Interface Engineering on Cellulose‐Based Flexible Electrode Enables High Mass Loading Wearable Supercapacitor with Ultrahigh Capacitance and Energy Density

Abstract

For practical energy storage devices, a bottleneck is to retain decent integrated performances while increasing the mass loading of active materials to the commercial level, which highlights an urgent need for novel electrode structure design strategies. Here, an active nitrogen‐doped carbon interface with “high conductivity, high porosity, and high electrolyte affinity” on a flexible cellulose electrode surface is engineered to accommodate 1D active materials. The high conductivity of interface favors fast electron transport, while its high porosity and high electrolyte affinity properties benefit ion migration. As a result, the flexible anode accommodated by carbon nanotubes achieves an ultrahigh capacitance of 9501 mF cm−2 (315.6 F g−1) at a high mass loading of 30.1 mg cm−2, and the flexible cathode accommodated by polypyrrole nanotubes realizes a remarkably high capacitance of 6212 mF cm−2 (248 F g−1, 25 mg cm−2). The assembled flexible quasi‐solid‐state asymmetric supercapacitor delivers a maximum energy density of 1.42 mWh cm−2 (2.2 V, 2105 mF cm−2), representing the highest value among all reported flexible supercapacitors. This versatile design concept provides a new way to prepare high performance flexible energy storage devices.

Robust Bioinspired MXene–Hemicellulose Composite Films with Excellent Electrical Conductivity for Multifunctional Electrode Applications

“… − In order to gain insights into the ion resistance, a complex capacitance analysis and frequency response were conducted. The electrodes with hemicellulose show higher phase angle values at low frequencies and lower time constant (τ 0 ), proving better ion response and kinetics (Figure d) . To further quantitatively calculate the ionic resistance ( R i ), the dependence of the imaginary capacitance on the real impedance was correlated (Figure S10).…”

“…The electrodes with hemicellulose show higher phase angle values at low frequencies and lower time constant (τ 0 ), proving better ion response and kinetics ( Figure 4 d). 52 To further quantitatively calculate the ionic resistance ( R i ), the dependence of the imaginary capacitance on the real impedance was correlated ( Figure S10 ). 53 Among them, electrodes with hemicellulose exhibit lower R i values, further proving lower ion transport resistance.…”

Battery-Type-Behavior-Retention Ni(OH)2–rGO Composite for an Ultrahigh-Specific-Capacity Asymmetric Electrochemical Capacitor Electrode

“…The absence of a semicircle in the high-frequency region can be noticed from the magnified plot shown in the inset of Figure 9e, and the resistance value of only 0.11 Ω suggests negligible charge-transfer resistance, as expected for highly conductive materials. 46 It is worth pointing out that the Warburg resistance value is tiny at about 0.49 Ω. The small charge-transfer resistance and the decreased diffusion effect can explain the fast reversible processes at the carbon/electrolyte interface.…”

Interface Engineering of Biomass‐Derived Carbon used as Ultrahigh‐Energy‐Density and Practical Mass‐Loading Supercapacitor Electrodes

“…According to the water contact angle measurement, electrolyte droplet is rapidly absorbed when in contact with NS‐(DA) n ‐Cell electrode, indicating high electrolyte affinity and wettability by virtue of heteroatom‐doped surface chemistry, which further accelerates electrolyte ions transport (Figure S26, Supporting Information). [ 41 ] Therefore, this unique porous pomegranate‐like structure with super hydrophilic surface can guarantee sufficient electrolyte ion transport at high mass loading.…”