Ultrahigh Areal Capacitance Research Articles

Lithiophilic and conductive V2O3/VN nanosheets as regulating layer for high-rate, high-areal capacity and dendrite-free lithium metal anodes

• A partially porous V 2 O 3 /VN nanosheet was prepared by nitridation reaction. • The V 2 O 3 /VN nanosheet with lithiophilic and conductive can improve lithium plating/stripping behavior. • The V 2 O 3 /VN-Li anode has superior long cycling stability under the high rate and areal capacity. Lithium metal batteries (LMBs) possess high energy and power density, while the dendrite growth on lithium metal anodes prevents its practical application. And most of the current modification methods only improve from a single aspect, which is difficult to achieve ideal effect of suppressing dendrite in the long cycling with high rate and areal capacity. Herein, a conductive and lithiophilic patch-like V 2 O 3 /VN nanosheet as regulating layer is designed on surface of lithium metal anode (V 2 O 3 /VN-Li) to hinder the dendrite growth. The superior lithiophilicity, fast electron/ion transport of V 2 O 3 /VN nanosheets contribute to a low nucleation overpotential and uniform lithium deposition, thus greatly suppressing the dendrite formation at high current density with repeated plating/stripping. As a result, the V 2 O 3 /VN-Li anode achieves ultra-long life for over 2000 h under ultra-high current density and areal capacity (30 mA cm −2 , 30 mAh cm −2 ). The modified strategy of multifunctional regulating layer on the surface of lithium metal anodes can open a new direction for the realization of high-power and high-energy–density LMBs.

A Stretchable Ionic Conductive Elastomer for High‐Areal‐Capacity Lithium‐Metal Batteries

Developing high‐areal‐capacity and dendrite‐free lithium (Li) anodes is of significant importance for the practical applications of the Li‐metal secondary batteries. Herein, an effective strategy to stabilize the high‐areal‐capacity Li electrodeposition by modifying the Li metal with a stretchable ionic conductive elastomer (ICE) is demonstrated. The ICE layer prepared via an instant photocuring process shows a promising Li+‐ion conductivity at room temperature. When being used in Li‐metal batteries, the thin ICE coating (~0.27 μm) acts as both a stretchable constraint to minimize the Li loss and a protective layer to facilitate the uniform flux of Li ions. With this ICE‐modifying strategy, the reversibility and cyclability of the Li anodes under high‐areal‐capacity condition in carbonate electrolyte are significantly improved, leading to a stable Li stripping/plating for 500 h at an ultrahigh areal capacity of 20 mAh cm−2 in commercial carbonate electrolyte. When coupled with industry‐level thick LiFePO4 electrodes (20.0 mg cm−2), the cells with ICE‐Li anodes show significantly enhanced rate and cycling capability.

A Lithium-Metal Anode with Ultra-High Areal Capacity (50 mAh cm−2) by Gridding Lithium Plating/Stripping

Lithium dendrites, “dead lithium”, infinite volume change and fragile solid electrolyte interphase (SEI) appear indefinitely during Li plating/stripping process, which severely resist the practical application of lithium metal batteries (LMBs). Herein, by a functionalized framework, a phosphorized copper mesh as support skeleton, the lithium plating/stripping has been gridded into zoning effect, thus a desired lithium anode with excellent performance and practical application significance can be achieved. The framework-based lithium anode showed multi-functions with many advantages: enhancing lithium affinity, mitigating volume expansion, improving the current distributions, and inducing uniform deposition of Li+. Thus, a highly reversible and dendrite-free lithium anode under large capacity could be successfully realized, which has been verified by operando optical dynamic test and COMSOL simulation. As expected, symmetric-cell displays low overpotential (~210 mV) at ultra-high current density of 20 mA cm−2 and long lifespan (>1600 h) at ultra-high areal capacity of 50 mAh cm−2, moreover, full-cell delivers high cycling stability (2 C, 500 cycles) and outstanding rate performance with a lower polarization.

