Stabilizing a zinc anode via a tunable covalent organic framework-based solid electrolyte interphase.

Zinc (Zn) is an excellent material for use as an anode for rechargeable batteries in water-based electrolytes. Nevertheless, the high activity of water leads to Zn corrosion and hydrogen evolution, along with the formation of dendrites on the Zn surface during repeated charge-discharge (CD) cycles. To protect the Zn anode and limit parasitic side reactions, an artificial solid electrolyte interphase (ASEI) protective layer is an effective strategy. Herein, an ASEI made of a covalent organic framework (COFs: HqTp and BpTp) was fabricated on the surface of a Zn anode via Schiff base reactions of aldehyde and amine linkers. It is seen that COFs can regulate the Zn-ion flux, resulting in dendritic-free Zn. COFs can also mitigate the formation of an irreversible passive layer and the hydrogen evolution reaction (HER). Zn plating/stripping tests using a symmetrical cell suggest that HqTpCOF@Zn shows superior stability and greater coulombic efficiency (CE) compared to bare Zn. The full cell having COFs@Zn also displays much improved cyclability. As a result, the COF proves to be a promising ASEI material to enhance the stability of the Zn anode in aqueous media.

Polypyrrole/reduced graphene oxide composites coated zinc anode with dendrite suppression feature for boosting performances of zinc ion battery.

Metallic zinc (Zn) anode has been received a great promise for aqueous rechargeable zinc-ion batteries (ZIBs) due to its intrinsic safety, low cost, and high volumetric capacity. However, the dendrite formation regarding the surface corrosion is the critical problems to achieve the high performance and the long lifespans of ZIBs. Here, we purpose the facile cyclic voltammetry deposition of polypyrrole/reduced graphene oxide (PPy/rGO) composites coated onto Zn 3D surface as Zn anode for ZIBs. As results, the deposited PPy/rGO layer demonstrates the homogeneous distribution covering onto Zn surface, effectively suppressing the formation of dendrite. Additionally, a symmetric cell of the PPy/rGO coated Zn remarkably enhances an electrochemical cycling with a low voltage hysteresis for zinc plating/stripping, which is superior to the pristine Zn cell. In addition, the deposited layer of PPy/rGO on Zn effectively improves the reactivity of electrochemically active surface area and the intrinsic electronic configurations, participating in extraction/intercalation of Zn2+ ions and leading to enhance ZIBs performance. The coin cell battery of Zn-PPy/rGO//MnO2 can deliver a high initial discharge capacity of 325 mAh/g at 0.5A/g with a good cycling stability up to 50% capacity retention after 300 cycles. Thus, these achieved results of Zn-PPy/rGO//MnO2 battery with dendrite-free feature effectively enhance the life-performance of ZIBs and open the way of the designed coating composite materials to suppress dendrite issues.

Controllable Morphology of Sea-Urchin-like Nickel-Cobalt Carbonate Hydroxide as a Supercapacitor Electrode with Battery-like Behavior.

Nickel-cobalt carbonate hydroxide with a three-dimensional (3D) sea-urchin-like structure was successfully developed by the hydrothermal process. The obtained structure enables the enhancement of charge/ion diffusion for the high-performance supercapacitor electrodes. The mole ratio of nickel to cobalt plays a vital role in the densely packed sea-urchin-like structure formation and electrochemical properties. At optimized nickel/cobalt mole ratio (1:2), the highest specific capacitance of 950.2 F g-1 at 1 A g-1 and the excellent cycling stability of 178.3% after 3000 charging/discharging cycles at 40 mV s-1 are achieved. This nickel-cobalt carbonate hydroxide electrode yields an energy density in the range of 42.9-15.8 Wh kg-1, with power density in the range of 285.0-2849.9 W kg-1. The charge/discharge mechanism at the atomic level as monitored by time-resolved X-ray absorption spectroscopy (TR-XAS) indicates that the high capacitance behavior in a nickel-cobalt carbonate hydroxide is mainly dominated by cobalt carbonate hydroxide.

A self-sacrifice template strategy to synthesize Co-LDH/MXene for lithium-ion batteries.

To overcome the limitations of both LDHs and MXenes, we develop a self-sacrifice template strategy using a zeolite imidazolate framework-67 (ZIF-67) to derive Co-LDH anchored on an MXene conductive substrate (Co-LDH/MXene). In this process, ZIF-67 grows on the MXene nanosheets, then spontaneously transforms into Co-LDH/MXene in aqueous solution at room temperature. As the LIB anode, it shows a reversible capacity of 854.9 and 398.0 mAh g-1 at 0.1 and 1 A g-1, respectively. This work proposes a feasible synthesis method for the in situ construction of a Co-LDH/MXene hybrid, which may be suitable for other MXenes.

Antioxidant and UV-Blocking Properties of a Carboxymethyl Cellulose-Lignin Composite Film Produced from Oil Palm Empty Fruit Bunch.

