Solvothermal Synthesis and Pyrolysis Toward Heteroatom‐Doped Carbon Microspheres for Zinc‐Ion Hybrid Capacitors

Abstract

Heteroatom‐doped porous carbon materials have investigated to promote the energy density of zinc‐ion hybrid capacitors (ZICs). Yet, the quest for high‐performance carbon materials or cathodes brings to light the question of which dopants facilitate fast energy storage kinetics and various types of pseudocapacitive reactions. Investigation of carbon materials with precise quantitative dopants as the key variable represents an effective appropriate approach to comprehending the intricate role of dopants in energy storage areas. Here, a straightforward solvothermal strategy is demonstrated for a variety of pristine and iron‐incorporated polymer microspheres, used as precursors for durable spherical carbons intended for cathode applications in ZICs. The strategy effectively governs the incorporation of dopants within the carbon materials, whilewhile maintaining consistent morphology, microtexture, and pore structure across different carbon variations. The synergistic effect of various dopants enhance the pseudocapacitance and facilitate the ion storage process. In consequence, the optimal cathode delivers considerable capacity (178.8 mAh g−1 at 0.5 A g−1), good energy density (120.2 Wh kg−1 at 336 W kg−1), and excellent cycling stability (101.5% capacity retention at 35 000 cycles). The demonstration showcases a viable method for crafting carbon materials with precise dopants to accommodate the zinc anode, thus enabling high‐capacity and high‐energy ZICs.

Enabling Wasted A4 Papers as a Promising Carbon Source to Construct Partially Graphitic Hierarchical Porous Carbon for High-Performance Aqueous Zn-Ion Storage

“…These results clearly authenticated the excellent robustness, reliable invertibility, and small charge S3), such as Zn//BN-ZIC-3 (115.7 Wh kg −1 ), 22 Zn//CSGC-700 (111.1 Wh kg −1 ), 31 Zn// LDC (97.6 Wh kg −1 ), 32 Zn//3DPC (156 Wh kg −1 ), 35 Zn// HHPC-6 (117.6 Wh kg −1 ), 38 Zn//PHCA (129.3 Wh kg −1 ), 45 Zn//N-HCNbs-6 (109 Wh kg −1 ), 66 Zn//NPCN 750 (143 Wh kg −1 ), 67 Zn//PCNs-2 (119 Wh kg −1 ), 68 and Zn//CFe0.2 (120.2 Wh kg −1 ). 69 Significantly, for the A4CA3-based ZIHSC device, a notable capacity of 117.7 mA g −1 with a capacity sustenance of 93.8% and nearly 100% Coulombic efficiency was achieved after 10,000 long-term charge−discharge cycles at a high current density of 10 A g −1 (Figure 4h), further affirming the eminent durability of the A4CA3 cathode. Figure 5a presents the CV profiles of the Zn//A4CA3 device at different scan rates, where the observation of the rectanglelike shape with visible lumps disclosed that the Zn 2+ storage mechanism comprised double-layer capacitance corresponding to fast ion adsorption/desorption of carbon cathode and pesudocapacitance corresponding to reversible Zn 2+ deposition/stripping of Zn anode, 22,45 and the CV curves exhibited no obvious distortion even at a high scan rate of 200 mV s −1 , signaling the speedy electrochemical kinetics and high electron/ion transportation rate because of interconnected hierarchical porosity with the graphitic structure for a short/ fast transfer route and quality hydrophilicity for high interfacial accessibility.…”

“…The diameter of the semicircle represented the charge transfer resistance ( R ct ), and the R ct values for A4CA1, A4CA2, A4CA3, and A4CA4 were calculated to be 33.37, 17.32, 14.12, and 21.50 Ω, respectively, implying the smallest charge transfer resistance of the A4CA3 cathode, agreeing with the IR data in Figure e. As depicted in Figure g, the multiple virtues of high specific capacity, charming rate capability, and extensive potential range of 0.2 to 1.8 V endowed the Zn//A4CA3 device an uppermost energy density of 190.4 Wh kg –1 under a power density of 99.3 W kg –1 at 0.1 A g –1 with a reserved energy density of 83.1 Wh kg –1 under 18 kW kg –1 at 20 A g –1 , outstripping that of Zn//A4CA1 (71.7 Wh kg –1 ), Zn//A4CA2 (145.4 Wh kg –1 ), and A4CA4 (183.0 Wh kg –1 ), and even outweighing many reported aqueous ZIHSC devices constructed by different kinds of carbon materials (as listed in Table S3), such as Zn//BN-ZIC-3 (115.7 Wh kg –1 ), Zn//CSGC-700 (111.1 Wh kg –1 ), Zn//LDC (97.6 Wh kg –1 ), Zn//3DPC (156 Wh kg –1 ), Zn//HHPC-6 (117.6 Wh kg –1 ), Zn//PHCA (129.3 Wh kg –1 ), Zn//N-HCNbs-6 (109 Wh kg –1 ), Zn//NPCN 750 (143 Wh kg –1 ), Zn//PCNs-2 (119 Wh kg –1 ), and Zn//CFe0.2 (120.2 Wh kg –1 ) . Significantly, for the A4CA3-based ZIHSC device, a notable capacity of 117.7 mA g –1 with a capacity sustenance of 93.8% and nearly 100% Coulombic efficiency was achieved after 10,000 long-term charge–discharge cycles at a high current density of 10 A g –1 (Figure h), further affirming the eminent durability of the A4CA3 cathode.…”