Unlocking the Effect of Chain Length and Terminal Group on Ethylene Glycol Ether Family Toward Advanced Aqueous Electrolytes.

Constructing high-performance hybrid electrolyte is important to advanced aqueous electrochemical energy storage devices. However, due to the lack of in-depth understanding of how the molecule structures of cosolvent additives influence the properties of electrolytes significantly impeded the development of hybrid electrolytes. Herein, a series of hybrid electrolytes are prepared by using ethylene glycol ether with different chain lengths and terminal groups as additives. The optimized 2 m LiTFSI-90%DDm hybrid electrolyte prepared from diethylene glycol dimethyl ether (DDm) molecule showcases excellent comprehensive performance and significantly enhances the operating voltage of supercapacitors (SCs) to 2.5 V by suppressing the activity of water. Moreover, the SC with 2 m LiTFSI-90%DDm hybrid electrolyte supplies a long-term cycling life of 50 000 cycles at 1 A g-1 with 92.3% capacitance retention as well as excellent low temperature (-40 ºC) cycling performance (10 000 times at 0.2 A g-1). Universally, Zn//polyaniline full cell with 2 m Zn(OTf)2-90%DDm electrolyte manifests outstanding cycling performance in terms of 77.9% capacity retention after 2,000 cycles and a dendrite-free Zn anode. This work inspires new thinking of developing advanced hybrid electrolytes by cosolvent molecule design toward high-performance energy storage devices.

Micro/meso-porous Double-shell Hollow Carbon Spheres through Spatially Confined Pyrolysis for Supercapacitors and Zinc-ion Capacitor.

Energy storage in supercapacitors and hybrid zinc ion capacitors (ZIC) using porous carbon materials offers a promsing alternative method for clean energy solutions. The unique combination of hierarchical porous structure and nitrogen doping in these materials has demonstrated significant capacity for energy storage. Nevertheless, the full potential of these materials, particularly the relationship between pore structure configuration and performance, remains underexplored. Herein, a confined pyrolysis strategy based on the polymerization characteristics of polydopamine (PDA) was developed to construction of hollow carbon spheres with microporous/mesoporous dual shell structure. The depth of micropores and cavity can be controlled by adjusting the duration of heat treatment and hydrothermal treatment, in accordance with the decomposition and polymerization characteristics of PDA. Due to the elasticity of this structure, the relationship between the micro/mesoporous depth of the prepared carbon spheres and the energy storage performance in supercapacitors and ZIC is established. Through optimizing the ion transport capacity of carbon spheres and considering the influence of its internal cavity structure on energy storage, the resulting carbon spheres exhibit high specific capacitance of 389 F g-1 in supercapacitor and specific capacitance of 260 F g-1 and excellent stability with 99.3% retention after 30000 chare/discharge cycles in ZIC.

Polycation-Regulated Electrolyte and Interfacial Electric Fields for Stable Zinc Metal Batteries.

Zn metal as one of promising anode materials for aqueous batteries but suffers from disreputable dendrite growth, grievous hydrogen evolution and corrosion. Here, a polycation additive, polydiallyl dimethylammonium chloride (PDD), is introduced to achieve long-term and highly reversible Zn plating/stripping. Specifically, the PDD can simultaneously regulate the electric fields of electrolyte and Zn/electrolyte interface to improve Zn2+ migration behaviors and guide dominant Zn (002) deposition, which is veritably detected by Zeta potential, Kelvin probe force microscopy and scanning electrochemical microscopy. Moreover, PDD also creates a positive charge-rich protective outer layer and a N-rich hybrid inner layer, which accelerates the Zn2+ desolvation during plating process and blocks the direct contact between water molecules and Zn anode. Thereby, the reversibility and long-term stability of Zn anodes are substantially improved, as certified by a higher average coulombic efficiency of 99.7 % for Zn||Cu cells and 22 times longer life for Zn||Zn cells compared with that of PDD-free electrolyte.

Transition Metal-Nitrogen-Carbon Single-Atom Catalysts Enhanced CO2 Electroreduction Reaction: A Review.

