Ultrafast Rate Capability Research Articles

Nanoscale Parallel Circuitry Based on Interpenetrating Conductive Assembly for Flexible and High‐Power Zinc Ion Battery

AbstractHigh‐rate capability has become an important feature for energy storage devices, but it is often accompanied with a significant reduction in energy density. Therefore, developing an energy storage technology that combines high‐rate capability with high energy density is a great challenge for next‐generation electronic devices. Here, parallel circuitry is constructed at the nanoscale to lower the resistance for ion and electron transport that largely determines the rate performance. The parallel circuitry is constructed through intertwining continuous carbon nanotubes with an interpenetrating conductive assembly based on hierarchically layered MXene (Ti3C2Tx ) functionalized by KMnO4 (MnOx @Ti3C2Tx ). The assembly shows ultrafast rate capability, e.g., maintaining 50% capacity when the current density increases from 0.1 to 10 A g−1. Investigations of the kinetics and charge storage mechanisms confirm the efficiency of the designed parallel circuitry in improving rate capability by providing rapid pathways for ions and electrons, as well as dividing the current flow evenly into individual MnOx @Ti3C2Tx flakes in the assembly. The flexible MnOx @Ti3C2Tx based electrode endows zinc ion batteries with outstanding mechanical robustness and good power delivering performance. The paradigm presented here paves a new way for designing electrodes with high‐rate capability toward next‐generation energy storage technologies.

Hierarchical Hollow‐Microsphere Metal–Selenide@Carbon Composites with Rational Surface Engineering for Advanced Sodium Storage

AbstractAs a result of its high‐energy density, metal–selenides have demanded attention as a potential energy‐storage material. But they suffer from volume expansion, dissolved poly‐selenides and sluggish kinetics. Herein, utilizing' thermal selenization via the Kirkendall effect, microspheres of NiSe2 confined by carbon are successfully obtained from the self‐assembly of Ni‐precursor/PPy. The derived hierarchical hollow architecture increases the active defects for sodium storage, while the existing double N‐doped carbon layers significantly alleviate the volume swelling. As a result, it shows ultrafast rate capability, delivering a stable capacity of 374 mAh g−1, even after 3000 loops at 10.0 A g−1. These remarkable results may be ascribed to the NiOC bonds on the interface of NiSe2 and the carbon film, which leads to the faster transfer of ions, the effective trapping of poly‐selenide, and the highly reversible conversion reaction. The kinetic analysis of cyclic voltammetry (CV) demonstrates that the electrochemical process is mainly dominated by pseudocapacitive behaviors. Supported by the results of electrochemical impedance spectroscopy (EIS), it is confirmed that the solid–electrolyte interface films are reversibly formed/decomposed during cycling. Given this, this elaborate work might open up a potential avenue for the rational design of metal‐sulfur/selenide anodes for advanced battery systems.

Strategy for Boosting Li-Ion Current in Silicon Nanoparticles

Improvement in the rate capability needs to be addressed for utilization of a Si anode in high-power Li-ion batteries. Regarding the rate capability, its improvement by Si–C nanocomposites seems to be somewhat saturated, thus indicating that the other method should be tried for further enhancement of the rate capability. Here, we introduce Si nanoparticles uniformly coated with nanometer-thick polyacrylonitrile (PAN) with better wettability to liquid electrolytes and minimizing electronic resistance, which might result from a thick PAN coating: the effective contact surface area made by the contact of Si nanoparticles and liquid electrolyte is increased for larger Li-ion current, leading to ultrafast rate capability retaining 62% of the 0.2C rate discharge capacity at 100C. In addition, a strong adhesive property of PAN provides highly mechanically robust Si anodes for multielectrode-stacked flexible lithium-ion batteries, which show no physical damage after 30 000 bending cycles with a bending radius of ...

Construction of 3D architectures with Ni(HCO3)2 nanocubes wrapped by reduced graphene oxide for LIBs: ultrahigh capacity, ultrafast rate capability and ultralong cycle stability.

Rechargeable lithium-ion batteries (LIBs) have been the dominating technology for electric vehicles (EV) and grid storage in the current era, but they are still extensively demanded to further improve energy density, power density, and cycle life. Herein, a novel 3D layered nanoarchitecture network of Ni(HCO3)2/rGO composites with highly uniform Ni(HCO3)2 nanocubes (average diameter of 100 ± 20 nm) wrapped in rGO films is facilely fabricated by a one-step hydrothermal self-assembly process based on the electrostatic interaction and coordination principle. Benefiting from the synergistic effects, the Ni(HCO3)2/rGO electrode delivers an ultrahigh capacity (2450 mA h g-1 at 0.1 A g-1), ultrafast rate capability and ultralong cycling stability (1535 mA h g-1 for the 1000th cycle at 5 A g-1, 803 mA h g-1 for the 2000th cycle at 10 A g-1). The detailed electrochemical reaction mechanism investigated by in situ XRD further indicates that the 3D architecture of Ni(HCO3)2/rGO not only provides a good conductivity network and has a confinement effect on the rGO films, but also benefits from the reversible transfer from LiHCO3 to Li x C2 (x = 0-2), further oxidation of nickel, and the formation of a stable/durable solid electrolyte interface (SEI) film (LiF and LiOH), which are responsible for the excellent storage performance of the Li-ions. This work could shed light on the design of high-capacity and low-cost anode materials for high energy storage in LIBs to meet the critical demands of EV and mobile information technology devices.

