活性炭纤维/NiO/MnO_2复合电极的结构及其电化学性能

利用溶胶凝胶法制备了活性炭纤维/NiO/MnO2新型复合电极材料。通过扫描电镜、X衍射和等温吸附方法测定复合电极的相态结构和比表面积,并采用循环伏安和恒流充放电实验测定其电化学性能。结果表明:金属氧化物是无定形非晶态结构,以微小颗粒分布在活性炭纤维表面;当Ni与Mn的物质的量比为3∶1,热处理温度为400℃,NiO/MnO2负载量为3.9%时,复合电极的比电容达到290.2 F/g,比活性炭纤维高1.3倍。

Influence of KOH activation techniques on pore structure and electrochemical property of carbon electrode materials

Taking the selection of coal-tar pitch as precursor and KOH as activated agent, the activated carbon electrode material was fabricated for supercapacitor.The surface area and the pore structure of activated carbon were analyzed by Nitro adsorption method. The electrochemical properties of the activated carbons were determined using two-electrode capacitors in 6 mol/L KOH aqueous electrolytes. The influences of activated temperature and mass ratio of KOH to C on the pore structure and electrochemical property of porous activated carbon were investigated in detail. The reasons for the changes of pore structure and electrochemical performance of activated carbon prepared under different conditions were also discussed theoretically. The results indicate that the maximum specific capacitance of 240 F/g can be obtained in alkaline medium, and the surface area, the pore structure and the specific capacitance of activated carbon depend on the treatment methods; the capacitance variation of activated carbon cannot be interpreted only by the change of surface area and pore structure, the lattice order and the electrolyte wetting effect of the activated carbon should also be taken into account.

To Improve the Accuracy of Laser Pulse Range Finding by Time Scale-Up

A method of improving the accuracy of laser pulse range finding from ±10 m to ±1 m inexpensively by means of time scale up is described. Time scale up can stretch the entire flight time by a factor of 1 000 and then the stretched result is counted to calculate the distance. The use of this technique decreases the resolution of counting from nanosecond to microsecond, therefore a separate counting oscillator followed by an interpolation operation is unnecessary. This technique can improve the accuracy of laser pulse range finding inexpensively and effectively.

Preparation and Electrochemical Performances of Nickel Metal Hydride Batteries with High Specific Volume Capacity

Cylindrical nickel metal hydride （Ni-MH） battery with high specific volume capacity was prepared by using the oxyhydroxide Ni（OH）2 and AB5 type hydrogen storage alloy and adjusting the designing parameters of positive and negative electrodes. The oxyhydroxide Ni（OH）2 was synthesized by oxidizing spherical β-Ni（OH）2 with chemical method. The X-ray diffraction （XRD） patterns and the Fourier transform infrared （PT-IR） spectra indicated that 7-NiOOH was formed on the oxyhydroxide Ni（OH）2 powders, and some H2O molecules were inserted into their crystal lattice spacing. The battery capacity could not be improved when the oxyhydroxide Ni（OH）2 sample was directly used as the positive active materials. However, based on the conductance and residual capacity of the oxyhydroxide Ni（OH）2 powders, AA size Ni-MH battery with 2560 mA.h capacity and 407 W·h·L^-1 specific volume energy at 0.2C was obtained by using the commercial spherical β-Ni（OH）2 and AB5-type hydrogen-storage alloy powders as the active materials when 10% mass amount of the oxyhydroxide Ni（OH）2 with 2.50 valence was added to the positive active materials and subsequently the battery designing parameters were adjusted as well. The as-prepared battery showed 70% initial capacity after 80 cycles at 0.5C. The possibility for adjusting the capacity ratio of positive and negative electrodes from 1 ： 1.35 to 1 ： 1.22 was demonstrated preliminarily. It is considered the as-prepared battery can meet the requirement of some special portable electrical instruments.

Liquid-phase preparation and electrochemical property of LiFePO_4/C nanowires

Olivine LiFePO4/C nanowires have been successfully synthesized by a simple and eco-friendly solution preparation.The phase,structure,morphology and composition of the as-prepared products were characterized by powder X-ray diffraction(XRD),scanning electron microscopy(SEM),thermogravimetric and differential-thermogravimetric analysis(TG-DTA) and energy dispersive X-ray spectrometry(EDS) techniques,showing uniform nanowire shape of LiFePO4/C with a diameter of 80-150 nm and a length of several microns.The heat-treated LiFePO4/C nanowires show excellent electrochemical properties of specific discharge capacity,rate capacity and cycling stability.In particular,the LiFePO4/C nanowires heat-treated at 400 °C show preferable first discharge specific capacity of 161 mA·h/g at 0.1C rate,while the voltage platform is 3.4 V and the first discharge specific capacity is 93 mA·h/g at 20C rate.The specific capacity retention is 98% after 50 cycles at 5C rate.

