Zinc-ion Hybrid Supercapacitors Research Articles

Hierarchical porous carbon with abundant N/O doping as an anode for zinc ion hybrid supercapacitors

Aqueous zinc-ion hybrid supercapacitors (ZISCs) known for their affordability, stability, and high energy density represent innovative energy storage devices. Porous carbon is usually used as the cathode material of ZISCs, and its structure significantly affects the dual performance of high power density and energy density of ZISCs. Herein, a one-pot carbonization strategy is proposed, eliminating the need for templates, additional heteroatom compounds, and activation processes. By precisely controlling the temperature to optimize the structure and electrochemical performance of carbon materials, we successfully synthesized hierarchical porous carbon materials (NOPC-800) with a high specific surface area of 1545.7 mg, featuring dual doping of 12.3 at% nitrogen and 13.35 at% oxygen. The self-doping of abundant nitrogen and oxygen atoms facilitates the chemical adsorption of ions and accelerates pseudocapacitive reaction kinetics. Leveraging these advantages, ZISCs were assembled using NOPC-800 as the positive electrode and zinc as the negative electrode, showcasing remarkable performance: a specific capacity of up to 121.9 mAh g, an energy density of 97.5 Wh kg, and a power density of up to 16000 W kg. Remarkably, NOPC-800 maintained an excellent capacity retention of 94.9% after 10,000 cycles at a current density of 10 A g. This research paves an innovative and feasible path for the design and advancement of novel heteroatom-rich carbon cathodes.

Peri‐Xanthenoxanthene‐Based Covalent Organic Frameworks for High‐Performance Aqueous Zn‐Ion Hybrid Supercapacitors

Aqueous zinc‐ion hybrid supercapacitors (Zn‐HSCs) are promising devices for sustainable and efficient energy storage. However, they suffer from a limited energy density compared to lithium‐ion batteries. This limitation can be overcome by developing novel electrode materials, with covalent organic frameworks (COFs) standing out as a particularly intriguing option. Herein, peri‐xanthenoxanthene (PXX) has been integrated for the first time into a COF scaffold to take advantage of its straightforward synthesis, chemical stability, π‐conjugated backbone, and heteroatom content endowing reversible redox reactions at low potentials. Two novel hexagonal COFs have been designed and synthesized by tethering of a PXX‐diamine unit having a C2 symmetry with two distinct tris‐aldehydes acting as C3‐symmetric cornerstones, i.e., triformyl benzene (TFB) and triformylphloroglucinol (Tp), ultimately yielding COF PXX(PhNH2)2‐TFB and COF PXX(PhNH2)2‐Tp, respectively. As cathodes in Zn‐HSCs, COF PXX(PhNH2)2‐Tp exhibits a remarkable specific capacitance, energy, and power densities (237 F g−1, 106.6 Wh kg−1, and 3.0 kW kg−1, respectively), surpassing those of COF PXX(PhNH2)2‐TFB (109 F g−1, 49.1 Wh kg−1, and 0.67 kW kg−1). Importantly, both COFs display outstanding long‐term stability, over 5000 charge/discharge cycles, with capacitance retention >92%. These findings underscore the potential of PXX‐based COFs as high‐performance cathode materials for HSCs, thereby offering a promising new avenue for energy storage technologies.

Highly tri-heteroatom doped porous carbon for aqueous and flexible quasi-solid-state zinc-ion hybrid supercapacitors

Porous carbon, a promising low-cost cathode material for zinc-ion hybrid supercapacitors (ZHSCs), is plagued by inferior hydrophilicity and insufficient active sites during charge/discharge process. Herein, a highly tri-heteroatom co-doped porous carbon material (HSACNS0.5) was prepared from the pyrolysis of Humulus scandens combining heteroatom doping. The high oxygen, nitrogen and sulfur content (total about 29.2 %) combining superior specific surface area (1505.9 m2 g−1) and hierarchical porous structure leads to superior wettability and abundant active sites, resulting in rapid kinetic behaviors and considerable ions adsorption capacity. Furthermore, the high content of heteroatoms provides extra pseudocapacitance. Consequently, the aqueous ZHSC based on HSACNS0.5 displays an excellent specific capacitance of 414.4 F g−1 at 0.5 A g−1, and energy density of 187.4 Wh kg−1 at a power density of 810 W kg−1. Moreover, the HSACNS0.5 cathode based flexible quasi-solid-state ZHSC operates well at different bending states. Even at a high mass loading of 17.3 mg cm−2, the ZHSC shows cycling stability and a superior areal capacitance of 4.27 F cm−2.

