Reconfiguring the Electronic Structure of Heteroatom Doped Carbon Supported Bimetallic Oxide@Metal Sulfide Core–Shell Heterostructure via In Situ Nb Incorporation toward Extrinsic Pseudocapacitor

Abstract

High‐energy‐density battery‐type materials have sparked considerable interest as supercapacitors electrode; however, their sluggish charge kinetics limits utilization of redox‐active sites, resulting in poor electrochemical performance. Here, the unique core–shell architecture of metal organic framework derived N–S codoped carbon@CoxSy micropetals decorated with Nb‐incorporated cobalt molybdate nanosheets (Nb‐CMO4@CxSyNC) is demonstrated. Coordination bonding across interfaces and π–π stacking interactions between CMO4@CxSy and N and, S–C can prevent volume expansion during cycling. Density functional theory analysis reveals that the excellent interlayer and the interparticle conductivity imparted by Nb doping in heteroatoms synergistically alter the electronic states and offer more accessible species, leading to increased electrical conductivity with lower band gaps. Consequently, the optimized electrode has a high specific capacity of 276.3 mAh g−1 at 1 A g−1 and retains 98.7% of its capacity after 10 000 charge–discharge cycles. A flexible quasi‐solid‐state SC with a layer‐by‐layer deposited reduced graphene oxide /Ti3C2TX anode achieves a specific energy of 75.5 Wh kg−1 (volumetric energy of 1.58 mWh cm−3) at a specific power of 1.875 kWh kg−1 with 96.2% capacity retention over 10 000 charge–discharge cycles.

Electronic Structure Engineered Heteroatom Doped All Transition Metal Sulfide Carbon Confined Heterostructure for Extrinsic Pseudocapacitor

“…Generally, the b‐value of 0.5 represents the total charges stored on the electrode by a diffusion‐controlled process; however, b = 1 represents the charge storage by the capacitive process. [ 42,43 ] The fitted outcomes of the α ‐/ γ ‐MnS@Co x S y @N, SC‐5 electrodes show that the value of b is equal to 0.85, with an R 2 value of 0.9995, indicating that the charge stored on the electrodes from surface capacitive as well as diffusion‐controlled processes (Figure 3c). The b‐value is close to 1, representing the faradaic charge storage with fast surface redox reactions.…”

“…Before the fabrication of QFEPs, the charges on both electrodes were balanced by mass balancing of electrodes using the below equation. [2,43]…”

“…The following equation was used to calculate the specific capacity of electrodes. [2,42,43] Specific capacity (Q s ) = I × Δt m × 3.6 (8)…”

“…Using the following equations, the specific capacitance (C s ), and volumetric capacitance (C V ), as well as the corresponding energy and power of the electrodes and QFEPs device, were determined. [2,42,43] Specific capacitance (C s ) = I × Δt m × ΔV…”

“…Where, the applied current is I, the discharge time is t, and the operational potential window is V. The following equation was used to determine the energy efficiency of the QFEPs device. [2,42,43] Energy efficiency = E discharge × 100∕E charge (14) where E discharge and E charge are energy densities of the discharging and charging curves.…”