SiOx embedded in N-doped carbon nanoslices: A scalable synthesis of high-performance anode material for lithium-ion batteries

SiOx is a promising anode material for lithium-ion batteries owing to its smaller volume expansion and longer lifespan than silicon. However, its development is severely hampered by the sluggish reaction kinetics and large volume changes. Herein, a facile and scalable synthesis of exfoliated N-doped carbon nanoslices supported SiOx (SiOx/NCS) is developed by a melamine assisted ball milling and annealing procedure. The principle of melamine in exfoliating graphite is demonstrated by contrast experiments and theoretical calculations. It is found NCS acts as matrix to enhance the reaction kinetics and accommodate the volume changes which contributes to the significant improvements of cycling performance and rate capability. The SiOx/NCS anode exhibits ultrastable cycling performance (∼900 mAh g−1 over 600 cycles at 1 A g−1) and superior rate capability (565 mAh g−1 at 5 A g−1). At a high mass loading of 3.3 mg cm−2, an ultrahigh areal capacity of 2.4 mAh cm−2 is obtained after 200 cycles. Moreover, the potential application of SiOx/NCS anode in LIBs is also confirmed by the good performance of SiOx/NCS//NCM111 full cells.

Mass Transport Behaviors in Graphene and Polyaniline Heterostructure–Based Microsupercapacitors

The development of miniaturized energy storage components with high areal performance for emerging electronics depends on scalable fabrication techniques for thick electrodes and an in‐depth understanding of the intrinsic properties of materials. Based on the coprecipitation behavior of electrically exfoliated graphene and reduced graphene oxide–templated polyaniline (PANi) nanoflake, this work develops a simple, green, low‐cost, and scalable drop‐casted technique to easily fabricate uniform thick electrodes (up to 80 μm) on various substrates. Through using a direct laser writing process, planar microsupercapacitors can be readily attained. As‐fabricated flexible all‐solid‐state microsupercapacitors exhibit an ultrahigh areal capacitance of 172 mF cm−2 at 0.1 A cm−2 and excellent cycling stability of 91% capacitance retention over 2000 cycles at a high current density of 1.0 A cm−2. Furthermore, based on the electrochemical quartz crystal microbalance research result, the pseudocapacitance contribution is mostly provided by the adsorption/desorption of SO42− anions during the protonation process of PANi. This work offers a simple strategy toward superior‐performance micro‐sized energy devices and a new perspective to understand the origin of the capacitance of composites and heterostructures.

Polymer Molecular Engineering Enables Rapid Electron/Ion Transport in Ultra‐Thick Electrode for High‐Energy‐Density Flexible Lithium‐Ion Battery

AbstractFlexible lithium‐ion batteries (LIBs) with high energy density are of urgent need for the ever‐increasing flexible and wearable electronic equipments, but limited by the low areal loading of active materials in traditional electrodes with lamellar structure. It is still a great challenge to solve the sluggish electron/ion transport problem caused by increasing the areal loading of active materials. Herein, a kind of ethylene vinyl acetate copolymer (EVA) is proposed to provide flexible supports and ion channels for ultra‐thick flexible LFP/CNT/EVA cathode and LTO/CNT/EVA anode, thereby achieving high energy density and all flexible LIBs. LFP/CNT/EVA shows a ternary homogeneous structure formed by the entanglement of EVA chains and CNT on LFP, which attributes to LFP content up to 80wt% and adjustable thickness from 20 to 460 µm. In sharp contrast to previous studies LFP/CNT/EVA delivers basically the constant specific capacity of ≈160 mAh g−1 at a 0.1 C rate with the thickness increasing, thus achieving ultrahigh areal capacity up to 4.56 mAh cm−2. A flexible full LIBs based on LFP/CNT/EVA and LTO/CNT/EVA is demonstrated and exhibits favorable cycle performance under an alternant flat and bending state. Those findings are supposed to open new avenues for designing high‐energy‐density flexible LIBs for future wearable energy storage devices.

