1 over 1000 cycles. A hybrid device is assembled using Ti2Nb2O9/RGO as the anode and activated carbon (AC) as the cathode, it shows a maximum high energy density of 96 Wh kg−1 at a power density of 75 W kg−1, and the energy density still maintains 39 Wh kg−1 when the power density achieves as high as 10029 W kg−1. Moreover, the assembled device displays good cycling stability with a capacity retention of 79% after 10,000 cycles. This work can provide new insights on fabrication of Ti-Nb oxides-graphene based composite anode for sodium ion capacitors.

Collaborative compromise of two-dimensional materials in sodium ion capacitors: mechanisms and designing strategies

This review provides a comprehensive summary of the research progress of emerging 2D materials in sodium ion capacitors.

Dual-carbon Na-ion capacitors: progress and future prospects

Dual-carbon-based sodium-ion capacitors (DC-NIC) engage carbonaceous electrodes as anode and cathode. High power and energy densities make it a suitable candidate for EV applications with capability to provide clean, green, and cost-effective energy.

A novel zinc sulfide impregnated carbon composite derived from zeolitic imidazolate framework-8 for sodium-ion hybrid solid-state flexible capacitors.

The pyrolysis of metal–organic frameworks (MOFs) is an easy approach to prepare metal oxides as well as nanoporous carbon with high specific surface area. In the present work, for the first time, ZIF-8 (zeolitic imidazolate framework-8) has been pyrolyzed under different conditions to derive two products, i.e., highly porous carbon (C) and zinc sulfide (ZnS) infused carbon (ZnS@C). These two materials, i.e., nanoporous C and ZnS@C, have been investigated as a negative and a positive electrode, respectively, for potential application in a hybrid asymmetrical solid-state supercapacitor device (HASD). The controlled pyrolysis approach for the preparation of ZnS@C has yielded uniformly distributed ZnS nanoparticles inside the carbon structure. A 1.8 V HASD has been assembled, which delivered an excellent energy density of 38.3 W h kg−1 (power density of 0.92 kW kg−1) along with the greatly desirable feature of cycling stability. The proposed selection of materials as electrodes is promising to develop futuristic hybrid capacitors.

Coupling anodic/cathodic energy storage through in situ heterostructure regulation of ordered microporous carbon for sodium-ion hybrid capacitors

Two types of ordered microporous carbon are obtained through in situ heterostructure regulation and can realize anodic/cathodic energy storage. The assembled sodium-ion hybrid capacitor achieves high energy and power densities.

Natural template derived porous carbon nanoplate architectures with tunable pore configuration for a full-carbon sodium-ion capacitor

Porous carbon nanoplates with tailored morphology were fabricated as electrodes of SIC by using natural dolomite as a template and coal tar as a carbon precursor. The full-carbon SIC exhibits high energy and power densities as well as a long cycling lifespan.

A carbon-based material with a hierarchical structure and intrinsic heteroatom sites for sodium-ion storage with ultrahigh rate and capacity.

The storage of sodium ions with carbon materials has huge potential for large-scale application due to its resource-rich and environmental advantages. However, how to realize high power density, high energy density and long cycle life are the bottlenecks restricting its development. Herein, by using a facile synthesis strategy, a carbon-based framework with a hierarchical structure and intrinsic heteroatom sites which are the characteristics contributing to ultrahigh rate and capacity has been achieved. As a result, the hierarchical carbon-based material exhibits excellent performance when used as both the anode and cathode for sodium-ion capacitors (SICs), which can deliver a high energy density of 224 W h kg-1 (at 180 W kg-1), an ultrahigh power density of 17 160 W kg-1 (at 128 W h kg-1) and ultralong cycle life (91% capacity retention after 10 000 cycles at 2 A g-1), outperforming most of the previously reported SICs with other configurations.

Rational Design of Three-Dimensional Interlaced Frameworks with 2D Mxene-Ti <sub>3</sub>C <sub>2</sub>T <sub>x</sub> and 2D ZnCo Bimetallic Hydroxide for Enhanced Sodium-Ion Capacitors

Rational Design of Three-Dimensional Interlaced Frameworks with 2D Mxene-Ti <sub>3</sub>C <sub>2</sub>T <sub>x</sub> and 2D ZnCo Bimetallic Hydroxide for Enhanced Sodium-Ion Capacitors

Interface Inversion: A Promising Strategy to Configure Ultrafine Nanoparticles over Graphene for Fast Sodium Storage.

