General Synthesis of N-Doped Macroporous Graphene-Encapsulated Mesoporous Metal Oxides and Their Application as New Anode Materials for Sodium-Ion Hybrid Supercapacitors

Abstract

A general method to synthesize mesoporous metal oxide@N-doped macroporous graphene composite by heat-treatment of electrostatically co-assembled amine-functionalized mesoporous silica/metal oxide composite and graphene oxide, and subsequent silica removal to produce mesoporous metal oxide and N-doped macroporous graphene simultaneously is reported. Four mesoporous metal oxides (WO 3−x , Co 3 O 4 , Mn 2 O 3 , and Fe 3 O 4 ) are encapsulated in N-doped macroporous graphene. Used as an anode material for sodium-ion hybrid supercapacitors (Na-HSCs), mesoporous reduced tungsten oxide@N-doped macroporous graphene (m-WO 3−x @NM-rGO) gives outstanding rate capability and stable cycle life. Ex situ analyses suggest that the electrochemical reaction mechanism of m-WO 3−x @NM-rGO is based on Na + intercalation/de-intercalation. To the best of knowledge, this is the first report on Na + intercalation/de-intercalation properties of WO 3−x and its application to Na-HSCs.

Mesopore‐Induced Ultrafast Na+‐Storage in T‐Nb2O5/Carbon Nanofiber Films toward Flexible High‐Power Na‐Ion Capacitors

“…The energy density ( E ) and power density ( P ) are calculated based on the total mass of both active materials using the equations: E = and P = E/t , in which I is the current density (A g −1 ), t is the discharge time (s), and V min and V max correspond to the final and initial discharge voltages ( V ), respectively. The NIC device can achieve a maximum energy density of ≈124 Wh kg −1 , corresponding to a power density of 200 W kg −1 .…”

Synthesis of CuS@CoS2 Double‐Shelled Nanoboxes with Enhanced Sodium Storage Properties

“…Sodium‐ion batteries (SIBs) have aroused increasing interest as a promising candidate for large‐scale electric energy storage in view of their merits in terms of cost and natural abundance compared to the established lithium‐ion battery systems . Developing efficient anode materials is highly desirable to promote the practical implementation of SIBs .…”

Synthesis of Cobalt Sulfide Multi‐shelled Nanoboxes with Precisely Controlled Two to Five Shells for Sodium‐Ion Batteries

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We report the synthesis of cobalt sulfide multishelled nanoboxes through metal-organic framework (MOF)based complex anion conversion and exchange processes.The polyvanadate ions react with cobalt-based zeolitic imidazolate framework-67 (ZIF-67) nanocubes to form ZIF-67/cobalt polyvanadate yolk-shelled particles.T he as-formed yolkshelled particles are gradually converted into cobalt divanadate multi-shelled nanoboxes by solvothermal treatment. [2,[4][5][6][7][8] Among the potential negative electrode materials for SIBs,t ransition metal sulfides (TMSs) are quite attractive because of their rich redox sites,high capacity and enhanced electrical conductivity compared with their oxide counterparts. The as-obtained cobalt sulfide multi-shelled nanoboxes exhibit enhanced sodium-storage properties when evaluated as anodes for sodium-ion batteries.

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“…[9,[14][15][16][17][18] In particular,h ollow structures with complex interiors have drawn significant attention owing to their structure-dependent merits.A sf or sodium storage applications,i ntricate hollow structures exhibit great advantages over simple hollow architectures. [6,7,[23][24][25][26][32][33][34] Given the presence of both thermally and chemically unstable porous frameworks,M OFs can be easily converted into hollow structured materials via pyrolysis or chemical reactions with desirable reagents.A mong different transformation methods,ion-exchange reactions have been shown as an effective tool for structural and compositional transformation of MOFs. [22] As ar esult, av ariety of electrode materials have been fabricated in the form of multi-shelled hollow structures.…”

“…[6,7,[23][24][25][26][32][33][34] Given the presence of both thermally and chemically unstable porous frameworks,M OFs can be easily converted into hollow structured materials via pyrolysis or chemical reactions with desirable reagents.A mong different transformation methods,ion-exchange reactions have been shown as an effective tool for structural and compositional transformation of MOFs. [6,7,[23][24][25][26][32][33][34] Given the presence of both thermally and chemically unstable porous frameworks,M OFs can be easily converted into hollow structured materials via pyrolysis or chemical reactions with desirable reagents.A mong different transformation methods,ion-exchange reactions have been shown as an effective tool for structural and compositional transformation of MOFs.…”