Exceptional Rate Performance Research Articles

A Low Strain A‐Site Deficient Perovskite Lithium Lanthanum Niobate Anode for Superior Li+ Storage

AbstractThe oxide perovskite family holds great promise for diverse applications on account of their unique chemical and physical properties. However, owing to the inadequate Li+‐storage sites, the insertion‐type perovskite anodes for lithium‐ion batteries (LIBs) are limited. A‐site deficient perovskites with rich intrinsic vacancies and ion transport channels are believed to be the desirable hosts of superior Li+ storage. Herein, the perovskite Li0.1La0.3NbO3 (LLNO) is designed and demonstrated as the remarkable anode for LIBs with a high specific capacity, a safe operating voltage, an excellent rate performance, and a long cycling life. More importantly, the outstanding cycling stability of LLNO is originated from its low strain characteristic with a maximum volume change of only 1.17%. The exceptional rate performance can be explained by the unconventional Li+ transport pathways with external → grain boundaries → lattice deficiencies. These results not only reveal that A‐site deficient perovskite LLNO is a promising anode for LIBs but also provide fundamental insights into the Li+ ions transport mechanism, facilitating the development of high‐performance perovskite anodes.

Freestanding trimetallic Fe–Co–Ni phosphide nanosheet arrays as an advanced electrode for high‐performance asymmetric supercapacitors

Transition metal phosphides hold great promise for high performance battery-type electrode materials due to their superb electrical conductivity and high theoretical capacity. Unfortunately, the electrochemical properties of single metal or bimetallic phosphides are unsatisfactory owing to their low energy density and poor cyclic stability, and one feasible approach is to introduce heteroatoms to form trimetallic phosphides. Here, novel Fe–Co–Ni–P nanosheet arrays are in situ synthesized on a flexible carbon cloth substrate via an electrodeposition method followed by a phosphorization treatment. Due to the presence of abundant redox active sites, large specific surface area with mesoporous channels, desirable electrical conductivity, modified electronic structure, and synergistic effect of Fe, Co, and Ni ions, the as-prepared Fe–Co–Ni–P electrode displays significantly enhanced electrochemical performance when compared to bimetallic phosphides Fe–Co–P and Fe–Ni–P. Remarkably, the Fe–Co–Ni–P electrode exhibits a large specific capacity of 593.0 C g−1 at 1 A g−1, exceptional rate performance (80.3% capacity retention at 20 A g−1), and good cycling stability (84.2% capacity retention after 5000cycles). Besides, an asymmetric supercapacitor device with Fe–Co–Ni–P electrode as a positive electrode and a hierarchical porous carbon as a negative electrode shows a high energy density of 57.1 Wh kg−1 at a power density of 768.5 W kg−1 as well as excellent cyclability with 88.4% of initial capacity after 10,000cycles. This work manifests that the construction of trimetallic phosphides is an effective strategy to solve the shortcomings of single or bimetallic phosphides for high-performance supercapacitors.

Template‐Sacrificed Hot Fusion Construction and Nanoseed Modification of 3D Porous Copper Nanoscaffold Host for Stable‐Cycling Lithium Metal Anodes

AbstractLithium (Li) metal anodes have been proposed as a promising candidate for high‐energy‐density electrode materials in secondary batteries. However, the dendrite growth and unstable electrode–electrolyte interfaces during Li plating/stripping are fatal to their practical applications. Herein, the construction of 3D porous Au/Cu nanoscaffold prepared via a convenient template‐sacrificed hot fusion construction method and a nanoseed modification process as an effective Li metal hosting material are proposed. The Au/Cu nanoscaffold can spatially guide uniform deposition of Li metal free from the growth of Li dendrites due to the homogenous Li+ ion flux and negligible nucleation overpotential. Moreover, the Cu skeleton can relieve volume change and stabilize local current density during cycling processes. Benefiting from these advantages, the symmetric cells based on self‐supported Li‐filled Au/Cu (Li‐Au/Cu) nanoscaffold electrodes present highly stable Li plating/stripping for more than 1000 h with a low voltage hysteresis less than 90 mV and a long lifespan over 1300 h at 1.0 mA cm–2 in carbonate‐based electrolytes. Impressively, the Li‐Au/Cu nanoscaffold||LiFePO4 full cells also exhibit exceptional cycling stability and rate performance. This work provides a promising strategy to construct dendrite‐free lithium metal anodes toward high‐performance lithium metal batteries.

