MIL-100(V) derived porous vanadium oxide/carbon microspheres with oxygen defects and intercalated water molecules as high-performance cathode for aqueous zinc ion battery

The development of aqueous zinc ion battery cathode materials with high capacity and high magnification is still a challenge.Herein,porous vanadium oxide/carbon(p-VO_(x)@C,mainly VO_(2) with a small amount of V_(2)O_(3)) core/shell microspheres with oxygen vacancies are facilely fabricated by using a vanadium-based metal-organic framework(MIL-100(V)) as a sacrificial template.This unique structure can improve the conductivity of the VO_(x),accelerate electrolyte diffusion,and suppress structural collapse during circulation.Subsequently,H_(2)O molecules are introduced into the interlayer of VO_(x) through a highly efficient in-situ electrochemical activation process,facilitating the intercalation and diffusion of zinc ions.After the activation,an optimal sample exhibits a high specific capacity of 464.3 mA h g^(-1) at0.2 A g^(-1) and 395.2 mA h g^(-1) at 10 A g^(-1),indicating excellent rate performance.Moreover,the optimal sample maintains a capacity retention of about 89.3% after 2500 cycles at 10 A g^(-1).Density functional theory calculation demonstrates that the presence of oxygen vacancies and intercalated water molecules can significantly reduce the diffusion barrier for zinc ions.In addition,it is proved that the storage of zinc ions in the cathode is achieved by reversible intercalation/extraction during the charge and discharge process through various ex-situ analysis technologies.This work demonstrates that the p-VO_(x)@C has great potential for applications in aqueous ZIBs after electrochemical activation.

Facile anodization approach derived low-crystalline NiCoeOH/NiCoOOH composite films for ultra-high areal capacity and mass loading supercapacitors

The design of supercapacitor materials with both high areal capacity(C)and high mass loading is vitally important for enhancing energy density(E).Herein,we prepared a NiCosingle bondOH/NiCoOOH composite film consisting of NiCosingle bondOH/NiCoOOH nanosheets on an expanded graphite paper(EGP)by using a facial anodization method.The as-prepared NiCosingle bondOH/NiCoOOH film exhibits ultra-high C of 11 mA·h·cm^(-2)at a mass loading of 165 mg·cm^(-2),high rate capability of 71%and excellent cycling stability of 95%after 12000 cycles.The outstanding performance is ascribed to the low-crystalline feature of the NiCosingle bondOH/NiCoOOH nanosheets,and the synergistic effect of the NiCosingle bondOH and NiCoOOH phases and high conductive porous EGP.An aqueous asymmetric supercapacitor,assembled with the NiCosingle bondOH/NiCoOOH on EGP and Fe_(2)O_(3)on EGP as positive-and negative-electrode,respectively,shows a highest E of 3.8 mW·h·cm^(-2)at a power density(P)of 4 mW·cm^(-2)and a maximum P of 107 mW·cm^(-2)at an E of 2.7 mW·h·cm^(-2).

Polypyrrole/nylon membrane composite film for ultra-flexible allsolid supercapacitor

Developing high-performance electrode material with excellent flexibility still remains a big challenge.Herein,we report a simple interfacial polymerization method to fabricate interconnected polypyrrole(PPy)on a commercial nylon membrane(NM).Owing to the special and uniform microstructure of PPy/NM composite film,the free-standing electrode shows a maximal specific capacitance of 2911.4 mF cm^(-2) at 1mA cm^(-2) and superior capacitance retention of 88.7% after charge/discharge for 10,000 cycles.The symmetric all-solid supercapacitor assembled by the PPy/NM composite film exhibits outstanding cyclic stability(capacitance retention of 92.4% after 5000 cycles)and excellent flexibility(capacitance decreasing by 3.3% after bending around a rod with a diameter of 9mm for 1000 times).The results indicate that the PPy/NM composite film has great potential for high performance flexible supercapacitors.

Significantly enhanced thermoelectric performance of flexible PEDOT nanowire film via coating Te nanostructures

A free-standing and highly conductive poly(3,4-ethylenedioxythiophene)(PEDOT)nanowire(NW)film was used as a working electrode for electrodepositing tellurium(Te).By adjusting the electrodeposition time,the thermoelectric(TE)performance of the free-standing hybrid filmwas optimized.The maximum power factor of 240.0 μWm^(-1) K^(-2)(with the electrical conductivity of 561.4 S cm^(-1) and the Seebeck coefficient of 65.4 μVK^(-1))was obtained from a hybrid film electrodeposited for 7 h,which was 8 times higher than that of the pristine PEDOT NW film.In addition,the electrical conductivity of the film almost did not change even after being bent for 400 times around a rod with radius of 4 mm,indicating an excellent flexibility.This work offers a facile approach to prepare multilayered TE films,and desirable combination of excellent flexibility,high electrical conductivity,and facile process scalability makes the free-standing PEDOT NW film particularly promising for portable and flexible electronics.

Facile preparation of poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate)/Ag2Te nanorod composite films for flexible thermoelectric generator

In this work,poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS)coated silver telluride(PCeAg2Te)nanorods were prepared by a wet-chemical method using the PEDOT:PSS coated tellurium(PCeTe)nanorods as the templates.Flexible PCeAg2Te nanocomposite film on polyethersulfone(PES)substrate was prepared through vacuum filtration followed by mechanical pressing process.An optimal PCeAg2Te nanocomposite film showed a maximum power factor of 143.3 mW/mK^(2) at room temperature and 221.7 μW/mK^(2 ) at 373 K.The electrical conductivity of the PCeAg2Te composite film decreased by3.3%after bending for 1000 times around a rod with a radius of 5 mm.An eight-leg thermoelectric generator assembled with the optimal PCeAg2Te nanocomposite film generated a maximum output power and output density of 209.4 nW and 141.5 mW/cm^(2) at a temperature gradient of 30.3 K.This work provides a facile method to prepare thermoelectric materials for flexible thermoelectric generators.