Polypyrrole-coated α-MoO3 nanobelts with good electrochemical performance as anode materials for aqueous supercapacitors

Abstract

A nanocomposite of molybdenum trioxide (a-MoO 3 ) nanobelts coated with polypyrrole has been fabricated by a simple in situ polymerization route. The structure, morphology and electrochemical performance of the nanocomposite were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and electrochemical measurements. It was found that the polypyrrole acted as a conducting matrix and a coating agent, which effectively improves the conductivity of the MoO 3 nanobelts and inhibits the dissolution of molybdenum ions during cycling. The supercapacitor based on the PPy@MoO 3 nanocomposite as the anode, activated carbon as the cathode and 0.5 M K 2 SO 4 aqueous solution as the electrolyte exhibits better rate capability as well as excellent cycling performance compared to the virginal MoO 3 .

Hierarchical ultrathin NiAl layered double hydroxide nanosheet arrays on carbon nanotube paper as advanced hybrid electrode for high performance hybrid capacitors

“…7e. The device displays a gradually declining behavior during the first 2000 cycles and then the specific capacity almost remains unchanged in the subsequent 3000-cycle test (with a specific capacity retention of 78%), which is comparable to reported HSCs in the literature such as Ni(OH) 2 -MnO 2 //RGO (76% after 3000 cycles) [42], NH 4 NiPO 4 ·H 2 O@PPy-NF//AC (71.6% after 5000 cycles) [43] and PPy@MoO 3 //AC (83% after 600 cycles) [44].…”

Using Polypyrrole Coating to Improve Cycling Stability of NaTi2(PO4)3as an Aqueous Na-Ion Anode

“…This finding is somewhat contradictory to potassium and lithium ion diffusion in previously reported polypyrrole coatings of thicknesses 10-20 nm and 10-12 nm on α-MoO 3 and V 2 O 5 respectively. 27,32 NTP is known to undergo redox reactions with lithium similar to those with sodium, 42 and thus should still present a redox peak if Li + is capable of diffusing through the coating. However, no redox peaks for NTP are seen (Fig.…”

“…Liu et al showed that coating α-MoO 3 with polypyrrole vastly improved the cycling stability of the material by preventing the dissolution of molybdenum ions. 27,31 In addition, although the PPy coating would be expected to be in the neutral state at the redox potentials of α-MoO 3 and thusly provide no enhancement of electronic conductivity, a decrease in charge transfer resistance was reported but no potential mechanism was offered. Similarly, Tang et al showed that coating a composite of V 2 O 5 and multiwalled carbon nanotubes with polypyrrole improved the cycling performance of the material by preventing the dissolution of vanadium ions.…”

“…27,32,[38][39][40] More recently some groups have demonstrated their use in aqueous rechargeable lithium batteries (ARLB). Liu et al showed that coating α-MoO 3 with polypyrrole vastly improved the cycling stability of the material by preventing the dissolution of molybdenum ions.…”

“…One method that has proven useful in the stabilization of aqueous electrode materials is the coating of active material with an electronically conducting or functionalized/conjugated polymer material that is stable in the electrolyte and will serve to protect the active material. 14,27,[31][32][33] Conjugated polymers are linear molecules with partially filled valence or conduction bands. Often based on a series of alternating double and single bonds, which leads to a network of sp 2 -hybridized bonds with the pz-orbitals of the carbon atoms overlapping, leading to the delocalization of charge carriers along the backbone of the polymer chain.…”