In-situ mechanochemical synthesis of sub-micro Si/Sn@SiOx-C composite as high-rate anode material for lithium-ion batteries

Micrometer silicon (MSi) particles are prospective anode material for high energy-density lithium-ion batteries. Aiming at the scale-up production and the improvement in rate capability, a novel sub-micro Si/Sn@SiOx-C (SSSC) composite via a facile two-step process of milling and annealing is designed and synthesized. With the structural uniqueness including in-situ introduction of metallic tin (Sn) originated from mechano-reduction of nano tin dioxide (nano-SnO2) with MSi, dual-buffering of inner SiOx matrix and uniform surface carbon layer, SSSC electrodes exhibit impressive rate capability and stable cyclability. The optimum architecture of SSSC-73 (i.e. weight ratio of precursor MSi-to-SnO2 is 7:3) delivers stable cycling with 1102 mAh g−1 (at 0.5 A g−1) over 100 cycles and exceptional rate performance with a high capacity retention of 95% over 500 cycles at 2 A g−1. Particularly, this facile and cost-effective preparation of SSSC composites has no by-products, making it competitive in practical application.

Origin of anomalous high-rate Na-ion electrochemistry in layered bismuth telluride anodes

Summary van der Waals layered metal chalcogenide Bi2Te3 has shown exceptional capacity and rate capability in alkali-ion batteries but the underlying reaction mechanism with Li+, Na+, and K+ remains undiscovered. It is unexpected that Na+ electrochemistry outperforms Li+ and K+ at high current densities. Here, in situ transmission electron microscopy is used to uncover nanoscale transformations during lithiation, sodiation, and potassiation, which follows two-step conversion and alloying reactions with Li+ and Na+, and three-step intercalation-conversion-alloying reactions with K+. Counterintuitively, sodiation exhibits the highest reaction kinetics, and its origin can be elucidated by first-principles and finite-element simulations in two aspects. The lower interfacial strain accommodation energy between Bi2Te3 and its Na-conversion products allows more facile sodiation phase transformation than Li- and K-ion reactions. The higher electrochemo-mechanical stress concentration at the concave-shaped sodiation reaction front facilitates continued Na-ion diffusion and reaction propagation. These fundamental insights are essential for fast-charging alkali-ion batteries.

Construction of CoMoO4@Ni3S2 core-shell heterostructures nanorod arrays for high-performance supercapacitors

The core-shell CoMoO4 nanorods@Ni3S2 nanosheets (CMO@NS) for supercapacitor were prepared by a facile two-step hydrothermal process accompanying with annealing treatment. The influence of hydrothermal time on structures and electrochemical properties was studied in detail. Benefiting from the synergism-enhanced action of CoMoO4 and Ni3S2 and the novel core-shell heterostructure of the composite, the prepared electrode exhibits excellent electrochemical performance. CMO@NS employed as positive electrode for supercapacitor exhibits excellent areal specific capacitance (11.02 F cm−2 at 5 mA cm−2), exceptional rate performance (70.8% retention, even increasing the current density to 30 mA cm−2) and enhanced cycle performance (57.7% retention rate after 3000 cycles). Furthermore, an asymmetric supercapacitor device was fabricated, which achieves an ultra-high energy density of 0.412 mWh cm−2 at the power density of 4 mW cm−2 and a great cycle life with 81.25% capacitance retention over 3000 cycles. Thus, the core-shell CMO@NS could be a hopeful candidate for practical supercapacitor electrode materials.