Deep Eutectic Solvent‐Induced Polyacrylonitrile‐Derived Hierarchical Porous Carbon for Zinc‐Ion Hybrid Supercapacitors

AbstractHierarchical porous carbon that possesses large surface area and high porosity has become an important electrode material for supercapacitors. However, some unavoidable issues like complex approach and environmental pollution involved in traditional chemical activation restrict the sustainable development of carbons. Herein, a green, low‐cost, and safe urea‐zinc chloride deep eutectic solvent (DES) is proposed to prepare polyacrylonitrile derived three‐dimensional carbon nanosphere (D‐PC). Specially, the D‐PC efficiently accelerates electrolyte ions migration and enhances charge storage due to its interconnected ionic pathways and large accessible active surfaces. When employing the D‐PC as positive electrode of zinc‐ion hybrid supercapacitors, a high specific capacitance of 261.5 F g−1 at 0.2 A g−1 along with a cycling stability of 91.3 % after 10000 cycles at 5 A g−1. Meanwhile, such device holds the maximum energy/power density of 93.9 Wh kg−1/16.7 kW kg−1 at 0.2 A g−1/20 A g−1, respectively. Thanks to the unique physicochemical properties of as‐obtained D‐PC, an ultrahigh areal capacitance of 2.2 F cm−2 also can be achieved at a mass loading of 23 mg cm−2. The satisfying structure and performance highlight the potential of DESs in the design of functional carbons.

Toward Practical High-Areal-Capacity Aqueous Zinc-Metal Batteries: Quantifying Hydrogen Evolution and a Solid-Ion Conductor for Stable Zinc Anodes.

The hydrogen evolution in Zn metal battery is accurately quantified by in situ battery-gas chromatography-mass analysis. The hydrogen fluxes reach 3.76 mmol h-1 cm-2 in a Zn//Zn symmetric cell in each segment, and 7.70 mmol h-1 cm-2 in a Zn//MnO2 full cell. Then, a highly electronically insulating (0.11 mS cm-1 ) but highly Zn2+ ion conductive (80.2 mS cm-1 ) ZnF2 solid ion conductor with high Zn2+ transfer number (0.65) is constructed to isolate Zn metal from liquid electrolyte, which not only prohibits over 99.2% parasitic hydrogen evolution but also guides uniform Zn electrodeposition. Precisely quantitated, the Zn@ZnF2 //Zn@ZnF2 cell only produces 0.02 mmol h-1 cm-2 of hydrogen (0.53% of the Zn//Zn cell). Encouragingly, a high-areal-capacity Zn@ZnF2 //MnO2 (≈3.2 mAh cm-2 ) full cell only produces maximum hydrogen flux of 0.06 mmol h-1 cm-2 (0.78% of the Zn//Zn cell) at the fully charging state. Meanwhile, Zn@ZnF2 //Zn@ZnF2 symmetric cell exhibits excellent stability under ultrahigh current density and areal capacity (10 mA cm-2 , 10 mAh cm-2 ) over 590 h (285 cycles), which far outperforms all reported Zn metal anodes in aqueous systems. In light of the superior Zn@ZnF2 anode, the high-areal-capacity aqueous Zn@ZnF2 //MnO2 batteries (≈3.2 mAh cm-2 ) shows remarkable cycling stability over 1000 cycles with 93.63% capacity retained at ≈100% Coulombic efficiency.

A Replacement Reaction Enabled Interdigitated Metal/Solid Electrolyte Architecture for Battery Cycling at 20 mA cm-2 and 20 mAh cm-2.