Experimental study on heat generation and dissipation performance of PEV Lithium-ion battery

Based on the lithium-ion battery pure electric vehicle （PEV） application, two capacity types of batteries are applied in thermal characteristic experiments. With the experimental comparison method, battery thermal characteristics and heat generation mechanism are studied. Experiments of batteries in cases of different dimensions, batteries with different air cooling velocity and two capacity types of batteries in free convection environment are put forward. Battery heat generation performance, heat dissipation performance and comparison of different capacity types＇ batteries are researched and summarized. Conclusions of battery heat generation and dissipation in PEV applications, important battery thermal management factors and suggestions are put forward.

A review of carbon-based hybrid materials for supercapacitors

Supercapacitors are gaining popularity due to their high cycling stability,power density,and fast charge and discharge rates.Researchers are ex-ploring electrode materials,electrolytes,and separat-ors for cost-effective energy storage systems.Ad-vances in materials science have led to the develop-ment of hybrid nanomaterials,such as combining fil-amentous carbon forms with inorganic nanoparticles,to create new charge and energy transfer processes.Notable materials for electrochemical energy-stor-age applications include MXenes,2D transition met-al carbides,and nitrides,carbon black,carbon aerogels,activated carbon,carbon nanotubes,conducting polymers,carbon fibers,and nanofibers,and graphene,because of their thermal,electrical,and mechanical properties.Carbon materials mixed with conducting polymers,ceramics,metal oxides,transition metal oxides,metal hydroxides,transition metal sulfides,trans-ition metal dichalcogenide,metal sulfides,carbides,nitrides,and biomass materials have received widespread attention due to their remarkable performance,eco-friendliness,cost-effectiveness,and renewability.This article explores the development of carbon-based hybrid materials for future supercapacitors,including electric double-layer capacitors,pseudocapacitors,and hy-brid supercapacitors.It investigates the difficulties that influence structural design,manufacturing(electrospinning,hydro-thermal/solvothermal,template-assisted synthesis,electrodeposition,electrospray,3D printing)techniques and the latest car-bon-based hybrid materials research offer practical solutions for producing high-performance,next-generation supercapacitors.

Porous spherical NiO@NiMoO4@PPy nanoarchitectures as advanced electrochemical pseudocapacitor materials

In this work, a rational design and construction of porous spherical Ni O@NiMoO4 wrapped with PPy was reported for the application of high-performance supercapacitor(SC). The results show that the NiMoO4 modification changes the morphology of Ni O, and the hollow internal morphology combined with porous outer shell of Ni O@NiMoO4 and Ni O@NiMoO4@PPy hybrids shows an increased specific surface area(SSA), and then promotes the transfer of ions and electrons. The shell of NiMoO4 and PPy with high electronic conductivity decreases the charge-transfer reaction resistance of Ni O, and then improves the electrochemical kinetics of Ni O. At 20 Ag^-1, the initial capacitances of Ni O, NiMoO4, Ni O@NiMoO4 and Ni O@NiMoO4@PPy are 456.0, 803.2, 764.4 and 941.6 Fg^-1, respectively. After 10,000 cycles, the corresponding capacitances are 346.8, 510.8, 641.2 and 904.8 Fg^-1, respectively. Especially, the initial capacitance of Ni O@NiMoO4@PPy is 850.2 Fg^-1, and remains 655.2 Fg^-1 with a high retention of 77.1% at30 Ag^-1 even after 30,000 cycles. The calculation result based on density function theory shows that the much stronger Mo-O bonds are crucial for stabilizing the Ni O@NiMoO4 composite, resulting in a good cycling stability of these materials.