Cation-driven self-assembly of core–shell covalent organic frameworks@Ti3CN MXene nanospheres for high-performance aqueous zinc-ion hybrid supercapacitors

Rechargeable aqueous Zn-ion hybrid supercapacitors (ZISCs) with the superiorities of high theoretical capacity, low redox potential and aqueous electrolytes with superior ionic conductivity (∼1 S cm−1) are promising energy storage systems. However, a primary concern persists due to the absence of cathode materials with both high energy densities and satisfactory cycling stability for robust ZISCs. In this study, we design a spherical core–shell covalent organic frameworks@Ti3CN MXene (CM-P) cathode via a cation-driven electrostatic self-assembly strategy. The CM-P with the constructed heterostructures shows both well-organized pore channels and excellent intrinsic conductivity, facilitating fast accessibility to intrinsic redox-active sites (such as C = O and N), and promoting effective ion diffusion characterized by low energy barriers. Consequently, the CM-P cathodes demonstrate excellent electrochemical performance, featuring an ultrahigh specific capacity of 260 mAh/g at 0.1 A, a high-rate capability with 68 % retention at 1 A/g, and long-term cycling stability. First-principle calculations elucidate that the enhanced charge-storage mechanism relies on the heterostructures of CM-P, accelerating ion adsorption/diffusion and electron transfer. Furthermore, the assembled CM-P//Zn ZISCs devices show a high energy density of 217.1 Wh kg−1 along with power density of 22.3 kW kg−1. This work provides an innovative approach to design COFs-based heterostructures for advanced ZISCs.

High-Performance Zinc-Ion Hybrid Supercapacitor from Guilin Sanhua Liquor Lees-Derived Carbon Materials.

Aqueous zinc-ion hybrid supercapacitors (ZHSCs) have attracted considerable attention because they are inexpensive and safe. However, the inadequate energy densities, power densities, and cycling performance of current ZHSC energy-storage devices are impediments that need to be overcome to enable the further development and commercialization of this technology. To address these issues, in this study, we prepared carbon-based ZHSCs using a series of porous carbon materials derived from Sanhua liquor lees (SLPCs). Among them, the best performance was observed for SLPC-A13, which exhibited excellent properties and a high-surface-area structure (2667 m2 g-1) with abundant micropores. The Zn//SLPC-A13 device was assembled by using 2 mol L-1 ZnSO4, SLPC-A13, and Zn foil as the electrolyte, cathode, and anode, respectively. The Zn//SLPC-A13 device delivered an ultrahigh energy density of 137 Wh kg-1 at a power density of 462 W kg-1. Remarkably, Zn//SLPC-A13 retained 100% of its specific capacitance after 120,000 cycles of long-term charge/discharge testing, with 62% retained after 250,000 cycles. This outstanding performance is primarily attributed to the SLPC-A13 carbon material, which promotes the rapid adsorption and desorption of ions, and the charge-discharge process, which roughens the Zn anode in a manner that improves reversible Zn-ion plating/stripping efficiency. This study provides ideas for the preparation of ZHSC cathode materials.