In-situ self-polymerization restriction to form core-shell LiFePO4/C nanocomposite with ultrafast rate capability for high-power Li-ion batteries

Charging and discharging lithium ion batteries (LIBs) in a matter of seconds to tens of seconds rather than hours can potentially lead to technological breakthroughs and bring about lifestyle changes. This work aims to enable ultrafast Li-ions charge/discharge ability for LIBs by significantly accelerating the diffusion kinetics of Li+ ions and enhancing the electric conductivity in LiFePO4 cathode material. An innovative method was developed to synthesize LiFePO4/C nanocomposite with secondary particles structure containing uniform (20–50nm) and highly crystalline LiFePO4 single nanoparticles which are free from any anti-site defects (e.g. Fe·Li) and uniformly coated by a highly graphitized carbon-shell network with good electronic conduction. The LiFePO4/C material was formed from a FePO4·xH2O/poly(furfuryl alcohol) nanocomposite, which was prepared through a self-regulated in situ polymerization restriction method, followed by a rapid wet-chemistry lithiation (H+/Li+ ion exchange) and subsequent calcination. Benefiting from the ultra-small size of the LiFePO4 nanoparticles, absence of Fe·Li defects, and a continuous 3D carbon network, the LiFePO4/C nanocomposite demonstrated ultrafast lithium-storage rates when used as a cathode material in lithium half-cells, which required only 21.6s to reach a complete discharge at a rate of 150C while still maintaining a high specific capacity of 95.4 mAh g−1.

Synthesis of hierarchical porous TiNb2O7 nanotubes with controllable porosity and their application in high power Li-ion batteries

TiNb2O7 nanotubes with a hierarchical porous structure show ultra-fast rate capability at an extremely high rate of 50C.

Ultrafast charge/discharge solid-state thin-film supercapacitors via regulating the microstructure of transition-metal-oxide

A transition-metal-oxide-based asymmetric supercapacitor shows ultrafast rate capability and fast frequency response through regulating the microstructure of a vertical porous Fe2O3nanowall electrode.

Comments on “Geometry and fast diffusion of AlCl4 cluster intercalated in graphite [Electrochim. Acta 195 (2016) 158–165

We report that the planar AlCl4 clusters in graphite reported in [Electrochim. Acta 195 (2016) 158-165] are not justified from the point of view of theory and their fast diffusion in graphite has nothing to do with the ultrafast rate capability of Al-ion battery in experiments.

3D Hierarchical Anode Configuration Composed of Ultralong N-Doped Graphene Scrolls-Wrapped MnO Nanowires for High-Performance Li-Ion Batteries

Transition metal oxides (TMOs) have been touted as one of the most promising anode materials for next generation lithium ion batteries (LIBs). Yet, how to build energetic TMOs-based electrode architectures by addressing the structural and interfacial stability issues facing TMOs anodes still remains a big challenge. Here, we design and fabricate a novel 3D hierarchical anode configuration composed of ultralong porous MnO nanowires (NWs) wrapped within nitrogen-doped graphene scrolls (GSC) which themselves interlinked and embedded in continuous interconnected networks of nitrogen-doped graphene ribbons (GR). Such a hybrid material (namely, MnO@N-GSC/GR) with plenty of internal void space is totally in an ordered 3D hierarchical porous architecture by taking the advantage of multi-scale and multi-dimensional integration of nanoscaled MnO and graphene building blocks, which can address all the issues related to MnO dissolution, conversion, aggregation and volumetric expansion during the Li+ insertion/extraction. As a result, the 3D hierarchical MnO@N-GSC/GR serves high-performance anode materials for LIBs with a very high reversible specific capacity (as high as 765 mAh g-1 at even 1000 mA g-1) and ultrafast rate capability (349 and 201 mAh g-1 at 8000 and 15000 mA g-1, respectively), as well as excellent discharge and charge capabilities (rapidly charged to 86.7% and 79.9% in 10.5 and 4.6 min, respectively, using the constant current mode). Most importantly, such the robust MnO@N-GSC/GR electrode shows no capacity fading even after 1000 cycles at a high current density of 2000 mA g-1, and no morphology change. The as-built 3D hierarchical MnO@N-GSC/GR is the most efficient MnO-based anode materials ever reported for LIBs.