Synergistic Effect of Nitrogen and Sulfur Dual‐Doping Endows TiO2 with Exceptional Sodium Storage Performance

AbstractImproving the diffusion kinetics of sodium ions within TiO2 and its intrinsic electronic conductivity is indispensable to enhance the rate capability and long cyclic stability of TiO2 anodes for sodium‐ion batteries. Although single‐heteroatom doping into TiO2 has been widely investigated, a comprehensive understanding of the effects of dual‐heteroatoms doping on the sodium storage performance of TiO2 is still lacking. Herein, nitrogen and sulfur dual‐doping is proposed to achieve a high doping concentration for anatase TiO2 hollow spheres. Experimental data and theoretical calculations reveal that N doping can efficiently narrow the bandgap of TiO2, while S doping is effective in facilitating Na+ diffusion within TiO2. Thus N and S codoped TiO2 shows remarkably boosted electronic conductivity, as well as accelerated sodium ion transfer kinetics owing to the synergistic effect of different doping heteroatoms, which leads to exceptional rate performance (307.5 and 156.4 mAh g−1 at 33.5 and 5025 mA g−1, respectively), and extraordinary cycling stability (90.5% retention over 2400 cycles at 3350 mA g−1). The greatly improved electrochemical performance emphasizes the importance of defects engineering in the rational design of advanced battery materials.

Sulfur-Rich Graphene Nanoboxes with Ultra-High Potassiation Capacity at Fast Charge: Storage Mechanisms and Device Performance.

It is a major challenge to achieve fast charging and high reversible capacity in potassium ion storing carbons. Here, we synthesized sulfur-rich graphene nanoboxes (SGNs) by one-step chemical vapor deposition to deliver exceptional rate and cyclability performance as potassium ion battery and potassium ion capacitor (PIC) anodes. The SGN electrode exhibits a record reversible capacity of 516 mAh g-1 at 0.05 A g-1, record fast charge capacity of 223 mA h g-1 at 1 A g-1, and exceptional stability with 89% capacity retention after 1000 cycles. Additionally, the SGN-based PIC displays highly favorable Ragone chart characteristics: 112 Wh kg-1at 505 W kg-1 and 28 Wh kg-1 at 14618 W kg-1 with 92% capacity retention after 6000 cycles. X-ray photoelectron spectroscopy analysis illustrates a charge storage sequence based primarily on reversible ion binding at the structural-chemical defects in the carbon and the reversible formation of K-S-C and K2S compounds. Transmission electron microscopy analysis demonstrates reversible dilation of graphene due to ion intercalation, which is a secondary source of capacity at low voltage. This intercalation mechanism is shown to be stable even at cycle 1000. Galvanostatic intermittent titration technique analysis yields diffusion coefficients from 10-10 to 10-12 cm2 s-1, an order of magnitude higher than S-free carbons. The direct electroanalytic/analytic comparison indicates that chemically bound sulfur increases the number of reversible ion bonding sites, promotes reaction-controlled over diffusion-controlled kinetics, and stabilizes the solid electrolyte interphase. It is also demonstrated that the initial Coulombic efficiency can be significantly improved by switching from a standard carbonate-based electrolyte to an ether-based one.

Doped graphene encapsulated SnP2O7 with enhanced conversion reactions from polyanions as a versatile anode material for sodium dual-ion battery

Tin-based ternary oxides have obtained much attention for energy storage systems due to high capacity based on alloying/dealloying reactions and improved cycling performance resulted from the inactive buffer matrix. Herein, SnP2O7 particles are encapsulated into N/P dual-doped graphene (SnP2O7/NPG), which is served as an universal anode material for sodium-ion batteries (SIBs) and sodium-based dual-ion batteries (SDIBs). Benefiting from the unique structure of tin-based ternary oxides and synergy effect of multicomponent, the obtained SnP2O7/NPG delivers a good reversible capacity of 412.9 mAh g−1 at 0.05 A g−1, superior cycling performance of 86.2 mAh g−1 at 2 A g−1 after 1000 cycles, and exceptional rate performance of 182.3 mAh g−1 at 2 A g−1 in Na+ half cells. Especially, assembly of SnP2O7/NPG with the graphite cathode could yield a SnP2O7/NPG-graphite SDIBs, which shows high rate performance (up to 2 A g−1) and good cycling stability over 100 cycles with a capacity retention of 63.2%. Furthermore, the Na+ insertion/extraction mechanism is systematically investigated using the extensive kinetics investigation. This work provides inspirations as to extending the wider application prospect of tin-based ternary oxides in energy storage systems.

