Conductive Polypyrrole Coated Hollow NiCo₂O₄ Microspheres as Anode Material with Improved Pseudocapacitive Contribution and Enhanced Conductivity for Lithium‐Ion Batteries

Abstract

Conductive polypyrrole (PPy) coated urchin-like hollow NiCo 2 O 4 (NCO) porous microspheres (NCO@PPy) were synthesized by an easy and cost-effective method. The NCO@PPy shows improved cycling stability and rate capability in comparison with the pure NiCo 2 O 4 when used as anode material for lithium-ion batteries. In order to undersatnd the improvement of electrochemical performance of NCO@PPy, kinetic parameters and the lithium storage mechanism are investigated by EIS spectra and sweep voltammetry measurements. The sweep-rate-dependent CV (cyclic voltammetry) curves demonstrate an ever-increasing redox capacitive-controlled lithium storage originating from both, the hierarchical hollow structure and the effect of the PPy coating layer. The apparent Li + ion diffusion coefficient of NCO@PPy and NCO derived from EIS and CV curves indicates that PPy coating layer reduces the charge-transfer resistances and improves the lithium-ion diffusion coefficient.

Unveiling the Impact of the Polypyrrole Coating Layer Thickness on the Electrochemical Performances of LiNi0.5Co0.2Mn0.3O2 in Li–Ion Battery

“…Different from NCM, sample PPy5 exhibits a conspicuous N 1s signal at about 400.0 eV (Figure d). This photoelectron signal is originated from the nitrogen element in the PPy . Combining the analysis of XPS, TEM, Raman and FTIR, it can be reasonably concluded that the PPy was successful coated on the surface of NCM, but did not change the the valence state of cations.…”

“…Two peaks at 476 and 592 cm −1 are assigned to the bending E g and stretching A 1g modes of layered LiMO 2 . [36,37] Different from NCM, two extra broad peaks at around 1350 and 1585 cm −1 observed in the Raman spectrum of PPy5 are ascribed to C=C stretching and the anti‐symmetrical C−N stretching mode of PPy . To further ascertain the presence of PPy, the samples NCM and PPy5 were also characterized by FT‐IR spectroscopy (Figure b).…”

Preparation and Electrochemical Performance of CoSe2−MnSe2 for Application in Lithium‐Ion Batteries

“…The carbon materials including reduced graphene oxide (rGO) and carbon nanotubes (CNT) . Except the methods above, conductive polymer serves multiple functions in the composite when they are used in anode such as polypyrrole (PPy) and polyaniline …”

In Operando analysis of the charge storage mechanism in a conversion ZnCo2O4 anode and the application in flexible Li-ion batteries

“…In this line, some ternary oxides have been developed, such as ZnCo 2 O 4 , [13][14][15] CoFe 2 O 4 , [16][17][18] and NiCo 2 O 4 . [19][20][21] Among them, ZnCo 2 O 4 (ZCO) is very promising since conversion and alloy combined charge storage mechanism occurs upon lithiation. This material delivers high specific capacity, theoretically 789 mA h g −1 with 7e − per formula unit ( pfu).…”