Metal-Organic Framework Materials for Electrochemical Supercapacitors

Exploring new materials with high stability and capacity is full of challenges in sustainable energy conversion and storage systems.Metal-organic frameworks(MOFs),as a new type of porous material,show the advantages of large specific surface area,high porosity,low density,and adjustable pore size,exhibiting a broad application prospect in the field of electrocatalytic reactions,batteries,particularly in the field of supercapacitors.This comprehensive review outlines the recent progress in synthetic methods and electrochemical performances of MOF materials,as well as their applications in supercapacitors.Additionally,the superiorities of MOFs-related materials are highlighted,while major challenges or opportunities for future research on them for electrochemical supercapacitors have been discussed and displayed,along with extensive experimental experiences.

K_(x)C_(y) phase induced expanded interlayer in ultra-thin carbon toward full potassium-ion capacitors

Carbonaceous materials have been regarded as highly promising anode candidates for potassium storage with their cost-effectiveness and environmental benignity.However,low specific capacity and difficulty in large-scale synthesis largely hinder their further development.Herein,a thermal-induced potassium–carbon alloy phase(K_(x)C_(y))with the expanded interlayer spacing strategy is first put forward.Through in situ high-temperature X-ray diffraction,a K_(2)C_(2) phase is evoked by thermal energy during the in-situ carbonization process of carbon quantum dots intermediate derived from potassium-containing precursors,whereas no lithium or sodium–carbon alloy phase is observed from lithium/sodium-containing precursors.The asobtained ultra-thin carbon nanosheets achieve adjustable layer spacing,preparation in bulk,delivering reversible potassium storage of 403.4 mAh g^(−1) at 100 mA g^(−1) and 161.2 mAh g^(−1) even at 5.0 A g^(−1),which is one of the most impressive K-storage performances reported so far with great potential application.Furthermore,the assembled potassium-ion hybrid capacitor by combining the impressive CFMs-900 anode with the three-dimensional framework-activated carbon delivers a high energy-power density of 251.7 Wh kg^(−1) at 250Wkg^(−1) with long-term stability.This study opens a scalable avenue to realize the expanded interlayer spacing,which can be extended to other multicarboxyl potassium salts and can provide approach for the design of high-performance carbon anode materials for potassium storage.

High-yield red phosphorus sponge mediated robust lithium-sulfur battery

Although lithium-sulfur(Li-S)batteries with high specific energy exhibit great potential for next-generation energy-storage systems,their practical applications are limited by the growth of Li dendrites and lithium polysulfides(LiPSs)shuttling.Herein,a highly porous red phosphorus sponge(HPPS)with well distributed pore structure was efficiently prepared via a facile and largescale hydrothermal process for polysulfides adsorption and dendrite suppression.As experimental demonstrated,the porous red phosphorus modified separator with increased active site greatly promotes the chemisorption of LiPSs to efficiently immobilize the active sulfur within the cathode section,while Li metal anode activated by Li_(3)P interlayer with abundant ionically conductive channels significantly eliminates the barrier for uniform Li^(+)permeation across the interlayer,contributing to the enhanced stability for both S cathode and Li anode.Mediated by the HPPS,long-term stability of 1,200 h with minor voltage hysteresis is achieved in symmetric cells with Li_(3)P@Li electrode while Li-S half-cell based on HPPS modified separator delivers an outperformed reversibility of 783.0 mAh·g^(−1)after 300 cycles as well as high-rate performance of 694.5 mAh·g^(−1)at 3 C,which further boosts the HPPS tuned full cells in practical S loading(3 mg·cm^(−2))and thin Li3P@Li electrode(100μm)with a capacity retention of 71.8%after 200 cycles at 0.5 C.This work provides a cost-effective and metal free mediator for simultaneously alleviating the fundamental issues of both S cathode and Li anode towards high energy density and long cycle life Li-S full batteries.