Maximizing ion accessibility in MXene-knotted carbon nanotube composite electrodes for high-rate electrochemical energy storage

Improving the accessibility of ions in the electrodes of electrochemical energy storage devices is vital for charge storage and rate performance. In particular, the kinetics of ion transport in organic electrolytes is slow, especially at low operating temperatures. Herein, we report a new type of MXene-carbon nanotube (CNT) composite electrode that maximizes ion accessibility resulting in exceptional rate performance at low temperatures. The improved ion transport at low temperatures is made possible by breaking the conventional horizontal alignment of the two-dimensional layers of the MXene Ti3C2 by using specially designed knotted CNTs. The large, knot-like structures in the knotted CNTs prevent the usual restacking of the Ti3C2 flakes and create fast ion transport pathways. The MXene-knotted CNT composite electrodes achieve high capacitance (up to 130 F g−1 (276 F cm−3)) in organic electrolytes with high capacitance retention over a wide scan rate range of 10 mV s−1 to 10 V s−1. This study is also the first report utilizing MXene-based supercapacitors at low temperatures (down to −60 °C).

Contribution of Ultrahigh Electrochemical Performance of NiCo2O4 Nanoneedle-Based Free-Standing Electrode from Functionalized Carbon Cloth

Spinel structure NiCo2O4 suffers from poor electric conductivity and the resulted electrochemical properties in battery/supercapacitor system are still unsatisfied. In this paper, a free-standing electrode based on in-situ growth NiCo2O4 on carbon cloth has been synthesized by a surfactant-assisted solvothermal method (sodium dodecyl sulfate, SDS). The functional carbon cloth substrate makes unexpected contribution to the electrochemical lithium-ion storage. The assembled supercapacitor possesses ultrahigh pseudocapacitive properties with high mass loading. The specific capacitance of 2832[Formula: see text]F[Formula: see text]g[Formula: see text] has been obtained at 1[Formula: see text]A[Formula: see text]g[Formula: see text] current density with maintaining the high rate capability of 1620[Formula: see text]F[Formula: see text]g[Formula: see text] at 20[Formula: see text]A[Formula: see text]g[Formula: see text]. The obtained nanoneedle NiCo2O4/carbon cloth electrode also maintains a specific capacity of 2000[Formula: see text]mA[Formula: see text]h[Formula: see text]g[Formula: see text] at 40[Formula: see text]mA[Formula: see text]g[Formula: see text] and exceptional rate performance (1504[Formula: see text]mAh[Formula: see text]g[Formula: see text] at 400[Formula: see text]mA[Formula: see text]g[Formula: see text] when tested as anode material in lithium ion batteries.

Rational design of MOFs-derived Fe3O4@C interwoven with carbon nanotubes as sulfur host for advanced lithium‑sulfur batteries

Abstract The practical implementation of lithium‑sulfur (Li S) batteries has been hindered by limited power density and slow electrochemical reaction kinetics resulted from the shuttle effect of soluble polysulfides. Conventional carbonaceous materials are difficult to effectively adsorb polysulfides, and polar metal oxides are expected to adsorb polysulfides through strong interactions and promote electrochemical conversion. In this work, carbon nanotubes/MIL-88B microspheres were obtained by simple spray-drying, subsequently, carbon nanotubes/Fe3O4@C (CNT/Fe3O4@C) composites were obtained by high-temperature calcination, and Fe3O4@C nanorods was derived from MIL-88B. The interwoven CNT network forms a three-dimensional conductive path, which ensures that the sulfur cathode has excellent conductivity. The polar Fe3O4 nanoparticles are covered by carbon layer, which not only adsorb polysulfides through strong interaction, but also serve as a catalyst to improve the kinetics of chemical reactions. Benefiting from these characteristics, the CNT/Fe3O4@C composite is considered to be an excellent sulfur host, Li S batteries exhibit superior cyclability performance (with 0.062% decay per cycle at 1.5C), exceptional rate performance (674 mAh g−1 at 3C), and high area capacity (4.1 mAh cm−2 at 0.2C).

