Ultrahigh Rate Capability Research Articles

Hierarchical ZnCo2O4-ZnO/ZnCo2O4 core-shell microarchitecture as pseudocapacitive material with ultra-high rate capability and enhanced cyclic stability for asymmetric supercapacitors

Compared with materials for electric double layer capacitors, pseudocapacitive electrode materials have the disadvantage of poor cyclic stability, which is expected to be improved via reasonably designing material microarchitecture. In this work, the hierarchical ZnCo2O4-ZnO/ZnCo2O4 core–shell microarchitecture composite was constructed directly on Ni foam by a two-step solvothermal pathway and calcination. In particular, by growing porous ZnCo2O4 nanosheets on the surface of ZnCo2O4-ZnO microsphere, the pseudocapacitance was significantly enhanced. In addition, this superior configuration provided a stable space structure and highly exposed surface/interface with abundant electrochemical reaction sites, to ensure both the long-term cyclic stability and the diffusion and transfer of electrolyte ions in fast redox kinetics. Consequently, the as-prepared pseudocapacitive material possessed a high specific capacity (2487F g−1 at 1 A g−1), ultrahigh rate capability of 2110F g−1 at 20 A g−1, striking pseudocapacitance contribution (∼95% at 1.0 mV s−1), and ultra-long cycle stability (6000 cycles with 93.3% of capacitance retention). Furthermore, the assembled aqueous asymmetric supercapacitor demonstrated a high energy density of 55.46 W h kg−1 at 1500 W kg−1. The overall results offered a promising approach for rationally designing pseudocapacitive electrode materials with abundant surface/interface active sites for high-performance supercapacitors.

Additive‐Free Ultrastable Hydrated Vanadium Oxide Sol/Carbon Nanotube Ink for Durable and High‐Power Aqueous Zinc‐Ion Battery

AbstractAqueous zinc‐ion batteries (ZIBs) based on near‐neutral electrolytes represent a promising large‐scale energy storage solution for a deeper and broader penetration of clean renewable energy. The preparation of electrode paste is vital for the normal performance and stability of ZIBs. Herein, the authors report an additive‐free V2O5·1.6H2O (h‐V2O5)/carbon nanotube (CNT) hybrid ink to prepare large‐scale free‐standing h‐V2O5/CNT film for high‐rate and durable ZIBs. The as‐prepared h‐V2O5/CNT film exhibits a high specific capacity of 446.4 mA h g−1 (volumetric capacity of 839.2 mA h cm−3) at 0.2 A g−1 when used as cathode for ZIBs. It retains considerable capacities of 202.3 and 139.0 mA h g−1 even at high current densities of 20 and 50 A g−1, respectively, exhibiting ultrahigh rate capability. The assembled cell also displays outstanding long‐term cycling stability with a remarkable capacity of 309.7 mA h g−1 even after 3500 cycles at 10 A g−1. More importantly, this h‐V2O5 sol can serve as a general “surfactant” to disperse a variety of nanomaterials in water. This work proposes a facile strategy to prepare additive‐free paste for conductive electrode, which holds great potential for a broad range of applications.

Natural ore molybdenite as a high-capacity and cheap anode material for advanced lithium-ion capacitors

Hybrid lithium-ion capacitors (LICs) receive special interests because they work by combining the merits of high-capacity lithium-ion batteries and high-rate capacitors in a Li salt containing electrolyte, so as to bridge the gap between the two devices. One of main challenges for LICs is to develop inexpensive and superior anode materials at high rates. In this work, natural molybdenite was utilized as precursor to achieve the scalable production of cheap MoS2/carbon composites. This molybdenite-derived MoS2/carbon electrode can not only exhibit excellent Li+-storage performances including ultrahigh specific capacity (1427 mAh g–1 after 1000 cycles at 1 A g–1) and rate capability (554 mAh g–1 at 10 A g–1), but also possess four-times higher tap density than that of commercial graphite. By employing MoS2/carbon as the anode and activated carbon as the cathode, the as-assembled LIC device delivers both high energy//high power density and long cycle lifespan. Furthermore, the price is nearly 200 orders of magnitude lower than the traditional high-purity chemicals, which can be easily scaled up to achieve high-throughput production.