Metal anodes represent as a prime choice for the coming generation rechargeable batteries with high energy density. However, daunting challenges including electrode volume variation and inevitable side reactions preclude them from becoming a viable technology. Here, a facile replacement reaction was employed to fabricate a three-dimensional (3D) interdigitated metal/solid electrolyte composite electrode, which not only provides a stable host structure for buffering the volume change within the composite but also prevents side reactions by avoiding the direct contact between active metal and liquid electrolyte. As a proof-of-concept demonstration, a 3D interdigitated zinc (Zn) metal/solid electrolyte architecture was fabricated via a galvanic replacement reaction between Zn metal foil and indium (In) chloride solution followed by electrochemical activation, featuring the interdigitation between metallic Zn and amorphous indium hydroxide sulfate (IHS) with high Zn2+ conductivity (56.9 ± 1.8 mS cm-1), large Zn2+ transference number (0.55), and high electronic resistivity [(2.08 ± 0.01) × 103 Ω cm]. The as-designed Zn/IHS electrode sustained stable electrochemical Zn plating/stripping over 700 cycles with a record-low overpotential of 8 mV at 1 mA cm-2 and 0.5 mAh cm-2. More impressively, it displayed cycle-stable performance with low overpotential of 10 mV under ultrahigh current density and areal capacity (20 mA cm-2, 20 mAh cm-2), which outperformed all the reported Zn metal electrodes in mild aqueous electrolyte. The fabrication of interdigitated metal/solid electrolyte was generalized to other metal pairs, including Zn/Sn and Zn/Co, which provide inspiration for next-generation Zn metal batteries with high energy density and reversibility.

Multitasking MXene Inks Enable High-Performance Printable Microelectrochemical Energy Storage Devices for All-Flexible Self-Powered Integrated Systems.

The future of mankind holds great promise for things like the Internet of Things, personal health monitoring systems, and smart cities. To achieve this ambitious goal, it is imperative for electronics to be wearable, environmentally sustainable, and safe. However, large-scale manufacture of self-sufficient electronic systems by exploiting multifunctional materials still faces significant hurdles. Herein, multitasking aqueous printable MXene inks are reported as an additive-free high-capacitance electrode, sensitive pressure-sensing material, highly conducting current collector, metal-free interconnector, and conductive binder. By directly screen printing MXene inks, MXene-based micro-supercapacitors (MSCs) and lithium-ion microbatteries (LIMBs) are delicately fabricated on various substrates. The as-prepared MSCs exhibit ultrahigh areal capacitance of 1.1 F cm-2 and the serially connected MSCs offer a record voltage of 60V. The quasi-solid-state LIMBs deliver a robust areal energy density of 154μWhcm-2 . Furthermore, an all-flexible self-powered integrated system on a single substrate based on the multitasking MXene inks is demonstrated through seamless integration of a tandem solar cell, the LIMB, and an MXene hydrogel pressure sensor. Notably, this integrated system is exceptionally sensitive to body movements with a fast response time of 35ms. Therefore, this multipurpose MXene ink opens a new avenue for powering future smart appliances.

Dendrite‐free lithium and sodium metal anodes with deep plating/stripping properties for lithium and sodium batteries

AbstractAlthough lithium (Li) and sodium (Na) metals can be selected as the promising anode materials for next‐generation rechargeable batteries of high energy density, their practical applications are greatly restricted by the uncontrollable dendrite growth. Herein, a platinum (Pt)–copper (Cu) alloy‐coated Cu foam (Pt–Cu foam) is prepared and then used as the substrate for Li and Na metal anodes. Owing to the ultrarough morphology with a three‐dimensional porous structure and the quite large surface area as well as lithiophilicity and sodiophilicity, both Li and Na dendrite growths are significantly suppressed on the substrate. Moreover, during Li plating, the lithiated Pt atoms can dissolve into Li phase, leaving a lot of microsized holes on the substrate. During Na plating, although the sodiated Pt atoms cannot dissolve into Na phase, the sodiation of Pt atoms elevates many microsized blocks above the current collector. Either the holes or the voids on the surface of Pt–Cu foam what can be extra place for deposited alkali metal, what effectively relaxes the internal stress caused by the volume exchange during Li and Na plating/stripping. Therefore, the symmetric batteries of Li@Pt–Cu foam and Na@Pt–Cu foam have both achieved long‐term cycling stability even at ultrahigh areal capacity at 20 mAh cm−2.