Fallen autumn leaves – The source of highly porous carbon for Zn-ion hybrid supercapacitors

Over the years, many sophisticated synthetic two-dimensional (2D) carbon materials have become increasingly popular for supercapacitors, e.g. zinc-ion hybrid supercapacitors (ZHSC) due to their ordered structure and high energy density. Additionally, ZHSC is a very demanding device, where finding efficient materials is challenging and the energy storage mechanism remains unclear. Biomass-derived carbon materials exhibit many drawbacks due to their impurities and defective structure, low stability and poor capacitance. In this study, a ZHSC was assembled via carbonization and activation of leaves collected from city streets and utilized as a cathode material. The AC650_Zn-foil presented a high specific capacitance of 95 F·g-1 and a high energy density of 86 W·h·kg−1 at 210 W·kg−1. Furthermore, a superior power density of 40,960 W·kg−1 at 33 W·h·g−1 was presented compared to other investigated materials. In addition, we identified the processes that occurred in the following device, which demonstrated a mechanism that determines the migration of Zn ions, as well as the chemical reactions involved in Zn ions.

Zinc-ion hybrid supercapacitors with hierarchically N-doped porous carbon electrodes and ZnSO4/ZnI2 redox electrolyte exhibit boosted energy density

Zinc-ion hybrid capacitors (ZIHCs) with high energy density is commercial need as energy storing devices, but facile preparation is still a challenge. Herein, we proposed a combined strategy for preparation of ZIHCs with high performance. For this purpose, a nanoemulsion assembly approach with Pluronic F127 as structure-directing agent, 1, 3, 5-trimethylbenzene as pore-expanding agent, polydopamine as carbon and nitrogen source, was used to synthesize hierarchically N-doped porous carbon spheres (N-HNCSs). The optimized sample of N-HNCS-1 exhibited uniform size of 150nm, hierarchically porous structure, large surface area (705.46 m2 g-1), and N-doping amount of 6.51%. These properties were beneficial for the transportation of the electrolyte ions resulted in that the N-HNCS-1 electrode displayed superior electrochemical performance with specific capacity of 142 mAh g-1. Furthermore, the Zn//ZnSO4 + ZnI2//N-HNCS-1 ZIHCs achieves an exceptionally high energy density of 347.7Whkg-1, which is 3-fold higher than that of Zn//ZnSO4//N-HNCS-1 ZIHCs. To elucidate this outstanding performance, we investigate the mechanisms involved, including Zn2+ deposition/stripping, SO42-/I- adsorption/desorption, Zn4SO4(OH)6⋅0.5H2O precipitation/dissolution, and redox reactions relating to iodine ions. The incorporation of ZnI2 redox-electrolyte significantly enhanced the energy density by providing prominent pseudocapacitance via the faradaic reaction. Therefore, the high performance of Zn//ZnSO4 + ZnI2//N-HNCS-1 ZIHCs is attributed to the introduction of nitrogen (N) species, advantageous 3D carbonaceous framework, and redox reactions triggered by adding zinc iodide (ZnI2) into the aqueous zinc sulfate (ZnSO4) electrolyte. This groundbreaking research opens up possibilities for the development of high-energy ZIHCs, and advancements in energy storage technology.

Self-adhesive, freeze-tolerant, and strong hydrogel electrolyte containing xanthan gum enables the high-performance of zinc-ion hybrid supercapacitors

Hydrogel electrolyte is an ideal candidate material for flexible energy storage devices due to its excellent softness and conductivity properties. However, challenges such as the inherent mechanical weakness, the susceptibility to be frozen in low-temperature environments, and the insufficiency of hydrogel-electrode contact persist. Herein, a “Multi in One” strategy is employed to effectively conquer these difficulties by endowing hydrogels with high strength, freeze-resistance, and self-adhesive ability. Multiple hydrogen bond networks and ion crosslinking networks are constructed within the hydrogel electrolyte (PVA/PAAc/XG) containing polyvinyl alcohol (PVA), acrylic acid (AAc), and xanthan gum (XG), promoting the enhanced mechanical property, and the adhesion to electrode materials is also improved through abundant active groups. The introduction of zinc ions provides the material with superior frost resistance while also promoting electrical conductivity. Leveraging its multifunction of superior mechanical strength, anti-freeze property, and self-adhesive characteristic, the PVA/PAAc/XG hydrogel electrolyte is employed to fabricate zinc ion hybrid supercapacitors (ZHS). Remarkably, ZHS exhibits outstanding electrochemical performance and cycle stability. A remarkable capacity retention rate of 83.86 % after 10,000 charge-discharge cycles can be achieved at high current densities, even when the operational temperature decreases to −60 °C, showing great potential in the field of flexible energy storage devices.