Homogeneous hybridization of NASICON-type cathode for enhanced sodium-ion storage

Na3V2(PO4)3 has attracted intensive interest as cathode materials of sodium-ion batteries (SIBs), whereas, its performance is hindered by the sluggish Na-ion diffusion. Herein, with delicate reaction-component regulation and ideal paired Na7V4(P2O7)4PO4, homogeneous hybridized Na3V2(PO4)3-based cathode (denoted as HNVP) is designed to fully unleash the biphase synergy and trigger the ultra-fast kinetics in the SIBs. The dynamics of HNVP can be largely motivated by the intimate interaction via homogeneous hybridized Na3V2(PO4)3 and Na7V4(P2O7)4PO4, the intermediate state of Na7V4(P2O7)4PO4 and the in-situ constructed expressway of amorphous crystal boundaries, all of which enable ultra-high rate capability up to 50C and applicable area loading of 48.85 mg cm−2; while the reinforced structural of HNVP enables record-low capacity decay of 0.0051% per cycle over 2100 cycles. Moreover, under the guidance of phase diagrams, the homogeneous hybridization strategy can be further promoted to various types of advanced composite cathodes for intrinsic innovations.

An interface-free integrative graphitic carbon network film with defective and S/O-Codoped hollow units for voltage-stable, Ultra-fast and long-life potassium ion storage

• An interface-free integrative graphitic carbon network film (IGCN) was prepared. • Lattice defects and large layer distance of IGCN formed by Ar/S/H plasma etching. • The ED-IGCN exhibits high rate durable cyclability with obvious discharge plateau. • The pseudo-capacitive mechanism and contributed a lot to the fast K-storage kinetics. In the K-storage process, graphitic carbon exhibits unique practical plateau potential but suffers terrible rate and cycle performance, because its perfect long-range ordered carbon structure, small lattice space and high contact/interface resistance are still bottlenecks to limit the kinetics and structural stability. Herein, we prepare a novel interface-free integrative graphitic carbon network film on a large scale, and enlarged its lattice distance and reasonably introduce defects (ED-IGCN) to boost kinetics and cyclability via a plasma-enhanced etching/S-doping process. Typically, the ED-IGCN entails ultra-thin hollow graphitic units (diameter ∼ 10 nm, shell wall ∼ 1 nm) interconnected by sp2 hybrid covalent bonds, providing an interface-free highly conductive network. Additionally, the defective long-range ordered carbon arrangement and enlarged lattice distance ensured numerous open channels and shortened pathways with low diffusion barrier for boosting the fast (de)potassiation kinetics. When applied in PIB, the ED-IGCN anodes delivered a high reversible capacity of 408 mAh g −1 at 20 mA g −1 , and ultra-high rate and long-term cyclability without expensing its unique discharge plateau. The capacity maintained up to 91.1 mA h g −1 after 10,000 cycles at 5 A g −1 with a capacity retention of ∼ 60% (∼51% after 11,000 cycles), which is not inferior to that of any graphitic carbon reported previously. We separated the diffusive capacity, and pseudo-/double-layer capacitive contributions, and verified that the plasma treating process enhanced the capacitive K-storage mechanism which give great contribution to the fast kinetics. A full-cell based on potassium Prussian blue (KPB) cathode and ED-IGCN anode delivered an initial reversible capacity of 177 mAh g −1 at 1000 mA g −1 , and retained ∼ 70% after 50 cycles, further demonstrating the ultra-high rate capability of ED-IGCN in practical application. The results provide new insights into the design and structure regulations of graphitic carbon for fast-charging batteries with stable working voltages and an understanding of the diffusion acceleration mechanism in graphitic carbon materials.