Due to the merits of high activity and rapid reaction kinetics, ultrafine nanoparticles loaded on conductive scaffolds are of great potential in energy-related fields. Usually, the nucleation and uniform growth of these active nanoparticles in high density on scaffolds is governed by the local ion concentration gradient and nucleation sites at the interfaces. On account of this, a novel interface-inverting strategy is developed to modulate the diffusion of metal ions toward the nucleation sites, leading to the tuned growth of ultrafine nanoparticles anchored on graphene. Typically, the Ni(OH)2 deposited on graphene initially enables the interface inverting from oil-water-solid consisting of liquid paraffin (LP), water, and GO to water-oil-solid, finally resulting in LP-enveloped Ni(OH)2 /GO structure. In response, the inert-infiltrated LP layer inhibits the solubility and diffusion of nickel ions, which functions to modulate the growth and aggregation of adjacent nanoparticles. As a demonstration, the phosphorized Ni2 P@C/G as anode in sodium-ion capacitor can deliver a high energy density of 54Wh kg-1 at a high power density of 23kW kg-1 yet with a remarkable rate performance due to the surface-enhanced energy storage and fast Na+ transport enabled by the tuned surface/interface.

Kinetic-matching between electrodes and electrolyte enabling solid-state sodium-ion capacitors with improved voltage output and ultra-long cyclability

Broader context: A kinetic-matched bilayer ionogel electrolyte and an ultra-high kinetic anode were proposed to overcome the kinetic imbalance in solid-state sodium-ion capacitors. The COMSOL Multiphysics simulation proved that as-formed asymmetrical ionogel electrolyte could efficiently weaken the concentration gradient up to 0.3 M at 5 A g −1 and relieve polarization. A sodium-ion capacitor exhibited high energy density of 94.8 Wh kg −1 at 1925.0 W kg -1 and ultra-long-term ability of 10,000 cycles within 4.0 V owing to the double kinetic-matchings design. • A new kinetic-matched design was proposed for solid-state sodium-ion capacitors. • An ultra-high kinetic anode was fabricated via a “Phase Engineering” route. • A COMSOL simulation verified the function of the asymmetric ionogel electrolyte. • The kinetic-balanced sodium-ion capacitor exhibited high stability of 10,000 cycles. Sodium-ion capacitors (SICs) are attracting extensive attentions owing to their high energy density and the availability of abundant sodium element. However, kinetic imbalance between cathodes and anodes or between electrodes and electrolytes at interfaces originating from different ions storage mechanisms need to be well minimized. Thus, it is significant to design specific ion-matching enabled electrodes and electrolytes. Here, an ultra-high kinetic TiO 2 (A)/TiO 2 (B)@C/CNT nanohybrid electrode with rich textured interfaces and a capacity of 251 mAh g −1 was fabricated via a “Phase Engineering” route. In particular, the effects induced by cubic and monoclinic phases were distinguished by an In-situ XRD technique. Moreover, a bi-layered ternary ionogel electrolyte was constructed to achieve optimal kinetic balance and ion matching. Impressively, the optimized bilayer solid electrolyte exhibited an ionic conductivity of 5.22 × 10 -3 S cm −1 and a high Na + transference number of ~ 0.611, resulting to a weakened concentration gradient of 0.3 M at 5 A g −1 and enhanced intercalation/deintercalation of Na + at the anode/electrolyte interface. The enhanced kinetic matching was verified by a COMSOL Multiphysics simulation. Significantly, the double-kinetic-matching design on both electrodes and electrolyte rendered a sodium-ion capacitor (SIC) with an energy density of 94.8 Wh kg −1 at 1925.0 W kg −1 and an ultra-long cyclability of 10,000 cycles at an effective operating potential of 4.0 V. This work demonstrates an effective strategy to high performance solid-state sodium-ion capacitors via the synergistic optimization of electrodes and electrolyte and highlights the importance of understanding the kinetic matching.