Edge-enriched MoS@C/rGO film as self-standing anodes for high-capacity and long-life lithium-ion batteries

Restraining the aggregation and polysulfide dissolution of edge-enriched metal sulfides is of significance for their applications as anode materials of lithium-ion batteries(LIBs)with high capacity and long cycle-life.In this work,we have reported the incorporation of MoS2 nanocrystals into amorphous carbon on the surface of reduced graphene oxide(rGO)by balancing the decomposition rates of phenolic resin(PF)-impregnated ammonium thiomolybdate(ATM),which subsequently forms the MoS2@C/rGO film through redispersion and vacuum filtration.Such structural design effectively avoids the aggregation of MoS2 nanocrystals and Li2S loss,and meanwhile ion enrichment in amorphous carbon and diffusion reinforcement can greatly accelerate the electrochemical reaction kinetics.When applied as the selfstanding anode,the MoS2@C/rGO film possesses high reversible capacities of 1164 mA h g^-1 at the current density of 0.2 A g^-1 and 810 mA h g^-1 at 6.4 A g^-1.It also exhibits quite a high capacity retention after 1000 cycles at 3.2 A g^-1.This work develops the formation theory of incorporation structures and promotes their applications in energy storage devices.

Boosting reaction kinetics and reversibility in Mott-Schottky VS/MoS heterojunctions for enhanced lithium storage

Heterostructures have lately been recognized as a viable implement to achieve high-energy Li-ion batteries(LIBs) because the as-formed built-in electric field can greatly accelerate the charge transfer kinetics. Herein, we have constructed the Mott-Schottky heterostructured VS2/MoS2 hybrids with tailorable 1T/2H phase based on their matchable formation energy, which are made of metallic and few-layered VS2 vertically grown on MoS2 surface. The density functional theory(DFT) calculations unveil that such heterojunctions drive the rearrangement of energy band with a facilitated reaction kinetics and enhance the Li adsorption energy more than twice compared to the MoS2 surface. Furthermore, the VS2 catalytically expedites the Li–S bond fracture and meantime the enriched Mo6+ enables the sulfur anchoring toward the oriented reaction with Li+to form Li2S, synergistically enhancing the reversibility of electrochemical redox. Consequently, the as-obtained VS2/MoS2 hybrids deliver a very large specific capacity of 1273 m Ah g^-1 at 0.1 A g^-1 with 61% retention even at 5 A g^-1. It can also stabilize 100 cycles at 0.5 A g^-1 and 500 cycles at 1 A g^-1. The findings provide in-depth insights into engineering heterojunctions towards the enhancement of reaction kinetics and reversibility for LIBs.

Bowl-shaped NiCo2O4 nanosheet clusters as electrode materials for high-performance asymmetric supercapacitors

The development of transition metal oxidebased electrode materials with proper controlled structures is highly desirable for high-performance supercapacitors.However,it remains a major challenge.Here,we present the first synthesis of bowl-like Ni Co2O4nanosheet clusters through a simple soft template guided hydrothermal strategy.The resulting bowl-like clusters consist of numerous Ni Co2O4nanosheets with an average thickness of 19 nm and possess a mean diameter of 1μm along with a specific surface area of40 m2g^-1.Remarkably,serving as an electrode material in a three-electrode system,the bowl-like Ni Co2O4nanosheet clusters exhibit a high specific capacity of 1068 F g^-1at a current density of 1 A g^-1and excellent cycling stability with90%capacitance retention after 5000 charge-discharge cycles.Meanwhile,an asymmetric supercapacitor(ASC)assembled with the Ni Co2O4clusters and activated carbon(AC)as the two electrodes exhibits a high specific capacitance of 129 F g^-1at 1 A g^-1,along with a high energy density of 33 W h kg^-1at a power density of 0.66 k W kg^-1.Such performance is superior to those of many commercial supercapacitors.This study opens a new avenue for the construction of ordered complex particles with controlled architectures for energy storage and conversion applications.

Plum pudding model inspired KVPO4F@3DC as high-voltage and hyperstable cathode for potassium ion batteries

The investigation on the cathode material of potassium ion batteries(PIBs),one of the most promising alternatives to lithium ion batteries,is of great significance.Potassium vanadium fluorophosphate(KVPO4F)with a high working voltage is an appealing cathode candidate for PIBs,while the poor cycling performance and low electronic conductivity dramatically hinder the application.Herein,a plum pudding model inspired three-dimensional amorphous carbon network modified KVPO4F composite(KVPO4F@3DC)is successfully designed in this study to tackle these problems.In the composite,KVPO4F particles are homogeneously wrapped by a layer of amorphous carbon and bridged by crosslinked large area carbon sheets.As the cathode for PIBs,the KVPO4F@3DC composite exhibits a high average operating voltage about 4.10 V with a super-high discharge capacity of 102.96 mAh g^-1 at 20 mA g^-1.An excellent long cycle stability with a capacity retention of 85.4%over 550 cycles at 500 mA g^-1 is achieved.In addition,it maintains 83.6%of its initial capacity at 50 mA g^-1 after 100 cycles at 55℃.The design of KVPO4F@3DC with plum pudding structure provides facilitative electron conductive network and stable electrode/electrode interface for electrode,successfully innovating an ultra-stable and high-performance cathode material for potassium ion batteries.