Metastable V2O3 embedded in 2D N-doped carbon facilitates ion transport for stable and ultrafast sodium-ion storage

V2O3 is a promising candidate for sodium-ion batteries (SIBs) anode. Compared with common rhombohedral V2O3, cubic V2O3 is a unique metastable phase with ordered oxygen vacancies and high energy state, but lacks study in the field of electrochemical energy storage. Herein, a metastable cubic V2O3 embedded in N-doped carbon nanosheets (c-V2O3@NC) is synthesized by a simple molten salt method with urea assisted. Ab initio molecular dynamics calculations demonstrate that cubic V2O3 possesses reduced Na+ diffusion activation energy. Benefiting from the novel metastable structure and multiple modifications, the c-V2O3@NC shows enhanced ion diffusion kinetics, robust structure and improved conductivity. As a consequence, the c-V2O3@NC exhibits high specific capacity, ultralong cycle life and ultrahigh rate capability (274 mAh g−1 even after 3000 cycles at 5 A g−1) as anode material for SIBs. This work shows a feasible synthesis and synchronous modification for metastable materials to electrical energy storage applications.

Uniquely Designed Tungsten Oxide Nanopetal Decorated Electropsun PAN Nanofiber for a Flexible Supercapacitor with Ultrahigh Rate Capability and Cyclability

Uniquely Designed Tungsten Oxide Nanopetal Decorated Electropsun PAN Nanofiber for a Flexible Supercapacitor with Ultrahigh Rate Capability and Cyclability

Conformal surface-nanocoating strategy to boost high-performance film cathodes for flexible zinc-ion batteries as an amphibious soft robot

To satisfy the increasing power demand for the rapid development of wearable and portable electronics, the design of quasi-solid-state aqueous zinc-ion batteries (QAZIBs) requires the advancement of flexible electrodes possessing excellent electrochemical performance and extraordinary mechanical strength. This purpose could be realized by utilizing electrospinning to obtain flexible film cathodes composed of layer-structured transition metal dichalcogenides@nitrogen-doped carbon nanofibers (TMD@N-CNFs), attributed to the synergetic effect between the nanostructured TMDs (for capacity) and interwoven 1D N-CNFs (for flexibility). However, their potentials are seriously impeded by the dissolution and structural instability of active materials during zinc-ion (de)intercalation process, leading to insufficient rate capability and much-shortened cycle life. Herein, to address this big challenge, we have demonstrated the approach of developing an ultrathin Al2O3 coating layer by atomic-layer-deposition (ALD) to greatly boost the electrochemical performance of vanadium diselenide nanosheets@N-CNFs (Al2O3@VSe2 NSs@N-CNFs) film cathode in flexible QAZIBs. Moreover, the ALD-Al2O3 nanocoating provides desperately necessary mechanical robustness in the cross-2D nanosheet direction of VSe2 standing on the N-CNFs surface, as confirmed by finite element simulation results. Consequently, the QAZIB delivers an outstanding stack energy density of ∼125 Wh kg−1, an ultrahigh rate capability of 65.2% capacity retention after 200-fold increase in current density and an excellent cycling performance of 86.2% retention after 2500 cycles. Finally, we integrate the flexible QAZIB into a soft inchworm robot, which achieves reversible actuation both on land and in water and keeps good electrochemical stability, showing the prospective potentials of introducing energy storage devices for soft robotics with broad multifunctional applications.

