High mass loading NiCo_(2)O_(4) with shell-nanosheet/core-nanocage hierarchical structure for high-rate solid-state hybrid supercapacitors

Rational design of advanced structure for transition metal oxides(TMOs) is attractive for achieving high-performance supercapacitors.However, it is hampered by sluggish reaction kinetics, low mass loading, and volume change upon cycling. Herein, hierarchical Ni Co_(2)O_(4) architectures with 2D-nanosheets-shell and 3D-nanocages-core(2D/3D h-NCO) are directly assembled on nickel foam via a facile one-step way.The 2D nanosheets are in-situ generated from the self-evolution of initial NCO nanospheres. This 2D/3D hierarchical structures ensure fast ion/electron transport and maintain the structural integrity to buffer the volume expansion. The 2D/3D h-NCO electrode with an ultrahigh mass loading(30 mg cm^(-2)) achieves a high areal capacity of 4.65 C cm^(-2)(equivalent to 1.29 mAh cm^(-2)) at a current density of 4 mA cm^(-2), and retains 3.7 C cm^(-2) even at 50 mA cm^(-2). Furthermore, the assembled solid-state hybrid supercapacitor yields a high volumetric energy density of 4.25 mWh cm^(-3) at a power density of 39.3 mW cm^(-3), with a high capacity retention of 92.4% after 5000 cycles. Therefore, this work provides a new insight to constuct hierarchical electrodes for energy storage application.

High mass loading Ni_(4)Co_(1)-OH@CuO core-shell nanowire arrays obtained by electrochemical reconstruction for alkaline energy storage

The design of three-dimensional(30)core-shell hetercistructures is an efficient method to achieve high mass specific capacity of electroactive materials under high mass loading.In this work,porous Ni_(4)Co1-0H nanosheets with a mass loading of 7.7 mg·cm^(-2) are obtained by using Ni_(4)Cor(NO_(3))_(2)(0H)_(4) supported on the CuO nanowires as precursors via an unavoidable electrochemically induced phase reconstruction.During the electrochemical reconstruction process,the N03-anions in Ni_(4)Cor(N0_(3))_(2)(0H)_(4) are easily replaced by OH-anions in the electrolyte.The phase reconstruction is accompanied by the decrease of ionic diffusion.:resistance and the increase of pore volume,and the shift of binding energy.The obtained Ni4Co1-0H nanosheets show a high:mass specific capacity of 363.6 mAh·g^(-1) at 5 mA·cm^(-2).The as-fabricated alkaline hybrid supercapacitor and Ni-Zn battery deliver high energy density of 293.1 and 604.9 Wh·kg^(-1),respectively,indicating.excellent alkaline energy storage performance.

Tailoring the electronic conductivity of high-loading cathode electrodes for practical sulfide-based all-solid-state batteries

Sulfide-based all-solid-state batteries(ASSBs)exhibit unparalleled application value due to the high ionic conductivity and good processability of sulfide solid electrolytes(SSEs).Carbon-based conductive agents(CAs)are often used in the construction of electronic conductive networks to achieve rapid electron transfer.However,CAs accelerate the formation of decomposition products of SSEs,and their effects on sulfide-based ASSBs are not fully understood.Herein,the effect of CAs(super P,vaper-grown carbonfibers,and carbon nanotubes)on the performance of sulfide-based ASSBs is investigated under different cathode active materials mass loading(8 and 25 mg⋅cm^(-2)).The results show that under low mass loading,the side reaction between the CAs and the SSEs deteriorates the performance of the cell,while the charge transfer promotion caused by the addition of CAs is only manifested under high mass loading.Furthermore,the gradient design strategy(enrichment of CAs near the current collector side and depletion of CAs near the electrolyte side)is applied to maximize the benefits of CAs in electron transport and reduce the adverse effects of CAs.The charge carrier transport barrier inside the high mass loading electrode is significantly reduced through the regulation of electronic conductivity.Consequently,the optimized electrode achieves a high areal capacity of 5.6 mAh⋅cm^(-2)at high current density(1.25 mA⋅cm2,0.2℃)at 25℃with a capacity retention of 87.85%after 100 cycles.This work provides a promising way for the design of high-mass loading electrodes with practical application value.