Heteroepitaxy-Induced Rutile VO2 with Abundantly Exposed (002) Facets for High Lithium Electroactivity

Research on VO2 cathodes for lithium ion batteries has been mainly focused on the VO2 (B) phase. However, rutile VO2 (M/R) has rarely been studied because of the intrinsically low lithium activity resulting from the highly anisotropic nature of lithium accommodation. Here, we demonstrate that heteroepitaxial engineering can be an effective strategy for activating the anisotropic electrode and developing kinetically superior electrodes. Appropriate lattice mismatch between the active material (VO2) and conductive support (Sb:SnO2) yields a coherent interface, where tensile strain aids preferential growth along the rutile c-axis as well as expansion in the ab plane and thereby the exposure of reactive (002) facets. The VO2–Sb:SnO2 electrode exhibits high reversible capacity (350 mA h g–1 at 100 mA g–1) and ultrafast rate capability (196 mA h g–1 at 2000 mA g–1) with structural stability, which represents record-high performance compared with previous VO2 reports, including those on other polymorphs such as ...

Solid-state electric double layer capacitors for ac line-filtering

Ultra-fast solid electric double layer capacitors (EDLCs) have been developed in both sandwich and planar interdigitated configurations using vertically-oriented graphene nanosheet (VOGN) electrodes with a hydroxide ion-conducting tetraethylammonium hydroxide (TEAOH)–polyvinyl alcohol (PVA) polymer electrolyte. These solid-state EDLCs could be scanned at a rate of 1000Vs−1 in cyclic voltammetry and demonstrated response times of less than 1ms. They retained high performance over 18 months of shelf storage and after 100,000 charge/discharge cycles with limited packaging, demonstrating the high stability of TEAOH–PVA electrolyte. The solid-state capacitors are capable of performing at elevated temperatures and have demonstrated a response time of 0.35ms at 90°C. Given their ultra-fast rate capability, excellent shelf-life and cycle life, and excellent temperature stability, these solid-state EDLCs are promising smaller and lighter alternatives to the bulky electrolytic capacitors now used for ac line-filtering.

Ultrahigh Capacity Due to Multi-Electron Conversion Reaction in Reduced Graphene Oxide-Wrapped MoO2 Porous Nanobelts.

Multivalent transition metal oxides (MOx ) containing redox centers which can theoretically accept more than one electron have been suggested as promising anode materials for high-performance lithium ion batteries (LIBs). The Li-storage mechanism of these oxides is suggested to involve an unusual conversion reaction leading to the formation of metallic nanograins and Li2 O; however, a full-scale conversion reaction is seldom observed in molybdenum dioxide (MoO2 ) at room temperature due to slow kinetics. Herein, a full-scale multi-electron conversion reaction, leading to a high reversible capacity (974 mA h g(-1) charging capacity at 60 mA g(-1) ) in LIBs, is realized in a hybrid consisting of reduced graphene oxide (rGO) sheet-wrapped MoO2 porous nanobelts (rGO/MoO2 NBs). The rGO wrapping layers stabilize the nanophase transition in MoO2 and alleviate volume swing effects during lithiation/delithiation processes. This enables the hybrid to exhibit great cycle stability (tested to around 1900 cycles) and ultrafast rate capability (tested up to 50 A g(-1) ).

Surfactant-assisted mild solvothermal synthesis of nanostructured LiFePO4/C cathodes evidencing ultrafast rate capability

A surfactant-assisted solvothermal synthesis is hereby applied to produce carbon-coated LiFePO4/C nanostructured Li-ion battery cathodes. The use of different mixed alcohol/water solutions for the dissolution of a cationic surfactant is absolutely peculiar in this field and herewith exploited to tailor-make the properties of the active material particles (e.g., morphology and electrochemical behaviour). Thorough investigation is carried out by means of X-ray powder diffraction, scanning and transmission electron microscopy, cyclic voltammetry and constant current charge-discharge cycling. The best performing sample, obtained in a 20:80 w/w ethanol:water solution, demonstrates good specific capacity values, high Coulombic efficiency and rate capability, with stable behaviour upon long-term cycling even at ultrafast 100C discharge regime. This is definitely remarkable for a nanosized powder specifically conceived for high power applications obtained by means of low cost raw materials, simple and reliable procedures.

NaCrO2 cathode for high-rate sodium-ion batteries

Carbon-coated NaCrO2 synthesized via an emulsion method exhibits excellent cyclability and ultrafast rate capability up to a rate of 150 C, demonstrating ideal properties for advanced sodium-ion batteries.

Porous TiNb2O7 nanofibers decorated with conductive Ti1−xNbxN bumps as a high power anode material for Li-ion batteries

Porous TiNb2O7 nanofibers with metal nitride bumps show ultra-fast rate capability even at 100 C.