Mesh-like vertical structures enable both high areal capacity and excellent rate capability

In order to balance electrochemical kinetics with loading level for achieving efficient energy storage with high areal capacity and good rate capability simultaneously for wearable electronics,herein,2 D meshlike vertical structures(NiCo_2 S_4@Ni(OH)_2) with a high mass loading of 2.17 mg cm^(-2) and combined merits of both 1 D nanowires and 2 D nanosheets are designed for fabricating flexible hybrid supercapacitors.Particularly,the seamlessly interconnected NiCo_2 S_4 core not only provides high capacity of 287.5 μAh cm^(-2) but also functions as conductive skeleton for fast electron transport;Ni(OH)_2 sheath occupying the voids in NiCo_2 S_4 meshes contributes extra capacity of 248.4 μAh cm^(-2);the holey features guarantee rapid ion diffusion along and across NiCO_2 S_4@Ni(OH)_2 meshes.The resultant flexible electrode exhibits a high areal capacity of 535.9 μAh cm^(-2)(246.9 mAh g^(-1)) at 3 mA cm^(-2) and outstanding rate performance with 84.7% retention at 30 mA cm^(-2),suggesting efficient utilization of both NiCo_2 S_4 and Ni(OH)_2 with specific capacities approaching to their theoretical values.The flexible solid-state hybrid device based on NiCo_2 S_4@Ni(OH)_2 cathode and Fe_2 O_3 anode delivers a high energy density of 315 μWh cm^(-2) at the power density of 2.14 mW cm^(-2) with excellent electrochemical cycling stability.

Redox-active conjugated microporous polymers as electron-accepting organic pseudocapacitor electrode materials for flexible energy storage

Efficient energy storage devices,i.e.pseudocapacitors,are being intensively pursued to address the environmental and energy crises.Most high-performance pseudocapacitors are based on inorganic materials,while organic materials with broader synthetic tunability have attracted increasing interest.Despite recent progress,electron-deficient(n-type)organic pseudocapacitive materials for flexible energy storage are highly demanded yet remain largely unexplored.Here a novel set of n-type perylene diimide(PDI)based conjugated microporous polymers(CMPs),namely,CMP-1,CMP-2 and CMP-3,have been created to integrate excellent desirable characteristics as organic pseudocapacitor electrode materials for flexible energy storage.In light of electron-accepting redox-active sites,hierarchically porous structures,as well as amide-linked networks,the PDI-CMPs electrodes displayed n-type pseudocapacitive behaviors with high capacity(139-205 F g^(-1)at 0.5 A g^(-1)),wide and negative biases(-1.0 to 0 V vs.Ag/AgCl),and long cycling stability.CMP-3 consisting of tetraphenylmethane three-dimensional(3D)building block and PDI units demonstrates not only higher capacitance but also better performance stability because of the higher specific surface area and faster diffusion kinetics as compared to its counterpart CMP-1.Asymmetric supercapacitors(SCs)based on CMP-3 and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate)(PEDOT/PSS)exhibited wider potential window(1.8 V)and higher capacitance(17.4 m F cm^(-2))compared with symmetric SCs based on PEDOT/PSS electrodes.Notably,CMP-3 also demonstrates attractive potentials as the anode for rechargeable Li-ion batteries.The study sheds light on the fundamental understanding of the key structural parameters that determine their electrochemical and transport properties,thus opening a new door for the rational design of efficient and stable n-type organic electrode materials for flexible energy storage applications.

一步碾磨法快速制备红磷嵌入的氮磷共掺杂分级多孔碳复合材料及其储锂性能研究（英文）

红磷因具有高理论储锂容量而成为新一代锂离子电池的重要候选材料,然而其实际应用却受到导电性差以及充放电过程中体积变化大的限制.针对以上问题,本文利用一步碾磨法制备了亚微米/纳米尺度红磷颗粒嵌入的氮、磷原子共掺杂分级多孔碳复合材料(P@NPHPC). NPHPC三维交联的分级多孔结构为红磷负载提供了充足的空间,促进了稳定磷/碳界面的形成,从而有效解决了红磷作为电极材料的不足.基于此, P@NPHPC负极表现出良好的循环稳定性(100 mA g^-1电流密度下, 100次循环后比容量为1120 mA h g^-1)和优越的倍率性能(6400 mA g^-1电流密度下比容量为248 mA h g^-1).本工作对高性能磷/碳复合材料的批量制备及实际应用具有指导意义.

The Jahn-Teller Effect for Amorphization of Molybdenum Trioxide towards High-Performance Fiber Supercapacitor

Amorphous pseudocapacitive nanomaterials are highly desired in energy storage applications for their disordered crystal structures,fast electrochemical dynamics,and outstanding cyclic stability,yet hardly achievable using the state-of-the-art synthetic strategies.Herein,for the first time,high capacitive fiber electrodes embedded with nanosized amorphous molybdenum trioxide(A-MoO_(3)-x)featuring an average particle diameter of~20 nm and rich oxygen vacancies are obtained via a top-down method usingα-MoO_(3)bulk belts as the precursors.The Jahn-Teller distortion in MoO_(6)octahedra due to the doubly degenerate ground state of Mo5+,which can be continuously strengthened by oxygen vacancies,triggers the phase transformation ofα-MoO_(3)bulk belts(up to 30μm long and 500 nm wide).The optimized fibrous electrode exhibits among the highest volumetric performance with a specific capacitance(CV)of 921.5 F cm^(-3)under 0.3 A cm^(-3),endowing the fiber-based weaveable supercapacitor superior CV and EV(energy density)of 107.0 F cm^(-3)and 9.5 mWh cm^(-3),respectively,together with excellent cyclic stability,mechanical robustness,and rate capability.This work demonstrates a promising strategy for synthesizing nanosized amorphous materials in a scalable,cost-effective,and controllable manner.