Highly Dispersed Antimony-Bismuth Alloy Encapsulated in Carbon Nanofibers for Ultrastable K-Ion Batteries.

Antimony-based alloys have appealed to an ever-increasing interest for potassium ion storage due to their high theoretical capacity and safe voltage. However, sluggish kinetics and the large radius of K+ lead to limited rate performance and severe capacity fading. In this Letter, highly dispersed antimony-bismuth alloy nanoparticles confined in carbon fibers are fabricated through an electrospinning technology followed by heat treatment. The BiSb nanoparticles are uniformly confined into the carbon fibers, which facilitate rapid electron transport and inhibit the volume change during cycling owing to the synergistic effect of the BiSb alloy and carbon confinement engineering. Furthermore, the effect of a potassium bis(fluorosulfonyl)imide (KFSI) electrolyte with different concentrations has been investigated. Theoretical calculation demonstrates that the incorporation of Bi metal is favorable for potassium adsorption. The combination of delicate nanofiber morphology and electrolyte chemistry endows the fiber composite with an improved reversible capacity of 274.4 mAh g-1, promising rate capability, and cycling stability upon 500 cycles.

Dealloying Synthesis of Silicon Nanotubes for High-Performance Lithium Ion Batteries.

The front cover artwork is provided by Dr. Ping Nie and Prof. Limin Chang at Jilin Normal University. The image shows one-dimensional silicon-nitrogen-doped carbon nanotube composite fabricated through a dealloying process. The nanotube engineered silicon coupled with conductive carbon coating synergistically boosts the electrochemical performance. Read the full text of the Research Article at 10.1002/cphc.202100832.

Dealloying Synthesis of Silicon Nanotubes for High-Performance Lithium Ion Batteries.

Practical applications of silicon-based anodes in lithium ion batteries have attracted unprecedented attentions due to the merits of extraordinary energy density, high safety and low cost. Nevertheless, the inevitable huge volume change upon lithiation and delithiation brings about silicon electrode integrity damage and fast capacity fading, hampering the large-scale application. Herein, a novel one-dimensional tubular silicon-nitrogen doped carbon composite (Si@NC) with a core-shell structure has been fabricated using silicon magnesium alloy and polydopamine as a template and precursor. The as-obtained composite exhibits remarkable specific capacity and ultrafast redox kinetics, an outstanding cycling stability with fine capacity of 583.6 mAh g-1 at 0.5 A g-1 over 200 cycles is delivered. Moreover, a full cell matched with LiFePO4 cathode has demonstrated a reversible capacity of 148.8 mAh g-1 with high Coulombic efficiency as well as an excellent energy density of 396 Wh kg-1 . The nanotube structure engineering and silicon confined in nitrogen doped carbon effectively alleviate the volume expansion and endow the composite with superior stability. The robust strategy developed here gives a new insight into designing silicon anodes for enhanced lithium storage properties.

Perovskite-type CaMnO3 anode material for highly efficient and stable lithium ion storage.

Lithium ion batteries are attracting ever increasing attention due to their advantages of high energy/ power density, environmental friendly, lifetime and low cost. As a star in the field of materials and energy, perovskites have received extensive attention due to their attracting physical and chemical properties. Herein, CaMnO3, one material from the perovskite family is introduced as a novel anode material for lithium ion batteries, and its electrochemical performance at different temperatures is systematically investigated. CaMnO3 has been synthesized using a liquid phase synthesis method followed by high temperature calcination. The as-obtained CaMnO3 exhibits an initial high discharge capacity of 708.4 mAh g-1, superior rate capability and stable cycling performance at room temperature, the specific capacity is 102.5 mAh g-1 after 500 cycles at a current density of 0.1 A g-1. Additionally, at an extreme temperature of 0 °C, the discapacity can reach 138.2 mAh g-1 at a current density of 0.05 A g-1. At high temperature of 50 °C, the reversible discharge capacity is up to 216.5 mAh g-1under the same condition. It is believed that this contribution may lay the foundation for the application of perovskites in other rechargeable batteries and energy storage devices.

Emerging Potassium-ion Hybrid Capacitors.

As a new type of capacitor-battery hybrid energy storage device, metal-ion capacitors have attracted widespread attention because of their high-power density while ensuring energy density and long lifespan. Potassium-ion capacitors (KICs) featuring the merits of abundant potassium resources, lower standard electrode potential, and low cost have been considered as potential alternatives to lithium-/sodium-ion capacitors. However, KICs still face issues including unsatisfactory reaction kinetics, low energy density, and poor lifetime owing to the large radius of the potassium ion. In this Review, the importance of emerging potassium-ion capacitor is addressed. The Review offers a brief discussion of the fundamental working principle of KICs, along with an overview of recent advances and achievements of a variety of electrode materials for dual carbon and non-dual carbon KICs. Furthermore, electrolyte chemistry, binders as well as electrode/electrolyte interface, are summarized. Finally, existing challenges and perspectives on further development of KICs are also presented.

Iron-decorated nitrogen-rich carbons as efficient oxygen reduction electrocatalysts for Zn-air batteries.

A low-cost and scalable method has been developed to synthesize Fe-decorated N-rich carbon electrocatalysts for the oxygen reduction reaction (ORR) based on pyrolysis of metal carbonyls containing metal-organic frameworks (MOFs). Such a method simultaneously optimizes the Fe-related active sites and the porous structure of the catalysts. Accordingly, the best-performing Fe-NC-900-M catalyst shows excellent ORR activity with a half-wave potential of 0.91 V vs. RHE, exceeding that of the 40% Pt/C catalyst in alkaline media. Furthermore, the zinc-air batteries constructed with Fe-NC-900-M as the cathode catalyst exhibit high open-circuit voltage (1.5 V) and peak power density (271 mW cm-2), and outperform most zinc-air batteries with noble-metal free ORR catalysts.

