N-doped hard/soft double-carbon-coated Na3V2(PO4)3 hybrid-porous microspheres with pseudocapacitive behaviour for ultrahigh power sodium-ion batteries

Abstract

Ndoped hard/soft double-carbon-coated Na 3 V 2 (PO 4 ) 3 hybrid-porous microspheres with pseudocapacitive behaviour for ultrahigh power sodium-ion batteries, Electrochimica Acta (2020), doi:

Na$_{4}$Co$_{3}$(PO$_{4}$)$_{2}$P$_{2}$O$_{7}$/NC composite as a negative electrode for sodium-ion batteries

“…5(b), to evaluate the b values for oxidative and reductive peaks, which are found to be around 0.5 and 0.8, respectively. These values suggest for a combination of both diffusive (anodic regime) and pseudo-capacitive (cathodic regime) controlled Na + insertion/de-insertion into the NCPP/NC composite electrode [33,34,42,50].…”

“…These results are presented in the percentage ratio versus the scan rate in Fig. 5(d), which indicate the pseudocapacitive effect for the NCPP/NC composite electrode [33,34,42,50]. Further, the Na + ion diffusion coefficient of the electrode can be determined from the CV using the Randles-Sevcik equation [28,49]:…”

“…In order to enhance the electronic conductivity and reversible capacity, incorporation of carbon matrix in the structure is very effective. Moreover, the dopant heteroatoms (N, B, S, P) can provide pseudo-capacitance, enhance the interlayer distance, as well as generate extrinsic defects to provide more active sites for better Li-/Na-ion storage [30][31][32][33][34]. In fact, N doping introduces donor states near the Fermi level, which can enhance conductivity and reactivity by making the impurity sites active both electronically and chemically [35,36].…”

“…In fact, N doping introduces donor states near the Fermi level, which can enhance conductivity and reactivity by making the impurity sites active both electronically and chemically [35,36]. Therefore, incorporation of N doped carbon matrix in NCPP electrode in the form of composite (NCPP/NC) is expected to increase the conductivity, and help in improving the energy density, rate capacity and cycle life of the Na-ion batteries [32][33][34].…”

Experimental and theoretical investigations of the effect of heteroatom-doped carbon microsphere supports on the stability and storage capacity of nano-Co3O4 conversion anodes for application in lithium-ion batteries

“…[21][22][23][24][25][26][27][28] Among these carbon structures, spherical carbon has maximum packing density, low surface-to-volume ratio and high structural resistance. [29][30][31] However, there is a large scope for further improvements in the performance by introducing defects in carbon matrices, e.g., doping of heteroatoms such as N, B, and S. [32][33][34][35][36][37] These dopant atoms on the surface of carbon materials improve the reactivity, which enhances the lithiation capacity. Additionally, the large atomic size of sulfur atoms can increase the interlayer spacing of the graphitized carbon, create micropores in the carbon matrix and hence improve the charge storage capacity of the carbon material.…”