Bifunctional N-Doped Tungsten Trioxide Microspheres as Electrode Materials for Lithium-Ion Batteries and Direct Methanol Fuel Cells

Oxygen vacancies (OVs) have emerged as an efficient strategy to modulate the electronic structures, conductivity, and electrochemical properties of WO3. However, OVs are easily absorbed by water molecules or oxygen atoms, resulting in the poor stability of its electrocatalytic reaction. In the present work, we have demonstrated that nitrogen doping provides an alternative to improve the electrochemical properties of WO3, which plays a series of roles in reducing the band gap, improving the electron mobility, accelerating the Li+ ion diffusion, and providing more active sites for catalytic reactions. Consequently, N-doped WO3 microspheres exhibit low discharge–charge voltage gaps and high capacity retention as well as exceptional rate performance when used as anode materials for lithium-ion batteries (LIBs). Furthermore, the as-prepared Pt/N-WO3 catalyst also exhibits excellent electrocatalytic properties toward methanol electro-oxidation (MOR) including high activity, strong poison tolerance, and outstanding long-term stability owing to the synergetic effects between Pt and N-WO3.

Na2CoPO4F as a pseudocapacitive anode for high-performance and ultrastable hybrid sodium-ion capacitors

Sodium-ion capacitors (NICs) reported in the literature demonstrate relatively poor cycle retention (<90% after 10,000 cycles) and rate performance, which is not ideal for proposed applications such as regenerative brake charging. In this work, a 3 V NIC was fabricated using Na2CoPO4F (NCPF) as a next-generation anode and commercial activated carbon (AC) as the cathode in an organic electrolyte. The constructed NCPF//AC NIC exhibited exceptional rate performance, retaining 78% of its energy density (corresponding to 24 Wh kg−1) when the power density was ramped from 125 to 5000 W kg−1. In addition, its long-term stability when cycled from 0 to 3 V is among the highest reported in the literature, retaining 93% of its energy density (24 Wh kg−1) after 100,000 cycles at 1 kW kg−1. Furthermore, at an elevated voltage range of 0–3.25 V, the NIC retained 80% of its energy density (26 Wh kg−1) after 30,000 cycles at 375 W kg−1. The performance is ascribed to the kinetic compatibility between the adsorptive cathode and pseudocapacitive anode, where pseudocapacitance is enhanced by the nanosized morphology on the surface of NCPF. The NIC system reported herein demonstrates supercapacitor-type benchmarks while also possessing a higher energy density.

A stable and superior performance of Na3V2(PO4)3/C nanocomposites as cathode for sodium-ion batteries

Na3V2(PO4)3 suffers from poor performance and cyclability arising from low electronic conductivity. Na3V2(PO4)3 nanosheets have been successfully synthesized by a hydrothermal method and coated with a carbon layer from β-cyclodextrin. The NVP/C nanocomposite shows superior high-rate and ultralong-lifespan performances owning to large number of oxygenous groups from β-cyclodextrin, which are beneficial to a uniform adsorption on the surface of electrode materials. The NVP/C delivers 74 mAh g−1 even after 2000 cycles at a rate of 20 C and an exceptional rate performance (66 mAh g−1at 50 C).

Rationally designed Ni2P/Ni/C as a positive electrode for high-performance hybrid supercapacitors

Ni2P/Ni/C is fabricated a simple simultaneous carbonization and phosphidation process. It displays exceptional rate performance with excellent cycling ability, mainly resulting from accelerated charge transfer ability and stable porous structure.

Cu-dispersed cobalt oxides as high volumetric capacity anode materials for Li-ion storage

The widely adopted approach of hybridizing transition metal oxides (TMOs) with carbon materials can successfully recover the performance of TMOs for Li-ion storage. Though, the introduction of carbon may significantly reduce tap density, leading to a low volumetric capacity. Herein, copper was utilized to disperse and stabilize cobalt oxides to attain higher volumetric capacity. Thanks to the highly electronic conductive Cu-network and the designed Li-ion diffusion pore structure, the composite exhibits enormously high capacity and exceptional rate performance as anode materials for Li-ion battery. After 250 cycles at 0.1 ​A ​g−1, the specific volumetric capacity can still be maintained at 2174.2 ​mA ​h ​cm−3 (1402.7 ​mA ​h ​g−1), even higher than that of Li metal (2061 ​mA ​h ​cm−3). We hope this new design criteria could further open opportunities in exploration and advance the practical application of TMOs.

3D Lithiophilic "Hairy" Si Nanowire Arrays @ Carbon Scaffold Favor a Flexible and Stable Lithium Composite Anode.