Plasma-promoted surface regulation of a novel integrative carbon network for boosting the long-cycle capability of sodium-ion storage

In the process of Na+-storage in hard carbon materials, the sluggish (de)sodiation kinetics and irreversible reactions of surface groups with electrolytes are bottlenecks that limit the rate performance and long-term cycle stability. We successfully prepared a novel integrative carbon network material (ICN) on a large scale, and the carbon structure and surface oxygen groups were regulated to increase the rate and cycle capability using a plasma-assisted catalyst-free carbonization process. ICNs typically have ultrathin carbon nanofiber units (∼10 nm) interconnected by sp2 hybrid covalent bonds, which form an interface-free integrative conductive network and ultra-short ion/electron transport pathways. The order degree of surface carbon stacking, interlayer spacing, and the content of –CO groups can be regulated by surface plasma treating to further boost kinetics and enhance reversible reactions. Thus, the ICN exhibits all-round improvements in terms of a large reversible capacity (389.5 mAh g−1 after 100 cycles at 50 mA g−1), a superior rate capability (285 mAh g−1 at 2000 mA g−1 after 3000 cycles), and good cycling stability (retain 72.2% after 10,000 cycles at 2000 mA g−1). According to the analysis of the dynamics, the capacitive mechanism by which Na+ quickly inserts/adsorbs with the surface/subsurface atoms is primarily responsible for the excellent electrochemical performance. A full cell made up of an ICN anode and a Na3V2(PO4)3 cathode successfully lit the diode, demonstrating the ultra-high rate capability of ICN in practical application. It has a reversible capacity of 101.9 mAh g−1 at 1000 mA g−1 and maintains 76% after 2000 cycles, demonstrating the ultra-high rate capability of ICN in practical application. These results suggest a new perspective on the structure design of carbon-based materials for fast and long-life sodium-storage anodes.

Ultrathin Si Nanosheets Dispersed in Graphene Matrix Enable Stable Interface and High Rate Capability of Anode for Lithium‐ion Batteries

AbstractOwing to the thinness and large lateral size, 2D Si materials exhibit very promising prospects as the high‐performance anodes of lithium‐ion batteries (LIBs). However, the facile synthesis of ultrathin 2D Si nanosheets (Si‐NSs) and their efficient application still remain a great challenge. Herein, the fabrication of ultrathin Si‐NSs with the average thickness of <2 nm is demonstrated using a unique etching‐reduction protocol. After hybridizing with graphene, the as‐prepared Si‐NSs@rGO material delivers ultrahigh rate capability (2395.8 mAh g−1 at 0.05 A g−1 and 1727.3 mAh g−1 at 10 A g−1), long cycling lifespan (1000 cycles at 2 A g−1 with a capacity decay rate of 0.05% per cycle) and high average Coulombic efficiency (99.85% during 1000 cycles). The superior performance is attributed to the ultrathinness of Si‐NSs that greatly improves the diffusivity and reversibility of Li+ ions. This work provides a strategy for fabricating a high‐rate‐capability anode material to meet the growing demand for high power density LIBs.

Dual-directional electronic modulation of manganese oxides enabled by heterostructures for efficient sodium ion storage

Heterostructures of manganese oxides (MnOx, i.e., MnO and Mn3O4) with carbon nitride (CN@MnOx) are prepared to boost the Na + storage capability of MnOx. Two different interfacial electric fields originated from the electronic redistribution at the interfaces of CN@MnO and CN@Mn3O4 endow CN@MnOx with high reversible capacity of 305 F g−1 at 1 A g−1, ultrahigh rate capability of 223 F g−1 at 20 A g−1, and exceptional long-term cycling lifespan without significant capacity decay up to 5000 cycles at 1 A g−1. An asymmetric supercapacitor based on CN@MnOx electrode materials delivers a high energy density of 46.7 Wh kg−1 at a power density of 1000 W kg−1. Mechanism studies showed that the enhanced sodium ion storage performance in CN@MnOx is attributed to a dual-directional electronic modulation of MnOx, which simultaneously improve the electronic conductivity and accelerate the Na+ transfer kinetics. This work opens up a unique strategy to regulate the electronic structure of multi-phase electrode materials, and meanwhile provides new clues for the energy storage mechanism in multi-phase electrode materials.