Aligned Arrays of Na2Ti3O7 Nanobelts and Nanowires on Carbon Nanofiber as High‐Rate and Long‐Cycling Anodes for Sodium‐Ion Hybrid Capacitors

Sodium‐ion capacitors (SICs) have attracted extensive attentions due to their integration of high‐energy battery and high‐power capacitor as well as the naturally abundant sodium resource. A major challenge of current SICs is to achieve high rate performance and long‐cycle stability of the battery‐type anode. Herein, fast sodium storage is achieved from sodium titanate (Na2Ti3O7) arrays that are uniformly grown on highly conductive carbon nanofiber networks with a high mass loading of 5.6 mg cm−2. Nanowires and nanobelts of Na2Ti3O7 are both synthesized, and their Na‐ion storage properties are compared. Both arrays can be used as binder‐free and flexible electrodes, but the nanobelts exhibit higher specific capacity and better rate performance than the nanowires with similar mass loading. The difference between two types of nanostructures is ascribed to their different kinetics in ion/charge transport, according to the electrochemical impedance data. SIC full devices consisting of the Na2Ti3O7 nanobelt anode and biomass‐derived porous carbon cathode are constructed, which show pretty high specific energy and power performance.

(Invited) New Brands of High Energy Electrochemical Capacitors with Hybridized Carbon Electrodes

The main disadvantages of electrical double-layer capacitors – EDLCs, are the relatively low amount of energy stored and the high cost of the devices. For new applications, as powering of e.g., electric vehicles, the concept of hybrid capacitor (HC) appears as a promising approach enabling to enhance the energy output. HCs behave as EDLC (e.g., linear galvanostatic charge/discharge, rectangular cyclic voltammogram, low time constant), while combining capacitive and battery-like electrodes. Since the battery-type electrode operates in a narrow potential range, the potential excursion of the EDL electrode is almost twice larger than in a symmetric EDLC, leading to approximately doubling of the discharge capacitance [1]. Hence, for the same voltage range, the specific energy of the HC is twice higher than for an EDLC. In the last decade, HCs using a redox active electrolyte such as the iodine/iodide system [2] and lithium-ion capacitors (LIC) [3] have emerged as very promising technologies, essentially owing to the fact that carbon electrodes are highly conductive and relatively inexpensive.LICs implement a lithiated graphite negative electrode operating ca 100 mV above the lithium deposition potential and an activated carbon positive electrode using a wide potential range, allowing the charge storage capacity to be approximately doubled, while the maximum cell voltage can reach 4 V. Hence, the specific energy of a LIC is around 4 to 5 times higher than in an EDLC using the same AC at comparable specific power. However, as it is mandatory to pre-intercalate lithium in the negative graphite electrode before operating a LIC, it has been proposed to include an auxiliary metallic lithium electrode [4], what complicates the cell construction, while excess lithium might cause also safety issues. Therefore, we have recently implemented a new strategy based on a sacrificial lithiated material (for example 3,4-dihydroxybenzonitrile dilithium salt – Li2DHBN [5]) added in the positive AC electrode, and from which lithium is irreversibly extracted and intercalated in the graphite anode. In case of Li2DHBN, we have demonstrated that the DOBN oxidized derivative is soluble in the electrolyte, leaving only AC at the positive electrode after lithium extraction. At 1 kW kg-1, the specific energy of the LIC reaches 50 Wh kg-1 against only 12 Wh kg-1 for the EDLC built with the same AC. We will show that this concept can be extended to high performance and low cost sodium-ion capacitors [6].For AC-based hybrid capacitors realized by the implementation of redox active electrolytes, aqueous solutions of iodides have lately prevailed over others, owing to well-separated EDL and battery-like charging mechanisms [1]. However, as the voltage of AC/AC cells with alkali iodides is limited to only 0.8-1.2 V [2], we have proposed to use bi-functional aqueous electrolytes including the redox component (e.g., KI) and a supporting neutral electrolyte (e.g., Li2SO4), enabling to extend the potential range of the negative electrode. The capacitance of the HC is doubled as compared to a typical EDLC, whereas the voltage can reach 1.5 – 1.6 V [7]. Recently, an AC/AC cell based on a mixture of choline iodide and choline nitrate demonstrated the same energy and power performance as a commercial EDLC using an organic electrolyte, while being able to perform down to -40°C [8].Acknowledgements: The Foundation for Polish Science is acknowledged for financially supporting the HYCAP project (research grant TEAM TECH/2016-3/17).References B. Gorska, E. Frackowiak, F. Beguin, Curr. Opin. Electrochem. 9 (2018) 95.G Lota, E. Frackowiak , Electrochem. Comm. 11 (2009) 87.T. Aida, K. Yamada, M. Morita, Electrochem. Solid State Lett. 9 (2006) A534.T. Aida, I. Murayama, K. Yamada, M. Morita, Electrochem. Solid State Lett. 10 (2007) A93.P. Jezowski, O. Crosnier, E. Deunf, P. Poizot, F. Beguin, T. Brousse, Nat. Mater. 17 (2018) 167.X. Pan, A. Chojnacka, P. Jezowski, F. Beguin, Electrochim. Acta 318 (2019) 471.Q. Abbas, P. Babuchowska, E. Frackowiak, F. Beguin, J. Power Sources 326 (2016) 652.P. Przygocki, Q. Abbas, B. Gorska, F. Beguin, J. Power Sources 427 (2019) 283.