Activated pyrolysed bacterial cellulose as electrodes for supercapacitors

In this paper, the bacterial celluloses(BCs) were pyrolysed in nitrogen and then activated by KOH to form a porous three- dimension-network electrode material for supercapacitor applications. Activated pyrolysed bacterial cellulose(APBC) samples with enlarged specific surface area and enhanced specific capacitances were obtained. In order to optimize electrochemical properties, APBC samples with different alkali-to-carbon ratios of 1, 2 and 3 were tested in two electrodes symmetrical capacitors. The optimized APBC sample holds the highest specific capacitance of 241.8 F/g, and the energy density of which is 5 times higher than that of PBC even at a current density of 5 A/g. This work presents a successful practice of preparing electrode material from environment-friendly biomass, bacterial cellulose.

Nitrogen-doped black titania for high performance supercapacitors

For energy storage system,it is still a huge challenge to achieve high energy density and high power density simultaneously.One potential solution is to fabricate electrochemical capacitors(ECs),which store electric energy through surface ion adsorption or redox reactions.Here we report a new electrode material,heavy nitrogen-doped(9.29 at.%)black titania(TiO2-x:N).This unique hybrid material,consisting of conductive amorphous shells supported on nanocrystalline cores,has rapid N-mediated redox reaction(TiO2-xNy+zH++ze■-TiO2-xNyHz),especially in acidic solutions,providing a specific capacitance of 750 Fg-1at 2 m V s-1(707 Fg-1at 1 A g-1),great rate capability(503 F g-1at 20 Ag-1),and maintain stable after initial fading.Being a new developed supercapacitor material,nitrogen-doped black titania may revive the oxide-based supercapacitors.

NiCoSe2/Ni3Se2 lamella arrays grown on N-doped graphene nanotubes with ultrahigh-rate capability and long-term cycling for asymmetric supercapacitor

In this paper, we report a one-step electrodeposited synthesis strategy for directly growing NiCoSe2/Ni3Se2 lamella arrays(LAs) on N-doped graphene nanotubes(N-GNTs) as advanced free-standing positive electrode for asymmetric supercapacitors. Benefiting from the synergetic contribution between the distinctive electroactive materials and the skeletons, the as-constructed N-GNTs@NiCoSe2/Ni3-Se2LAs present a specific capacitance of ~1308 F g^-1 at a current density of 1 A g^-1. More importantly, the hybrid electrode also reveals excellent rate capability(~1000 F g^-1 even at 100 A g^-1) and appealing cycling performance(~103.2% of capacitance retention over 10,000 cycles). Furthermore, an asymmetric supercapacitor is fabricated by using the obtained N-GNTs@NiCoSe2/Ni3Se2LAs and active carbon(AC) as the positive and negative electrodes respectively,which holds a high energy density of 42.8 W h kg^-1 at 2.6 k W kg^-1, and superior cycling stability of ~94.4% retention over 10,000 cycles. Accordingly, our fabrication technique and new insight herein can both widen design strategy of multicomponent composite electrode materials and promote the practical applications of the latest emerging transition metal selenides in next-generation high-performance supercapacitors.

Carbon electrodes with ionophobic characteristics in organic electrolyte for high-performance electric double-layer capacitors

Activated carbon(AC)in organic electrolytebased electric double-layer capacitors(EDLCs)usually suffers from low specific capacitance.Most studies on AC focus on improving its surface area and optimizing pore structures to enhance its electrochemical performance in EDLCs.Unfortunately,the interfacial microenvironment,which is composed of nanoporous carbon and the organic electrolyte confined in it,is always ignored.Herein,a simple and powerful strategy to create AC with an ionophobic surface is proposed to address the poor efficiency of the electric doublelayer process.The polar C±F bonds formed in the AC material are characterized through near-edge X-ray absorption fine structure and X-ray photoelectron spectroscopy.The ionophobic characteristic of YP-F60 s in an organic electrolyte is extensively studied via contact angle measurements and smallangle X-ray scattering spectroscopy.An EDLC constructed with YP-F60 s as the electrode and 1 mol L^(-1) tetraethylammonium tetrafluoroborate/propylene carbonate as the electrolyte demonstrates high specific capacitance,low internal resistance,and excellent cycling stability.Our results successfully demonstrate the importance of the interfacial microenvironment of AC and its confined electrolyte to the electrochemical performance of EDLCs.Our work also offers new perspectives on the use of the CF;plasma technique to fabricate low-cost superior carbon for EDLCs.