Coordination polymer-derived Al3+-doped V2O3/C with rich oxygen vacancies for an advanced aqueous zinc-ion battery with ultrahigh rate capability

Coordination polymer-derived Al3+-doped V2O3/C with rich oxygen vacancies exhibits excellent rate performance and long-term cycling durability in a zinc-ion battery. The doping of Al3+ can decrease the binding energy and diffusion barrier of Zn2+.

Amorphous Ni-Co Binary Hydroxide Nanospheres with Super-Long Cycle Life and Ultrahigh Rate Capability as Asymmetric Supercapacitors

Amorphous Ni-Co Binary Hydroxide Nanospheres with Super-Long Cycle Life and Ultrahigh Rate Capability as Asymmetric Supercapacitors

Ultrastable hydrated vanadium dioxide cathodes for high-performance aqueous zinc ion batteries with H+/Zn2+ Co-insertion mechanism

The ultrastable VO2·xH2O nanobelt with crystal water has been prepared successfully by a simple and easy large-scale hydrothermal method as cathode materials for aqueous zinc-ion batteries with ultra-high reversible capacity and rate capability.

Co-substitution in a Prussian blue analog with a hollow heterostructure for ultrahigh capacity and rate capability aqueous Zn2+ batteries.

Nickel and manganese co-substitution into hollow Prussian blue nanocubes (H-PBMN) has been successfully carried out via utilizing a high-concentration polymer template to grow manganese-Prussian blue (PBM) and nickel-Prussian blue (PBN) through a slow nucleation process. Due to the hollow structure and double metal co-substitution, the properties of the electrode material have been optimized, and it presents an ultrahigh capacity of 138.4 mA h g-1 at 0.05 A g-1.

Metallic 1T-MoS2 coupled with MXene towards ultra-high rate-capabilities for supercapacitors

A schematic diagram showing the synthesis of the 1T-MoS2/Ti3C2Tx heterostructure and the fast charge–discharge networks in the heterostructure.

Reconstructing Vanadium Oxide with Anisotropic Pathways for a Durable and Fast Aqueous K-Ion Battery.

Aqueous potassium-ion batteries are long-term pursued, due to their excellent performance and intrinsic superiority in safe, low-cost storage for portable and grid-scale applications. However, the notorious issues of K-ion battery chemistry are the inferior cycling stability and poor rate performance, due to the inevitably destabilization of the crystal structure caused by K-ions with pronouncedly large ionic radius. Here, we resolve such issues by reconstructing commercial vanadium oxide (α-V2O5) into the bronze form, i.e., δ-K0.5V2O5 (KVO) nanobelts, as cathode materials with layered structure of enlarged space and anisotropic pathways for K-ion storage. Specifically, it can deliver a high capacity as 116 mAh g-1 at the 1 C-rate, an outstanding rate capacity of 65 mAh g-1 at 50 C, and a robust cyclic stability with 88.2% capacity retention after 1,000 cycles at 1 C. When coupled with organic anode in a full-cell configuration, the KVO electrodes can output 95 mAh g-1 at 1 C and cyclic stability with 77.3% capacity retention after 20,000 cycles at 10 C. According to experimental and calculational results, the ultradurable cyclic performance is assigned to the robust structural reversibility of the KVO electrode, and the ultrahigh-rate capability is attributed to the anisotropic pathways with improved electrical conductivity in KVO nanobelts. In addition, applying a 22 M KCF3SO3 water-in-salt electrolyte can impede the dissolving issues of the KVO electrode and further stabilize the battery cyclic performance. Lastly, the as-designed AKIBs can operate with superior low-temperature adaptivity even at -30 °C. Overall, the KVO electrode can serve as a paradigm toward developing more suitable electrode materials for high-performance AKIBs.