Extraordinary Compatibility to Mass Loading and Rate Capability of Hierarchically Porous Carbon Nanorods Electrode Derived from the Waste Tire Pyrolysis Oil

The conversion of waste tire pyrolysis oil(WTPO)into S-doped porous carbon nanorods(labeled as WPCNs)with hierarchical pore structure is realized by a simple template-directed approach.The specific surface area of as-obtained porous carbon nanorods can reach up to 1448 m^(2) g^(−1) without the addition of any activating agent.As the capacitive electrode,WPCNs possess the extraordinary compatibility to capacitance,different electrolyte systems as well as long-term cycle life even at a commercial-level areal mass loading(10 mg cm^(−2)).Besides,only an extremely small capacitance fluctuation is observed under the extreme circumstance(−40 to 80℃),reflecting the excellent high-and low-temperature performance.The relationship between the pore structure and capacitive behavior is analyzed by comparing WPCNs with mesopores-dominated asphalt-derived porous carbon nanorods(APCNs)and micropores-dominated activated carbon.The molecular dynamics simulation further reveals the ion diffusion and transfer ability of the as-prepared carbon materials under different pore size distribution.The total ion flow(NT)of WPCNs calculated by the simulation is obviously larger than APCNs and the N_(T) ratio between them is similar with the experimental average capacitance ratio.Furthermore,this work also provides a valuable strategy to prepare the electrode material with high capacitive energy storage ability through the high value-added utilization of WTPO.

A Silicon Monoxide Lithium-Ion Battery Anode with Ultrahigh Areal Capacity

Silicon monoxide(SiO)is an attractive anode material for next-generation lithium-ion batteries for its ultra-high theoretical capacity of 2680 mAh g−1.The studies to date have been limited to electrodes with a rela-tively low mass loading(<3.5 mg cm^(−2)),which has seriously restricted the areal capacity and its potential in practical devices.Maximizing areal capacity with such high-capacity materials is critical for capitalizing their potential in practi-cal technologies.Herein,we report a monolithic three-dimensional(3D)large-sheet holey gra-phene framework/SiO(LHGF/SiO)composite for high-mass-loading electrode.By specifically using large-sheet holey graphene building blocks,we construct LHGF with super-elasticity and exceptional mechanical robustness,which is essential for accommodating the large volume change of SiO and ensuring the structure integrity even at ultrahigh mass loading.Additionally,the 3D porous graphene network structure in LHGF ensures excellent electron and ion transport.By systematically tailoring microstructure design,we show the LHGF/SiO anode with a mass loading of 44 mg cm^(−2)delivers a high areal capacity of 35.4 mAh cm^(−2)at a current of 8.8 mA cm^(−2)and retains a capacity of 10.6 mAh cm^(−2)at 17.6 mA cm^(−2),greatly exceeding those of the state-of-the-art commercial or research devices.Furthermore,we show an LHGF/SiO anode with an ultra-high mass loading of 94 mg cm^(−2)delivers an unprecedented areal capacity up to 140.8 mAh cm^(−2).The achievement of such high areal capacities marks a critical step toward realizing the full potential of high-capacity alloy-type electrode materials in practical lithium-ion batteries.

Sustainable Lignin-Derived Carbon as Capacity-Kinetics Matched Cathode and Anode towards 4.5 V High-Performance Lithium-Ion Capacitors

The Li-ion capacitors(LICs)develop rapidly due to their double-high features of high-energy density and high-power density.However,the relative low capacity of cathode and sluggish kinetics of anode seriously impede the development of LICs.Herein,the precisely pore-engineered and heteroatomtailored defective hierarchical porous carbons(DHPCs)as large-capacity cathode and high-rate anode to construct high-performance dual-carbon LICs have been developed.The DHPCs are prepared based on triple-activation mechanisms by direct pyrolysis of sustainable lignin with urea to generate the interconnected hierarchical porous structure and plentiful heteroatominduced defects.Benefiting from these advanced merits,DHPCs show the well-matched high capacity and fast kinetics of both cathode and anode,exhibiting large capacities,superior rate capability and long-term lifespan.Both experimental and computational results demonstrate the strong synergistic effect of pore and dopants for Li storage.Consequently,the assembled dual-carbon LIC exhibits high voltage of 4.5 V,high-energy density of 208 Wh kg^(−1),ultrahigh power density of 53.4 kW kg^(−1)and almost zerodecrement cycling lifetime.Impressively,the full device with high mass loading of 9.4 mg cm^(−2)on cathode still outputs high-energy density of 187 Wh kg^(−1),demonstrative of their potential as electrode materials for high-performance electrochemical devices.