Oil palm empty fruit bunch (EFB) pulp with the highest cellulose content of 83.42% was obtained from an optimized process of acid pretreatment (0.5% v/v H2SO4), alkaline extraction (15% w/w NaOH), and hydrogen peroxide bleaching (10% w/v H2O2), respectively. The EFB cellulose was carboxymethylated, and the obtained carboxymethyl cellulose (CMC) was readily water-soluble (81.32%). The EFB CMC was blended with glycerol and cast into a composite film. Lignin that precipitated from the EFB black liquor was also incorporated into the film at different concentrations, and its effect on the UV-blocking properties of the film was determined. Interestingly, the EFB CMC film without lignin addition completely blocked UV-B transmittance. The incorporation of lignin at all concentrations significantly enhanced the UV-A blocking and other physical properties of the film, including the surface roughness, thickness, and thermal stability, although the tensile strength and water vapor permeability were not significantly affected. Complete UV-A and UV-B blocking were observed when lignin was added at 0.2% (w/v), and the film also exhibited the highest antioxidant activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radicals with an half-maximal inhibitory concentration (IC50) value of 3.87 mg mL-1.

In situ hydrothermal synthesis of nickel cobalt sulfide nanoparticles embedded on nitrogen and sulfur dual doped graphene for a high performance supercapacitor electrode.

Nickel cobalt sulfide nanoparticles (NCS) embedded onto a nitrogen and sulfur dual doped graphene (NS-G) surface are successfully synthesized via a two-step facile hydrothermal process. The electrical double-layer capacitor of NS-G acts as a supporting host for the growth of pseudocapacitance NCS nanoparticles, thus enhancing the synergistic electrochemical performance. The specific capacitance values of 1420.2 F g-1 at 10 mV s-1 and 630.6 F g-1 at 1 A g-1 are achieved with an impressive capability rate of 76.6% preservation at 10 A g-1. Furthermore, the integrating NiCo2S4 nanoparticles embedding onto the NS-G surface also present a surprising improvement in the cycle performance, maintaining 110% retention after 10 000 cycles. Owing to the unique morphology an impressive energy density of 19.35 W h kg-1 at a power density of 235.0 W kg-1 suggests its potential application in high-performance supercapacitors.

Polypyrrole nanoparticles embedded nitrogen-doped graphene composites as novel cathode for long life cycles and high-power zinc-ion hybrid supercapacitors.

The well-designed network structure of synthetic polypyrrole (PPy) nanoparticles embedded on a nitrogen-doped graphene (N-rGO) surface was utilized as a cathode for aqueous zinc-ion hybrid supercapacitors. Owing to the combination of the redox surface of PPy and the two-dimensional network structure of N-rGO, the PPy/N-rGO cathode affords rapid transport channels for Zn2+ ion adsorption/desorption and a faradaic reaction toward the synergistic composite materials. Subsequently, the constructed zinc-ion hybrid supercapacitors with the optimized PPy/N-rGO cathode composites deliver the highest capacity of 145.32 mA h g-1 at 0.1 A g-1 and the maximum energy density of 232.50 W h kg-1 at a power density of 160 W kg-1. Besides this, excellent cycling stability of 85% retention after 10 000 charge-discharge cycles at 7.0 A g-1 was achieved. The high-rate capabilities with long life cycle performance of these novel zinc-ion hybrid supercapacitors could find practical use in a wide range of applications, ranging from next-generation electronic devices to large-scale stationary energy storage.

MnO2 Heterostructure on Carbon Nanotubes as Cathode Material for Aqueous Zinc-Ion Batteries.

Due to their cost effectiveness, high safety, and eco-friendliness, zinc-ion batteries (ZIBs) are receiving much attention nowadays. In the production of rechargeable ZIBs, the cathode plays an important role. Manganese oxide (MnO2) is considered the most promising and widely investigated intercalation cathode material. Nonetheless, MnO2 cathodes are subjected to challenging issues viz. limited capacity, low rate capability and poor cycling stability. It is seen that the MnO2 heterostructure can enable long-term cycling stability in different types of energy devices. Herein, a versatile chemical method for the preparation of MnO2 heterostructure on multi-walled carbon nanotubes (MNH-CNT) is reported. Besides, the synthesized MNH-CNT is composed of δ-MnO2 and γ-MnO2. A ZIB using the MNH-CNT cathode delivers a high initial discharge capacity of 236 mAh g-1 at 400 mA g-1, 108 mAh g-1 at 1600 mA g-1 and excellent cycling stability. A pseudocapacitive behavior investigation demonstrates fast zinc ion diffusion via a diffusion-controlled process with low capacitive contribution. Overall, the MNH-CNT cathode is seen to exhibit superior electrochemical performance. This work presents new opportunities for improving the discharge capacity and cycling stability of aqueous ZIBs.