Lithium metal anode is considered to be a promising candidate for high-energy-density lithium-based batteries. However, the safety issue induced by uncontrollable dendrite growth hinders the commercialization of a Li anode. Herein, self-supported three-dimensional flexible carbon cloth covered with a lithiophilic silicon nanowire array is constructed as the host for loading of molten Li to achieve the C/SiNW/Li composite anode. The electrode component of the carbon cloth provides the flexible and conductive substrate to accommodate the volume change during the stripping/plating of Li and facilitate more efficient electron transport, while silicon nanowires improve the wettability of the carbon host to liquefied Li and render uniform Li deposition on the surface of the composite electrode. The as-prepared C/SiNW/Li composite anode exhibits enhanced cycling stability with a low hysteresis of 40 mV for more than 200 h and a better rate tolerance even at a current density of up to 5 mA cm-2. When coupling with the LiNi0.5Mn1.5O4 cathode, the full cells using the C/SiNW/Li composite anode demonstrate a remarkable electrochemical performance with an exceptional rate performance of up to 10 C and stable long-term cycling (the capacity retention of 62% at a 5 C rate over 2000 cycles), which is much higher than the cells with pure Li anode. This work provides a universal strategy to fabricate the flexible and stable carbon-based Li metal anode toward high-energy-density batteries.

Nitrogen-Containing Organic Electrode Materials for Li-Ion Batteries and Beyond

The commercial Li-ion batteries cause severe environmental challenges such as heavy metal pollution and global warming due to the use of toxic cobalt-based inorganic materials and the huge amount of CO2 release from the battery material production and recycling process. To overcome these environmental challenges, the inexpensive, abundant, environmentally benign and sustainable organic electrode materials and polymers provide an ideal solution. In our work, we demonstrated that the nitrogen-containing organic materials such as carboxylated azo compounds and imine-based polymers are promising electrode materials for Li-ion batteries and beyond. As an example, poly-hexaazatrinaphthalene (PHATN), which is an electron-deficient, rigid and planar aromatic discotic system with pyrazine functional groups, enables fast charge/discharge of Na, Mg and Al ions with high cycling stability. In Na-ion batteries (NIBs), PHATN delivers a reversible capacity of 165 mA h/g and 100 mA h/g after ultra-long 10,000 and 50,000 cycles at ultra-high current densities of 2 A/g (5C) and 10 A/g (25C), respectively. These capacity delivery and retention, to our best knowledge, are the highest among both organic and inorganic cathodes reported for NIBs. The exceptional rate and cycle life seen in NIBs carry over to RMBs and RABs as well. The mechanism for exceptional rate and cycling performance of PHATN is investigated using density functional theory (DFT), ex situ Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). For the first time, we proved that imine group (C=N) in the conjugated polymer can reversibly react with Mg2+ and Al3+ in the rechargeable batteries. This work demonstrates that the pyrazine-based polymer cathode is promising for developing environmentally benign, high-energy-density, fast and ultra-stable rechargeable batteries.

Mesoporous MnO2 based composite electrode for efficient alkali-metal-ion storage

The mesoporous δ-MnO2-based nanostructure is elaborately designed for overcoming the main bottleneck problems for lithium and sodium storage. Based on density functional theory, MnO2 composite possesses high binder energy and low migration barrier for energy storage, which are beneficial for improving sluggish electrochemical kinetics. Additionally, dendritic metal growth is inhibited via electrostatic force. All these merits ensure the exceptional rate and cycle performance during cycling process. Coupling MnO2 with Ni-Co-Oxide promotes homogeneous nucleation sites, guiding Li/Na metal deposition/exfoliation and suppressing dendritic lithium/sodium growth. Simultaneously, abundant grain boundaries between MnO2-C and Ni-Co-Oxide bring more enriched sites for fast ion diffusion and pseudo-capacitive storage processes. The enriched surface defects lower the impedance to achieve fast transport kinetics. Making full use of the structure, component and composition, such MnO2 based electrodes exhibit superior cycle ability and high capacity for both lithium and sodium storage. This work supplies the robust SEI design protocol and sheds new light on developing stable lithium and sodium ion batteries.