High‑Mass‑Loading Electrodes for Advanced Secondary Batteries and Supercapacitors

The growing demand for advanced electrochemical energy storage systems(EESSs)with high energy densities for electric vehicles and portable electronics is driving the electrode revolution,in which the development of high-mass-loading electrodes(HMLEs)is a promising route to improve the energy density of batteries packed in limited spaces through the optimal enlargement of active material loading ratios and reduction of inactive component ratios in overall cell devices.However,HMLEs face significant challenges including inferior charge kinetics,poor electrode structural stability,and complex and expensive production processes.Based on this,this review will provide a comprehensive summary of HMLEs,beginning with a basic presentation of factors influencing HMLE electrochemical properties,the understanding of which can guide optimal HMLE designs.Rational strategies to improve the electrochemical performance of HMLEs accompanied by corresponding advantages and bottlenecks are subsequently discussed in terms of various factors ranging from inactive component modification to active material design to structural engineering at the electrode scale.This review will also present the recent progress and approaches of HMLEs applied in various EESSs,including advanced secondary batteries(lithium-/sodium-/potassium-/aluminum-/calcium-ion batteries,lithium metal anodes,lithium-sulfur batteries,lithium-air batteries,zinc batteries,magnesium batteries)and supercapacitors.Finally,this review will examine the challenges and prospects of HMLE commercialization with a focus on thermal safety,performance evaluation,advanced characterization,and production cost assessment to guide future development.

Ultrahigh “Relative Energy Density” and Mass Loading of Carbon Cloth Anodes for K-Ion Batteries

Mass loading and potential plateau are the two most important issues of potassium(K)-ion batteries(KIBs),but they have long been ignored in previous studies.Herein,we report a simple and scalable method to fabricate acidized carbon clothes(A-CC)as high mass loading(13.1 mg cm−2)anode for KIBs,which achieved a reversible areal-specific capacity of 1.81 mAh cm−2 at 0.2 mA cm−2.Besides,we have proposed the concept of“relative energy density”to reasonably evaluate the electrochemical performance of the anode.According to our calculation method,the A-CC electrode exhibited an ultrahigh relative energy density of 46 Wh m−2 in the initial charge process and remained at 40 Wh m−2 after 50 cycles.Furthermore,we performed the operando Raman spectroscopy(ORS)to investigate the K-ion storage mechanism.We believe that our work might provide a new guideline for the evaluation of anode performance,thereby,opening an avenue for the development of commercial anode.

Construction of Ti_(3)C_(2)T_(x)/WO_(x) heterostructures on carbon cloth for ultrahigh-mass loading flexible supercapacitor

The capacitance loss caused by slow electron and ion migration kinetics in thick electrode with high-mass loading has been regarded as a great challenge in the field of electrochemical energy storage.Herein,we demonstrate a facile electrochemical deposition method for coating the heterostructured Ti_(3)C_(2)T_(x)/WO_(x) onto flexible carbon cloth( Ti_(3)C_(2)T_(x)/WO_(x)@CC).In the Ti_(3)C_(2)T_(x)/WO_(x) heterojunction,the mixed-valence WOx core provides abundant active sites for H+ions accommodation,while Ti_(3)C_(2)Tx shell can not only prevent peeling off the thick WOx but also act as an interconnected conductive network.The Ti_(3)C_(2)T_(x)/WO_(x)@CC flexible electrode with an ultrahigh mass loading of 34.9 mg·cm^(−2) exhibits a high areal capacitance of 5.73 F·cm^(−2) at 5 mA·cm^(−2) and excellent rate capability.Notably,the Ti_(3)C_(2)T_(x)/WO_(x)@CC electrode under such a high mass loading still delivers a gravimetric capacitance of 164 F·g^(−1) and areal capacitance of Ti_(3)C_(2)T_(x)/WO_(x)@CC electrode increases linearly with the WOx mass loading.Furthermore,a symmetrical supercapacitor assembled with Ti_(3)C_(2)T_(x)/WO_(x)@CC electrode exhibits a good areal energy density of 96.8μWh·cm^(−2) at a power density of 1.5 mW·cm^(−2).This work verifies high mass loading of active materials per unit electrode area for charge storage of supercapacitors in limited space,indicating the great potential in the development of commercially available thick metal-oxide film supercapacitors.

Sn-doped BiOCl nanosheet with synergistic H^(+)/Zn^(2+)co-insertion for“rocking chair”zinc-ion battery

The development of insertion-type anodes is the key to designing“rocking chair”zinc-ion batteries.However,there is rare report on high mass loading anode with high performances.Here,{001}-oriented Bi OCl nanosheets with Sn doping are proposed as a promising insertion-type anode.The designs of cross-linked CNTs conductive network,{001}-oriented nanosheet,and Sn doping significantly enhance ion/electron transport,proved via experimental tests and theoretical calculations(density of states and diffusion barrier).The H^(+)/Zn^(2+)synergistic co-insertion mechanism is proved via ex situ XRD,Raman,XPS,and SEM tests.Accordingly,this optimized electrode delivers a high reversible capacity of 194 m A h g^(-1)at 0.1 A g^(-1)with a voltage of≈0.37 V and an impressive cyclability with 128 m A h g^(-1)over 2500 cycles at 1 A g^(-1).It also shows satisfactory performances at an ultrahigh mass loading of 10 mg cm^(-2).Moreover,the Sn-Bi OCl//MnO_(2)full cell displays a reversible capacity of 85 m A h g^(-1)at 0.2 A g^(-1)during cyclic test.