Redox-active p-phenylenediamine functionalized reduced graphene oxide film through covalently grafting for ultrahigh areal capacitance Zn-ion hybrid supercapacitor

Graphene film electrode usually suffers from undesirable electrochemical performance due to its agglomeration effect and electrical double layer storage mechanism. Here, the p-phenylenediamine (PPD) is adopted as a redox-active spacer to simultaneously alleviate these problems. Specifically, PPD is introduced into the interlayer of graphene film, which is favorable to enhance the interlayer distance and consequently expose more ion accessible area. Moreover, the redox-active nature of PDD endows graphene film with tremendous pseudocapacitance by a reversible redox reaction with electrolyte ions. Benefiting from these advantages, the fabricated Zn-ion hybrid supercapacitors (ZHSs) by combing the PPD functionalized reduced graphene oxide (RGO) film (RGO@PPD (6:7)) positive electrode and Zn foil negative electrode displays remarkable areal capacitance of 3012.5 mF cm−2 and a high energy densities of 1.1 mWh cm−2 at power densities of 0.8 mW cm−2. This organic molecule covalent bond decoration approach opens up a new way for improving the electrochemical performance of the graphene film for advanced ZHSs.

Graphene/Multi-Walled Carbon Nanotubes Hybrid Films with Ultrahigh Areal Capacitance and Energy Density for High-Performance Wearable Energy Storage

Graphene/Multi-Walled Carbon Nanotubes Hybrid Films with Ultrahigh Areal Capacitance and Energy Density for High-Performance Wearable Energy Storage

Hexagonal petal-like cobalt oxide nanowire arrays encapsulated by MOF-derived Co/N-codoped carbon for boosting electrochemical capacitor behaviour

A novel core–shell hetero-structured electrode (NF@CoO@Co/N–C) is designed and synthesized via a “anchor-etch-calcine” process for boosting electrochemical capacitor behaviour. The unique structure endows NF@CoO@Co/N–C with ultrahigh areal capacitances and good rate capability.

Scalable electrode materials with nanoporous current collector shells for supercapacitors with ultrahigh areal and volumetric capacitances

Supercapacitors are characterized by high power density, but a bottleneck exists regarding their limited energy density due to the conflict between achieving a high mass loading and high specific capacitance with the current structural design.

Functional and structural insight into lignocellulosic fibers for high-areal-capacity lithium–sulfur batteries

A novel way of absorbing sulfur species by a vascular system of lignocellulosic fibers and hollow VO2achieved ultrahigh areal capacity, and the extraordinary adsorption behavior was characterized byoperandoRaman spectroscopy.

Dual modulation of the morphology and electric conductivity of NiCoP on nickel foam by Fe doping as a superior stability electrode for high energy supercapacitors.

Nickel-cobalt bimetallic phosphide (NiCoP) is a potential electrode material for supercapacitors on account of its high theoretical specific capacitance. However, its practical application is restricted because of its relatively poor cycling stability and rate performance. Herein, we constructed self-standing NiCoP nanowires and Fe doped NiCoP nanoarrays with different iron ion concentrations on nickel foam (Fe-NiCoP/NF-x%, x = 4, 6.25, 12.5, 25) as a positive electrode for asymmetric supercapacitors (ASCs). The morphological result reveals that the nanostructure of the material evolves from nanowires to nanosheets with the iron doping concentration, and the Fe-NiCoP/NF-12.5% nanosheets possess a more stable structure than NiCoP/NF nanowires. The density functional theory analysis implies that the conductivity of the material enhances after Fe doping because of the increased charge density and electron states. The combination of multicomponents and structural advantages endows the optimal Fe-NiCoP/NF-12.5% electrode with an ultrahigh areal capacitance of 9.93 F cm-2 (2758.34 F cm-3) under 1 mA cm-2, excellent rate capability (82.58% from 1 mA cm-2 to 50 mA cm-2) and superior cycling stability (95.72% retention over 5000 cycles under 20 mA cm-2), and the areal capacitance of Fe-NiCoP/NF-12.5% is 2.27 times higher than that of the pristine NiCoP/NF electrode at 1 mA cm-2. Moreover, the assembled Fe-NiCoP/NF-12.5%//activated carbon ASC device delivers a high energy density of 0.327 mW h cm-2 (60.43 mW h cm-3) at 1.10 mW cm-2 (202.54 mW cm-3). Therefore, this strategy may provide a novel route for the application of NiCoP with its intrinsic advantages in the energy storage field.