Natural Lepidolite Enables Fast Polysulfide Redox for High‐Rate Lithium Sulfur Batteries

AbstractLithium sulfur (Li–S) batteries possess energy capacities well beyond those of current Li‐ion technologies, but are plagued by severe diffusion loss of sulfur intermediates and sluggish sulfur reduction kinetics. Here, the design is reported of a lepidolite‐modified polypropylene (C‐Lepidolite@PP) separator to suppress polysulfide shuttling and accelerate the transformation of polysulfides. Because the electrons of S atoms transfer to the 3p antibonding orbits of Si atoms, lepidolite effectively confines polysulfides by forming strong Si–S bonds to weaken the S–S bonds of polysulfides. The ultralow lithium‐ion diffusion barrier (0.081 eV) of lepidolite allows for free lithium‐ion migration and thus significantly facilitates polysulfide conversion from liquid Li2S8 to solid Li2S to enable fast polysulfide redox for high‐rate current operation. With the C‐Lepidolite@PP design, Li–S batteries deliver an ultrahigh rate capability of 703 mAh g−1 at 7 C and a high areal capacity of 7.53 mAh cm−2 with a sulfur loading of 6.5 mg cm−2. Moreover, the 15‐d self‐discharge rate is reduced by ≈85% with the C‐Lepidolite@PP separator, which provides promise for the practical use of Li–S batteries.

Metal-organic frameworks derived anatase/rutile heterostructures with enhanced reaction kinetics for lithium and sodium storage

Heterostructured electrodes with interfacial effects have exhibited great potential in improving the electrochemical kinetic of electrode materials. Herein, to accelerate the sluggish kinetic of TiO2 electrodes in lithium ion batteries (LIBs) and sodium ion batteries (SIBs), anatase–rutile heterostructure with affluent surface/bulk oxygen vacancies was fabricated via an in-situ topological conversion strategy. The abundant surface/bulk oxygen vacancies, enhanced electronic conductivity and regulated C-N bonds accelerated the electronic/ionic transport and improved the pseudo-capacitive behaviors of the heterostructured electrode. Theoretical calculation corroborated that the introduction of anatase–rutile heterostructure favored the close connection between TiO2 and carbon layers, heightened the electronic conductivity of the composites and lowered the migration energy barriers of Li+ and Na+. Deservedly, TRA electrode with abundant anatase–rutile heterostructures delivered a ultrahigh rate capability of 334.9 mAh g−1 in LIBs under an expanded potential range (3–0.05 V vs. Li/Li+) and a competitive reversible capability of 223.0 mAh g−1 in SIBs at 3.36 A g−1. This work not only revealed the migration/transformation process of Ti, O, C and N elements during the calcination of metal–organic framework, but also provided new insights into the charge storage mechanism of anatase–rutile heterostructure.

Superhydrophilicity and ultrahigh-rate supercapacitor performances enabled by mesoporous carbon doped with conjugated hydroxyl

The use of carbon-based nanostructures as electrode for supercapacitor usually suffers from poor rate capability mainly due to their inherent hydrophobic character that leads to large diffusion resistance for aqueous electrolyte. It is envisaged that the construction of hydrophilic carbon by introducing electrochemically active groups can increase the capacitance and rate capability of a supercapacitor. Herein, by a simple approach of adopting CaCO3 as template, we fabricated a mesoporous carbon with worm-like mesoporosity, open-access morphology, and excellent hydrophilicity. The carbon material is enriched with electrochemically active oxygen groups (8.8 atom%) in the forms of conjugated carbonyl (-C=O) and hydroxyl (-C-OH). The hydroxyl on the surface could react with alkaline electrolyte forming hydroxy negative ions that enhance the surface polarity and hydrophilicity of carbon. Due to synergistic effect of these favorable factors, the derived mesoporous carbon (CaCs) materials demonstrate superior supercapacitor performances including large capacitance of 305 F/g, ultrahigh rate capability of 75.7% at current density of 1.0 to 100 A/g, large specific energy of 27.1 Wh/kg@1000 W/kg (maintaining 19.1 Wh/kg@18,800 W/kg), displaying great potential as electrode in the fields of electrochemical energy storage.