Graphene nanoribbons on three-dimensional carbon nanomaterials for high-performance flexible zinc-ion hybrid supercapacitors

The rational design of electrodes is crucial for the performance and practical applications of flexible zinc-ion hybrid supercapacitors (ZIHS). In this paper, we have developed an easy strategy to design electrodes based on current collectors with vertically aligned nanohole arrays on their surfaces. Zinc nanosheet arrays were deposited on a porous aluminum oxide/aluminum (AAO) film to form a Zn@AAO anode. Graphene nanoribbons (GR) unzipped for carbon nanotubes were coated on a unique three-dimensional carbon pre-coated AAO (CAAO) film to form a GR@CAAO composite cathode. After assembling with ZnSO4/gelatin gel electrolyte, a quasi-solid Zn@AAO//GR@CAAO ZIHS with a potential of 1.6 V was obtained. The as-prepared ZIHS exhibits an areal capacitance of 156 mF cm−2 at 0.25 mA cm−2 and a high energy density of 56 μW h cm−2 at 0.202 mW cm−2, an excellent flexibility as well as long cycle life.

Synergistic effects of defects and surface engineering in Ni-Co metal oxides to improve the high performance of Zn-ion hybrid supercapacitors

NiCo2O4 (NCO) is an auspicious pseudocapacitor material for high energy density zinc-ion hybrid supercapacitors (ZHSCs), but its low intrinsic conductivity and significant volume expansion seriously hinder its electrochemical performance. Here, we develop a nitrogen (N) doped and oxygen-vacancy-rich (Ov) NiCo oxide nanolines grown in-situ on the carbon cloth (CC) named N-Ov-NCO@CC. The morphology and structure of N-Ov-NCO@CC were characterized by XRD, XPS, EPR, SEM and TEM. It can be clearly observed that N-Ov-NCO@CC nanowires are composed of many tiny nanoparticles, and this unique structure provides abundant gaps at the microscopic scale, providing ample sites for the attachment of electrolyte ions. Due to N-functionalization, synergistic effects of doping, defect and surface engineering are realized. As a result, N-Ov-NCO@CC exhibits significantly enhanced electrochemical performance. The N-Ov-NCO@CC single electrode exhibits a high capacitance of 993.0 F/g (496.5C/g) at 1 A/g and excellent cycle stability with a capacitance retention rate of 98 % after 5000 cycles. In addition, the assembled N-Ov-NCO@CC//Zn-ZHSC operates stably in the voltage range of 1.2–2.0 V. A high specific capacitance of 484.4 F/g is available at current densities of 1 A/g. In addition, it still has a high cycle life with a capacitance retention rate of 97.1 % after 10,000 cycles and a high specific energy/power (50.3 Wh/kg at 300.2 W/kg). Density function theory (DFT) verification shows that N-Ov-NCO has higher conductivity than Ov-NCO and pristine NCO, which is conducive to improving electrochemical performance. This work provides a new idea for developing stable electrode materials for new ZHSCs.

Evaluation of zinc-ion hybrid super-capacitor based on chemically activated (KOH/H3PO4) ground nutshell biochar

In the realm of advancing energy storage technologies, the efficacy of natural biomass sources in mitigating environmental constraints has gained prominence. This study delves into the evolving landscape of energy storage devices, specifically batteries, super-capacitors, and the nascent domain of zinc-ion hybrid super-capacitors (ZIHSC). The focus centers on biomass-derived highly activated carbon, a burgeoning field of research esteemed for its diversity, environmental compatibility, distinctive structural attributes, and unique surface characteristics. This investigation presents a comparative analysis of activated carbons derived from ground nutshell (GS) in the context of ZIHSC applications. Emphasis is placed on the significance of a straightforward biochar synthesis process and subsequent chemical activation. The activated biochar, denoted as GS-H3PO4 and synthesized using H3PO4, exhibits a discernibly higher Brunauer Emmett Teller (B.E.T.) surface area when juxtaposed with pre-carbonized ground nutshell (GS-Biochar).The ZIHSC cell incorporating GS-H3PO4 manifests noteworthy energy density metrics, registering at 50.28 Wh Kg−1 (100 W Kg−1) and 11 Wh Kg−1 (2 kW Kg−1). Additionally, it demonstrates a specific capacitance of 199 F g−1 (2 mV s−1). These findings underscore the promising potential of H3PO4-derived activated carbon in optimizing cathode performance for Zinc-ion hybrid super-capacitors. This study contributes to the growing understanding of biomass-derived materials, offering insights into the nuanced interplay between synthesis methods and electrochemical properties, crucial for advancing sustainable energy storage solutions.