Graphene Caging Silicon Particles for High-Performance Lithium-Ion Batteries.

Silicon holds great promise as an anode material for lithium-ion batteries with higher energy density; its implication, however, is limited by rapid capacity fading. A catalytic growth of graphene cages on composite particles of magnesium oxide and silicon, which are made by magnesiothermic reduction reaction of silica particles, is reported herein. Catalyzed by the magnesium oxide, graphene cages can be conformally grown onto the composite particles, leading to the formation of hollow graphene-encapsulated Si particles. Such materials exhibit excellent lithium storage properties in terms of high specific capacity, remarkable rate capability (890 mAh g-1 at 5 A g-1 ), and good cycling retention over 200 cycles with consistently high coulombic efficiency at a current density of 1 A g-1 . A full battery test using LiCoO2 as the cathode demonstrates a high energy density of 329 Wh kg-1 .

Prussian Blue Analogue with Fast Kinetics Through Electronic Coupling for Sodium Ion Batteries.

Alternative battery systems based on the chemistry of sodium are being considered to offer sustainability and cost-effectiveness. Herein, a simple and new method is demonstrated to enable nickel hexacyanoferrate (NiHCF) Prussian blue analogues (PBA) nanocrystals to be an excellent host for sodium ion storage by functionalization with redox guest molecule. The method is achieved by using NiHCF PBA powders infiltrated with the 7,7,8,8-tetracyanoquinododimethane (TCNQ) solution. Experimental and ab initio calculations results suggest that TCNQ molecule bridging with Fe atoms in NiHCF Prussian blue analogue leads to electronic coupling between TCNQ molecules and NiHCF open-framework, which functions as an electrical highway for electron motion and conductivity enhancement. Combining the merits including high electronic conductivity, open framework structure, nanocrystal, and interconnected mesopores, the NiHCF/TCNQ shows high specific capacity, fast kinetics and good cycling stability, delivering a high specific capacity of 35 mAh g-1 after 2000 cycles, corresponding a capacity loss of 0.035% decay per cycle.

Pseudocapacitive Sodium Storage in Mesoporous Single-Crystal-like TiO2-Graphene Nanocomposite Enables High-Performance Sodium-Ion Capacitors.

Sodium-ion capacitors can potentially combine the virtues of high power capability of conventional electrochemical capacitors and high energy density of batteries. However, the lack of high-performance electrode materials has been the major challenge of sodium-based energy storage devices. In this work, we report a microwave-assisted synthesis of single-crystal-like anatase TiO2 mesocages anchored on graphene as a sodium storage material. The architecture of the nanocomposite results in pseudocapacitive charge storage behavior with fast kinetics, high reversibility, and negligible degradation to the micro/nanostructure. The nanocomposite delivers a high capacity of 268 mAh g-1 at 0.2 C, which remains 126 mAh g-1 at 10 C for over 18 000 cycles. Coupling with a carbon-based cathode, a full cell of sodium-ion capacitor successfully demonstrates a high energy density of 64.2 Wh kg-1 at 56.3 W kg-1 and 25.8 Wh kg-1 at 1357 W kg-1, as well as an ultralong lifespan of 10 000 cycles with over 90% of capacity retention.

Regenerative Polysulfide-Scavenging Layers Enabling Lithium-Sulfur Batteries with High Energy Density and Prolonged Cycling Life.

Lithium-sulfur batteries, notable for high theoretical energy density, environmental benignity, and low cost, hold great potential for next-generation energy storage. Polysulfides, the intermediates generated during cycling, may shuttle between electrodes, compromising the energy density and cycling life. We report herein a class of regenerative polysulfide-scavenging layers (RSL), which effectively immobilize and regenerate polysulfides, especially for electrodes with high sulfur loadings (e.g., 6 mg cm-2). The resulting cells exhibit high gravimetric energy density of 365 Wh kg-1, initial areal capacity of 7.94 mAh cm-2, low self-discharge rate of 2.45% after resting for 3 days, and dramatically prolonged cycling life. Such blocking effects have been thoroughly investigated and correlated with the work functions of the oxides as well as their bond energies with polysulfides. This work offers not only a class of RSL to mitigate shuttling effect but also a quantified design framework for advanced lithium-sulfur batteries.

Hierarchical Nanostructured WO3 with Biomimetic Proton Channels and Mixed Ionic-Electronic Conductivity for Electrochemical Energy Storage.

Protein channels in biologic systems can effectively transport ions such as proton (H(+)), sodium (Na(+)), and calcium (Ca(+)) ions. However, none of such channels is able to conduct electrons. Inspired by the biologic proton channels, we report a novel hierarchical nanostructured hydrous hexagonal WO3 (h-WO3) which can conduct both protons and electrons. This mixed protonic-electronic conductor (MPEC) can be synthesized by a facile single-step hydrothermal reaction at low temperature, which results in a three-dimensional nanostructure self-assembled from h-WO3 nanorods. Such a unique h-WO3 contains biomimetic proton channels where single-file water chains embedded within the electron-conducting matrix, which is critical for fast electrokinetics. The mixed conductivities, high redox capacitance, and structural robustness afford the h-WO3 with unprecedented electrochemical performance, including high capacitance, fast charge/discharge capability, and very long cycling life (>50,000 cycles without capacitance decay), thus providing a new platform for a broad range of applications.

Mesoporous crystalline-amorphous oxide nanocomposite network for high-performance lithium storage.

Mesoporous nanocomposites composed of crystalline and amorphous oxides network were successfully synthesized by a continuous aerosol spray process; electrodes made from such nanocomposites with a thin-layer of protective oxide coating exhibit high capacity and long cycling life for lithium storage.