Ni0.85 Se hexagonal nanosheets as an advanced conversion cathode for Mg secondary batteries

Mg secondary batteries are promising scalable secondary batteries for next-generation energy storage.However,Mg-storage cathode materials are greatly demanded to construct high-performance Mg batteries.Electrochemical conversion reaction provides plenty of cathode options,and strategy for cathode selection and performance optimization is of special significance.In this work,Ni0.85Se with nanostructures of dispersive hexagonal nanosheets(D-Ni0.85Se)and flower-like assembled nanosheets(F-Ni0.85Se)is synthesized and investigated as Mg-storage cathodes.Compared with F-Ni0.85Se,D-Ni0.85Se delivers a higher specific capacity of 168 mAh g^-1 at 50 mA g^-1 as well as better rate performance,owing to its faster Mg^2+-diffusion and lower resistance.D-Ni0.85Se also exhibits a superior cycling stability over 500cycles.An investigation on mechanism indicates an evolution of Ni0.85Se towards NiSe with cycling,and the Mg-storage reaction occurs between NiSe and metallic Ni^0.The present work demonstrates that advanced conversion-type Mg battery cathode materials could be constructed by soft selenide anions,and the electrochemical properties could be manipulated by rational material morphology optimization.

The Effect of Polymer-Substrate Interaction on the Nucleation Property:Comparing Study of Graphene and Hexagonal Boron Nitride Nanosheets

Hexagonal boron nitride nanosheets （BNNSs） can work as a more efficient nucleating agent for two polyesters compared to graphene. Studies on the crystallization and dewetting processes of two polyesters, poly（butylene succinate） and poly（butylene adipate）, on the two substrate surfaces prove that the interaction between BNNSs and the polyesters is stronger than that between graphene and the polyesters. This strong interaction induces the pre-ordered conformation of molten PBA which has been identified by the in situ FTIR spectra. Thus BNNSs possess higher nucleation property than graphene. Finally, a new polymer-substrate interaction induced nucleation mechanism was proposed to explain the nucleation efficiency difference between graphene and BNNSs.

Design of B/N Co-doped micro/meso porous carbon electrodes from CNF/BNNS/ZIF-8 nanocomposites for advanced supercapacitors

Boron(B)and nitrogen(N)co-doped 3D hierarchical micro/meso porous carbon(BNPC)were successfully fabricated from cellulose nanofiber(CNF)/boron nitride nanosheets(BNNS)/zinc-methylimidazolate framework-8(ZIF-8)nanocomposites prepared by 2D BNNS,ZIF-8 nanoparticles,and wheat straw based CNFs.Herein,CNF/ZIF-8 acts as versatile skeleton and imparts partial N dopant into porous carbon structure,while the introduced BNNS can help strengthen the hierarchical porous superstructure and endow abundant B/N co-dopants within BNPC matrix.The obtained BNPC electrode possesses a high specific surface area of 505.4 m2/g,high B/N co-doping content,and desirable hydrophilicity.Supercapacitors assembled with BNPC-2(B/N co-doped porous carbon with a CNF/BNNS mass ratio of 1꞉2)electrodes exhibited exceptional electrochemical performance,demonstrating high capacitance stability even after 5000 charge-discharge cycles.The devices exhibited outstanding energy density and power density,as well as the highest specific capacitance of 433.4 F/g at 1.0 A/g,when compared with other similar reports.This study proposes a facile and sustainable strategy for efficiently fabrication of rich B/N co-doped hierarchical micro/meso porous carbon electrodes from agricultural waste biomass for advanced supercapacitor performance.