Polymer-mediated vacancy defects of graphene sheets as high-performance cathode materials for aqueous zinc-ion hybrid supercapacitors

The electrochemical behavior of graphene sheets in energy storage system is closely related to its electronic structures. Specifically, structural vacancy defects can expose more active sites and enhance the electrochemical performance. However, it is still a challenging problem to realize valid defect regulation on improving the reaction kinetics of electrode materials. Herein, vacancy-defective graphene sheets were constructed through the thermal mediated method via intercalation of polyacrylonitrile nanofibers. The vacancy defects were generated from the NH3 gas resulting from polymer decomposition at gradient carbonization temperature. The obtained composites of the graphene sheets and carbon nanofibers demonstrate that the vacancy defects benefit to charge transport, allowing more electrons to pass through the interlayered structure, and enhance the adsorption capacitance during the reversible electrochemical process. In addition, the as-assembled Zn ion hybrid supercapacitors exhibit a high energy density of 129.9 Wh kg−1 and outstanding cyclic stability (99.8 % after 10,000 cycling). The confined polymer-mediated thermal modification strategy can afford abundant vacancy defective sites and exhibit promising outlook for constructing high-performance graphene-based electrode materials for Zn ion hybrid supercapacitors.

Hydrophilic polyanionic hydrogel electrolyte for anti-freezing and bending resistant zinc-ion hybrid supercapacitors

Zinc-ion hybrid supercapacitors (ZHSCs) have been widely considered as promising candidates for flexible electrochemical energy storage devices. The key challenge is to develop hydrogel electrolytes with high hydrophilicity, anti-freezing, bending resistance, and stable interface with electrodes. This study reported a hydrogel electrolyte system that can meet the above functions, in which the zincophilic and negatively charged SO3−, migratable Na+, abundant hydrophilic functional groups, gum xanthan, and porous architecture could effectively promote the electrochemical performance of ZHSCs. ZHSCs with such hydrogel electrolytes not only exhibited good low-temperature performance but also showed excellent bending resistance ability. A high specific capacitance could be kept after a long air-working lifespan over 10,000 cycles under a wide operation voltage of 1.85 V at −10 °C. Furthermore, flexible ZHSCs could maintain the capacitance retention of 93.18% even after continuous 500 bends at an angle of 180°. The designed hydrogel electrolytes could be also used for other electrochemical energy storage devices with anti-freezing and bending resistance by changing electrolyte salt.

Rational design of integrated high-performance flexible zinc-ion hybrid supercapacitors based on electroactive biomass regulated graphene oxide

Rational design of integrated high-performance flexible zinc-ion hybrid supercapacitors based on electroactive biomass regulated graphene oxide

Evolving non-aggregated ZIF-8 nanoparticles into hierarchically porous hollow carbon nanofibers for high-performance flexible zinc-ion hybrid supercapacitor