Boosting Capacitive Sodium-Ion Storage in Electrochemically Exfoliated Graphite for Sodium-Ion Capacitors.

Sodium (Na)-ion capacitors possess higher energy density than supercapacitors and higher power density than Na-ion batteries. However, kinetic mismatches between fast capacitive charge storage on the cathode and sluggish battery-type reactions on the anode lead to a poor charge/discharge rate capability and insufficient power output of Na-ion capacitors. Thus, developing suitable anode materials for Na-ion capacitors is urgently desirable. This work demonstrates an electrochemically exfoliated graphite (EEG) anode with enhanced capacitive charge storage, greatly boosting the Na-ion reaction kinetics of co-intercalation. The EEG anode shows a high reversible capacity of 109 mAh g-1 and maintains a good capacity retention of 90% after 1000 cycles. The assembled Na-ion capacitor using the EEG anode can finish the charge/discharge process in less than 10 s, which achieves an ultrahigh power density of 17,500 W kg-1 with an energy density of 17 Wh kg-1. The high capacitive contributions at both the anode and cathode contribute to the fast rate capability and high power output of the fabricated Na-ion capacitors. This work will promote the development of ultrafast charging sodium-ion storage devices.

2D Sandwiched Nano Heterostructures Endow MoSe2 /TiO2- x /Graphene with High Rate and Durability for Sodium Ion Capacitor and Its Solid Electrolyte Interphase Dependent Sodiation/Desodiation Mechanism.

Nano heterostructures relying on their versatile construction and the breadth of combined functionality have shown great potential in energy storage fields. Herein, 2D sandwiched MoSe2 /TiO2- x /graphene nano heterostructures are designed by integrating structural and functional effects of each component, aiming to address the rate capability and cyclic stability of MoSe2 for sodium ion capacitors (SICs). These 2D nano heterostructures based on graphene platform can facilitate the interfacial electron transport, giving rise to fast reaction kinetics. Meanwhile, the 2D open structure induces a large extent of surface capacitive contribution, eventually leading to a high rate capability (415.2mAhg-1 @ 5Ag-1 ). An ultrathin oxygen deficient TiO2- x layer sandwiched in these nano heterostructures provides a strong chemical-anchoring regarding the products generated during the sodiation/desodiation process, securing the entire cyclic stability. The associated sodiation/desodiation mechanism is revealed by operando and ex situ characterizations, which exhibits a strong solid electrolyte interphase (SEI) dependence. The simulations verify the dependent sodiation products and enhanced heterostructural chemical-anchoring. Assembled SICs based on these nano heterostructures anode exhibit high initial Coulombic efficiency, energy/power densities, and long cycle life, shedding new light on the design of nano heterostructure electrodes for high performance energy storage application.

Self-Supported NaTi2(PO4)3 Nanorod Arrays: Balancing Na+ and Electron Kinetics via Optimized Carbon Coating for High-Power Sodium-Ion Capacitor.

The NaTi2(PO4)3 (NTP) anode materials exhibit high Na+ diffusion dynamics; carbon-based materials can effectively improve its limited electronic conductivity. However, the low Na+ diffusion of NTP/C composite materials from inhomogeneous carbon mixing or uncontrollable carbon coating cannot keep up with fast electron transfer, leading to undesirable electrochemical performances. Herein, a uniform and controllable carbon layer is designed on the self-supported-coated NTP nanorod arrays with binder-free (NTP@C NR) to improve Na+ and electron kinetics simultaneously. As a result, the NTP@C NR electrodes possess initial coulombic efficiency (ICE = 97%), good rate capabilities (89.1 mA h g-1 at 100 C), and stability with ≈78.4% of capacity retention rate at even 30 C over 1200 cycles. The sodium-ion capacitors with NTP@C NR as an anode and commercially activated carbon as a cathode exhibit ∼9180.0 W kg-1 of power density at 10 A g-1 and super high retention of ≈94.5% at 1 A g-1 over 7000 cycles. This work will help balance transport kinetics between the ion and electron for materials applied in storage devices.