Act in contravention: a non-planar coupled electrode design utilizing “tip effect” for ultra-high areal capacity, long cycle life zinc-based batteries

Aqueous zinc-based batteries (ZBBs) have great potential as commercial energy storage devices. However, the poor cycling stability of zinc anode under high areal capacity limits their further application. Herein, a coupled non-planar electrode design achieved by the tailored flat-top pyramid carbon felt (TCF) is proposed for ZBBs, which can effectively increase the zinc deposition sites, adjust the deposition morphology, optimize the current and electrolyte flow velocity distribution and provide necessary space for zinc plating. Interestingly, by utilizing “tip effect”, the coupled TCFs enable precise control of the zinc dendrite growth position, effectively reducing the risk of short circuit. Based on such coupled TCFs, zinc-iodine flow batteries can deliver an ultra-high areal capacity of 240 mAh cm−2 and a superb cycling stability over 300 cycles (areal capacity of 160 mAh cm−2) at a high current density of 40 mA cm−2. Therefore, we provide an effective strategy for high areal capacity zinc anode design, which may promote the development of high energy density and long cycle life ZBBs.

Multilevel structured carbon film as cathode host for Li-S batteries with superhigh-areal-capacity

The commercialization of lithium-sulfur (Li-S) battery could be accelerated by designing advanced sulfur cathode with high sulfur utilization and stable cycle life at a high sulfur loading. To allow the energy density of Li-S batteries comparable to that of commercial Li-ion batteries, the areal capacity of sulfur cathode should be above 4 mA·h·cm−2. In general, a high sulfur loading often causes rapid capacity fading by slowing electron/ion transport kinetics, catastrophic shuttle effect and even cracking the electrodes. To address this issue, herein, a multilevel structured carbon film is built by covering highly conductive CNTs and hollow carbon nanofiber together with carbon layer via chemical vapor deposition. The self-standing carbon film exhibits well-interweaved conductive network, hollow fibrous structure and abundant N, O co-doped active sites, which combine the merits of high electronic conductivity (1200·S·m−1), high porosity and polar characteristic in one host. Benefiting from this attractive multilevel structure, the obtained sulfur cathode based on the carbon film host shows an ultra-high areal capacity of 8.9 mA·h·cm−2 at 0.2 C with outstanding cyclability over 60 cycles. This work shed light on designing advanced sulfur host for Li-S batteries with high areal capacity and high cycle stability, and might make a contribution to the commercialization of Li-S batteries.

Lignin carbon aerogel/nickel binary network for cubic supercapacitor electrodes with ultra-high areal capacitance

It is crucial for energy storage devices to manufacture the thick electrode with high energy and power density. The electrochemical performance of the commercial porous carbon supercapacitor electrode fabricated by traditional methods is highly dependent on the electrode thickness. Therefore, a cost-effective method is required to fabricate thick electrode with high mass loading, high specific capacitance and superior rate performance. Herein an ultra-thick cubic electrode is fabricated based on lignin carbon aerogel/nickel (LCAN) bulk with binary network structure using polymerization under ZnCl2 hypersaline condition. This is an efficient and low-cost route to prepare carbon aerogels without drying under rigorous condition and ZnCl2 is an ideal porogen, activating agent and hard template for LCAN. The precise adjustment of ZnCl2/lignin ratio and the combination of LCAN binary network results in the cubic electrode (thickness up to 4.2 mm), with an ultra-high areal capacitance of 26.6 F cm−2 (63% retained from 1 to 200 mA cm−2), an excellent cycle stability even with high mass loading (∼147 mg cm−2) and myriad shapes. These features represent the highest areal capacitance values reported carbonaceous thick electrodes. With these unique features, this study represents a promising 3D thick electrodes for energy-related devices.