Zinc-ion hybrid supercapacitors are garnering widespread interest in wearable energy storage devices due to their high power density, intrinsic safety and cost-effectiveness. However, the primary obstacle to their progress lies in the scarcity of cathode materials that concurrently demonstrate excellent flexibility and high energy density. Herein, we deliberately design a coaxial electrospinning ZIF-8 derived hollow carbon nanofiber film electrode (C-PAN(ZIF-8)@PVP) to achieve high-performance flexible ZHSCs. The distinctive configuration of C-PAN(ZIF-8)@PVP electrode comprises a shell of homogeneously distributed ZIF-8 derived porous carbon nanoparticles, which are bound together by N-doped carbon fibers derived from polyacrylonitrile (PAN), and a channel through the fiber created by the decomposition of polyvinylpyrrolidone (PVP). This unique architecture coupled with N, O co-doping bestows ample electrolyte infiltration, complete exposure of active sites, and a rapid pathway for electron conduction, resulting in facilitated ion diffusion kinetics, abundant active sites and enhanced electronic conductivity of the C-PAN(ZIF-8)@PVP electrode. As a result, the assembled ZHSC delivers a high reversible capacity of 116 mAh g−1 at 0.1 A g−1 and remarkable capacity retention of 100% over 4000 cycles at 5 A g−1. Moreover, it exhibits exceptional mechanical flexibility, capable of delivering stable output under arbitrary deformation. The intricate structural design strategy offers valuable insights for the development of high-performance electrode materials.

Dendrite-free zinc anode enabled by zwitterionic organic hydrogel electrolytes for high-voltage zinc-ion hybrid capacitors

Aqueous zinc-ion hybrid supercapacitors (ZIHC) have been widely researched due to their inherent high safety, low cost, and high power. However, the low operating voltage of aqueous electrolytes, H2O-induced side reactions, and intractable dendrites severely compromise the energy output and durability of ZIHC. Herein, a freeze-tolerant zwitterionic organic hydrogel electrolyte (PSAMOHE) was constructed for high-voltage flexible ZIHC. The hydrogen bonding between ethylene glycol and water inhibited the formation of ice crystals, preventing the electrolyte from freezing at −40 °C. Concurrently, the hydrophilic PSAMOHE mitigated harmful side reactions and achieved a wide electrochemical stability window (2.2 V) by anchoring water molecules. In addition to exhibiting exceptional interface adhesion and mechanical adaptability, PSAMOHE with charged functional groups effectively facilitated ion migration, diminished the desolvation energy barrier of hydrated Zn2+, and induced uniform Zn deposition. By combining these advantages, the assembled flexible ZIHC exhibited a battery-level specific capacity of 269.1 mAh/g (at 0.5 A/g), impressive environmental adaptability, and excellent mechanical adaptability. Impressively, the ZIHC maintained 89.5 % of the initial capacity and obtained a dendrite-free Zn anode after 14,000 cycles of charge and discharge. This study provides valuable insights into the exploration of hydrogel electrolyte engineering for high-performance zinc-based flexible energy storage devices.

Stable Flexible Electronic Devices under Harsh Conditions Enabled by Double-Network Hydrogels Containing Binary Cations.

Hydrogels are increasingly used in flexible electronic devices, but the mechanical and electrochemical stabilities of hydrogel devices are often limited under specific harsh conditions. Herein, chemically/physically cross-linked double-network (DN) hydrogels containing binary cations Zn2+ and Li+ are constructed in order to address the above challenges. Double networks of chemically cross-linked polyacrylamide (PAM) and physically cross-linked κ-Carrageenan (κ-CG) are designed to account for the mechanical robustness while binary cations endow the hydrogels with excellent ionic conductivity and outstanding environmental adaptability. Excellent mechanical robustness and ionic conductivity (25 °C, 2.26 S·m-1; -25 °C, 1.54 S·m-1) have been achieved. Utilizing the DN hydrogels containing binary cations as signal-converting materials, we fabricated flexible mechanosensors. High gauge factors (resistive strain sensors, 2.4; capacitive pressure sensors, 0.82 kPa-1) and highly stable sensing ability have been achieved. Interestingly, zinc-ion hybrid supercapacitors containing the DN hydrogels containing binary cations as electrolytes have achieved an initial capacity of 52.5 mAh·g-1 at a current density of 3 A·g-1 and a capacity retention rate of 82.9% after 19,000 cycles. Proper working of the zinc-ion hybrid supercapacitors at subzero conditions and stable charge-discharge for more than 19,000 cycles at -25 °C have been demonstrated. Overall, DN hydrogels containing binary cations have provided promising materials for high-performance flexible electronic devices under harsh conditions.