As the global energy crisis and environmental challenges worsen, CO2 conversion has emerged as a focal point in international research. CO2 electroreduction reaction (CO2ER) is a green and sustainable technology that converts CO2 into high-value chemicals, thereby achieving the recycling of carbon resources. However, the activity and selectivity are constrained by the performance of the catalyst. Although traditional N-doped carbon-based catalysts exhibit excellent performance toward CO2ER, the atomic utilization rate in these materials is far from 100%. Single atom catalysts (SACs) can attain nearly 100% atomic utilization efficiency because of the fully exposing metal atoms. Therefore, SACs have emerged as one of the hot research materials in the field of CO2ER. Recently, transition metal-nitrogen-carbon single-atom catalysts (TM-N-C SACs) have flourished because of their extraordinary catalytic activity, low cost, and excellent stability, demonstrating enormous application prospects in CO2ER. In this review, we concentrate on TM-N-C SACs that electrochemically reduce CO2 to high value products. A comprehensive and detailed discussion were conducted on the synthesis method, chemical structure, chemical characterization of TM-N-C SACs, as well as their catalytic performance, active sources, and mechanism exploration for CO2ER. Finally, challenges and prospects for commercial application of TM-N-C SACs catalysts suitable for CO2ER are proposed.

Eliminating the Micropore Confinement Effect of Carbonaceous Electrodes for Promoting Zn-Ion Storage Capability.

Zinc-ion capacitors (ZICs) are promising technology for large-scale energy storage by integrating the attributes of supercapacitors and zinc-ion batteries. Unfortunately, the insufficient Zn2+ -storage active sites of carbonaceous cathode materials and the mismatch of pore sizes with charge carriers lead to unsatisfactory Zn2+ storage capability. Herein, new insights for boosting Zn2+ storage capability of activated nitrogen-doped hierarchical porous carbon materials (ANHPC-x) are reported by effectively eliminating the micropore confinement effect and synchronously elevating the utilization of active sites. Therefore, the best-performed ANHPC-2 delivers impressive electrochemical properties for ZICs in terms of excellent capacity (199.1 mAh g-1 ), energy density (155.2 Wh kg-1 ), and durability (65 000 cycles). Systematic ex situ characterizations together with in situ electrochemical quartz crystal microbalance and Raman spectra measurements reveal that the remarkable electrochemical performance is assigned to the synergism of the Zn2+ , H+ , and SO4 2- co-adsorption mechanism and reversible chemical adsorption. Furthermore, the ANHPC-2-based quasi-solid-state ZIC demonstrates excellent electrochemical capability with an ultralong lifespan of up to 100 000 cycles. This work not only provides a promising strategy to improve the Zn2+ storage capability of carbonaceous materials but also sheds lights on charge-storage mechanism and advanced electrode materials' design for ZICs toward practical applications.

High Energy and Power Zinc Ion Capacitors: A Dual-Ion Adsorption and Reversible Chemical Adsorption Coupling Mechanism.

Zinc ion capacitors (ZICs) hold great promise in large-scale energy storage by inheriting the superiorities of zinc ion batteries and supercapacitors. However, the mismatch of kinetics and capacity between a Zn anode and a capacitive-type cathode is still the Achilles' heel of this technology. Herein, porous carbons are fabricated by using tetra-alkali metal pyromellitic acid salts as precursors through a carbonization/self-activation procedure for enhancing zinc ion storage. The optimized rubidium-activated porous carbon (RbPC) is verified to hold immense surface area, suitable porosity structure, massive lattice defects, and luxuriant oxygen functional groups. These structural and compositional merits endow RbPC with the promoted zinc ion storage capability and more matchable kinetics and capacity with a Zn anode. Consequently, RbPC-based ZIC delivers a high specific energy of 178.2 W h kg-1 and a peak power density of 72.3 kW kg-1. A systematic ex situ characterization analysis coupled with in situ electrochemical quartz crystal microbalance tests reveal that the preeminent zinc ion storage properties are ascribed to the synergistic effect of the dual-ion adsorption and reversible chemical adsorption of RbPC. This work provides an efficient strategy to the rational design and construction of high-performance electrodes for ZICs and furthers the fundamental understanding of their charge storage mechanisms or extends the understanding toward other electrochemical energy storage devices.

Fast assembly of MXene hydrogels by interfacial electrostatic interaction for supercapacitors.

A simple and fast method for preparing MXene hydrogels is proposed by introducing protonated thionine molecules into a MXene dispersion through electrostatic interaction. Such a 3D hydrogel effectively suppressed restacking and oxidation, and enlarged the surface utilization of the MXene, producing an improved specific capacitance of 163 F g-1 at 1 A g-1 and excellent stability when used as an electrode material for supercapacitors.