Sub-nanoscale Engineering of MoO_(2) Clusters for Enhanced Sodium Storage

Smart construction of battery-type anodes with high rate and good mechanical properties is significant for advanced sodium ion capacitors(SICs).Herein,a flexible film consisting of MoO_(2) subnanoclusters encapsulated in nitrogen-doped carbon nanofibers(MoO_(2) SCs@N-CNFs)is designed and synthesized via electrospinning toward SICs as anodes.The strong N-Mo interaction guarantees the stable yet uniform dispersion of high loading MoO_(2) SCs(≈40 wt.%)in the flexible carbonaceous substrate.The sub-nanoscale effect of SCs restrains electrode pulverization and improves the Na+diffusion kinetics,rendering better pseudocapacitance-dominated Na+-storage properties than the nanocrystal counterpart.The MoO_(2) SCs@N-CNFs paper with mass loadings of 2.2–10.1 mg cm^(−2) can be directly used as free-standing anode for SICs,which exhibit high reversible gravimetric/areal capacities both in liquid and quasi-solid-state electrolytes.The assembled flexible SICs competitively exhibit exceptional energy density and cycling stability.More significantly,the sub-nanoscale engineering strategy here is promisingly generalized to future electrode design for other electrochemical energy-related applications and beyond.

Nature-inspired porous multichannel carbon monolith:Molecular cooperative enables sustainable production and high-performance capacitive energy storage

The advancement of supercapacitors(SCs)is closely bound up with the breakthrough of rational design of energy materials.Freestanding and thick carbon(FTC)materials with well-organized porous structure is promising SC electrode delivering high areal capacitive performance.However,controllable and sustainable fabrication of such FTC electrode is still of great challenges.Inspired by natural honeycombs with cross-linked multichannel structure,herein,an innovative molecular-cooperative-interaction strategy is elaborately provided to realize honeycomb-like FTC electrodes.The nitrogen-doped porous carbon monolith(N-PCM)is obtained with advantages of interconnect pore structure and abundant nitrogen doping.Such strategy is based on naturally abundant molecular precursors,and free of pore-templates,expensive polymerization catalyst,and dangerous reaction solvent,rendering it a sustainable and cost-effective process.Systematic control experiments reveal that strong interactions among molecular precursors promise the structural stability of N-PCM during carbonization,and rational selection of molecular precursors with chemical blowing features is key step for well-developed honeycomb-like pore structure.Interestingly,the optimized sample exhibits hierarchical pore structure with specific surface area of 626.4 m^(2)g^(-1)and rational N-doping of 7.01 wt%.The derived SC electrode with high mass loading of 40.1 mg cm^(-2)shows an excellent areal capacitance of 3621 mF cm^(-2)at 1 mA cm^(-2)and good rate performance with 2920 mF cm^(-2)at 25 mA cm^(-2).Moreover,the constructed aqueous symmetric SC and quasi-solid-state SC produce high energy densities of 0.32 and 0.27 mWh cm^(-2),respectively.We believe that such a composition/microstructure controllable method can promote the fabrication and development of other thick electrodes for energy storage devices.

Self-swelling derived frameworks with rigidity and flexibility enabling high-reversible silicon anodes

Silicon is recognized as the most advantageous next-generation anode material for LIBs in terms of its extremely high theoretical capacity and appropriate operating voltage.However,the application of Si anode is limited by huge volume expansion emerging with cycling,which in turn induces the collapse of the electrode structure,resulting in rapid capacity decay.Here,we report a strategy using self-swelling artificial laponite to prepare a laponite/MXene/CNT composite framework with both rigidity and flexibility,which can excellently address these challenges of Si anode.The self-swelling artificial laponite participates in the construction of hierarchical and porous structures,providing sufficient buffer space to mitigate the volume expansion of the LixSi alloying reaction.Meanwhile,tough and tightly cross-linked silicate nanosheets can improve the mechanical strength of the framework for strong structural stability.More importantly,the negative charge between the layers of artificial laponite can effectively promote fast Li-ion transport in the electrode.This free-standing silicon anode enables the preparation of high areal capacity electrodes to further enhance the energy density of LIBs and a higher reversible capacity of 2381.8 mAh/g at 0.1 C after 50 cycles with an initial coulombic of 85.6%.This work provides a simple and practical fabrication strategy for developing high-performance Si-based batteries,which can speed up their commercialization.