Pyrrolic-N/C = O cooperative assisted in hollow porous carbon with ultra-high electrochemical performance for Zn-ion hybrid supercapacitors

The development of high-energy–density advanced Zinc-ion hybrid supercapacitors (ZIHSs) shows significant potential, yet it remains a complex undertaking due to its heavy reliance on physical Zn2+ adsorption and the limitations imposed by insufficient cathodes. This study employs a rich in C = O and pyrrolic-N functional groups hollow porous carbon derived from cattail leaves as a cathode material for high-energy-power ZIHSs. The proposed charge storage mechanism involves the assimilation of opposite charge carriers, coupled with a multi-electron redox response, which was investigated by Ex-situ experiments and density functional theory (DFT) simulations. This process entails the alternating binding of Zn2+ and SO42− at designated active sites, along with strong relationships between Zn2+ and electronegative C = O/pyrrolic-N motifs, leading to the creation of C-O-Zn-N-C bonds. Consequently, the aqueous ZIHSs constructed with this hollow porous carbon cathode exhibit outstanding performance metrics. These include an impressive energy density of 128 Wh kg−1, a discharge specific capacity of 149 mAh/g at 10 A/g, a superb power density of 1188 W kg−1, and an extraordinary long-term lifespan, retaining 95 % of its initial capacity after 10,000 cycles. Importantly, the strategy of augmenting energy storage through chemical adsorption capability modulation can be applied to other carbon materials.

Efficient and eco-friendly preparation of N/P/O co-doped porous carbon electrode for zinc-ion hybrid supercapacitors by laser carbonization

The incorporation of heteroatoms into carbon materials confers advantages in the development of electrode materials for zinc-ion supercapacitors with superior electrochemical performance. However, the conventional carbonization process requires a large thermal power input and is characterized by complexity, high costs, and lengthy reaction times. In this work, the phytic acid-doped polypyrrole (P-PPy) was carbonized via laser irradiation to synthesize N, P, O co-doped porous carbon (P-NOPC), wherein phytic acid served as the source of phosphorus and oxygen, while PPy served as the porous carbon precursor and nitrogen source. The formation of porous carbon can provide a large specific surface area for ion adsorption. The doping of heteroatoms improves the hydrophilicity of porous carbon electrodes and also improves the chemisorption capacity of carbon materials. The aqueous zinc-ion hybrid supercapacitor (ZHSC) based on 0.6P-NOPC9 positive electrode and zinc foil negative electrode has a discharge capacity of 148.0 mAh g−1 in a voltage window of 0.2–1.8 V at 0.1 A g−1, a high energy density (118.2 Wh kg−1) and long cycle life (capacity retention of 98.5% after 10,000 cycles). In addition, the capacity retention of the flexible quasi-solid-state ZHSC is 97.8% after 10,000 cycles. This study can provide a reference for the feasible design of porous carbon electrodes with high performance.

Multilayer Core-Sheath Wires with Radially Aligned N-Doped Carbon Nanohole Arrays for Boosting Energy Storage in Zinc-Ion Hybrid Supercapacitors.

Aqueous zinc-ion hybrid supercapacitors (ZHSCs) with the characteristics of low cost, long cycle stability, and good safety have been regarded as potential candidates for wearable energy storage applications. Herein, we reasonably designed a unique binder-free nitrogen-doped (N-doped) porous carbon@TiO2@Ti multilayer core-sheath wire (N-CTNT), which has vertical N-doped carbon nanoholes radially aligned on the wire surface. The unique structure and nitrogen dopants of N-CTNTs have facilitated zinc deposition on N-CTNT to form a hierarchical and robust zinc-carbon composite (Zn@N-CTNTs). A wire-shaped ZHSC was constructed with N-CTNTs and Zn@N-CTNTs as cathode and anode electrodes, respectively. The as-prepared ZHSC has an outstanding specific capacitance of 488 mF cm-2 at 1 mA cm-2. This hybrid supercapacitor also exhibits an excellent energy density of 211 μW h cm-2, good rate performance, and long cycle stability with a capacity retention rate of 90.4% after 16,000 cycles.