Tailoring electrolyte enables high-voltage Ni-rich NCM cathode against aggressive cathode chemistries for Li-ion batteries

The LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(Ni-rich NCM)cathode materials suffer from electrochemical performance degradation upon cycling due to detrimental cathode interface reactions and irreversible surface phase transition when operating at a high voltage(≥4.5 V).Herein,a traditional carbonate electrolyte with lithium difluoro(oxalato)borate(Li DFOB)and tris(trimethylsilyl)phosphate(TMSP)as dual additives that can preferentially oxidize and decompose to form a stable F,B and Si-rich cathode-electrolyte interphase(CEI)that effectively inhibits continual electrolyte decomposition,transition metal dissolves,surface phase transition and gas generation.In addition,TMSP also removes trace H_(2)O/HF in the electrolyte to increase the electrolyte stability.Owing to the synergistic effect of Li DFOB and TMSP,the Li/LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2) half cells exhibit the capacity retention 76.3%after 500 cycles at a super high voltage of 4.7 V,the graphite/LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)full cells exhibit high capacity retention of 82.8%after 500 cycles at 4.5 V,and Li/LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)pouch cells exhibit high capacity retention 94%after 200 cycles at 4.5 V.This work is expected to provide an effective electrolyte optimizing strategy compatible with high energy density lithium-ion battery manufacturing systems.

Calix[6]quinone as high-performance cathode for lithium-ion battery

Organic quinone compounds have attracted wide attention due to their high theoretical capacities.Here,a novel cyclic macromolecular calix[6]quinone(C6Q),which possesses 6 p-quinone units and can provide 12 electrochemical active sites,has been applied as a promising cathode material in lithium ion batteries(LIBs).The as-fabricated LIBs exhibited an initial specific capacity as high as 423 mA h g^-1(Ctheo=447 mA h g^-1)at 0.1 C.After 100 cycles,the capacity of C6Q maintained at 216 mA h g^-1,and even after 300 cycles,C6Q still achieved a high specific capacity of 195 mA h g^-1 with negligible capacity fading(as compared with the 100th cycle).Due to the large capacity and wide electrochemical window,C6Q can deliver a specific energy up to 1201 W h kg^-1.In addition,the method of immobilizing C6Q with ordered mesoporous carbon(OMC)CMK-3 could further enhance the electrochemical performance of C6Q.

Carbon-coating-increased working voltage and energy density towards an advanced Na3V2(PO4)2F3@C cathode in sodium-ion batteries

One main challenge for phosphate cathodes in sodium-ion batteries(SIBs)is to increase the working voltage and energy density to promote its practicability.Herein,an advanced Na3V2(PO4)2F3@C cathode is prepared successfully for sodium-ion full cells.It is revealed that,carbon coating can not only enhance the electronic conductivity and electrode kinetics of Na3V2(PO4)2F3@C and inhibit the growth of particles(i.e.,shorten the Na^+-migration path),but also unexpectedly for the first time adjust the dis-/charging plateaux at different voltage ranges to increase the mean voltage(from 3.59 to 3.71 V)and energy density from 336.0 to 428.5 Wh kg^-1 of phosphate cathode material.As a result,when used as cathode for SIBs,the prepared Na3V2(PO4)2F3@C delivers much improved electrochemical properties in terms of larger specifc capacity(115.9 vs.93.5 mAh g^-1),more outstanding high-rate capability(e.g.,87.3 vs.60.5 mAh g^-1 at 10 C),higher energy density,and better cycling performance,compared to pristine Na3V2(PO4)2F3.Reasons for the enhanced electrochemical properties include ionicity enhancement of lattice induced by carbon coating,improved electrode kinetics and electronic conductivity,and high stability of lattice,which is elucidated clearly through the contrastive characterization and electrochemical studies.Moreover,excellent energy-storage performance in sodium-ion full cells further demonstrate the extremely high possibility of Na3V2(PO4)2F3@C cathode for practical applications.

Carbon-coated Fe2O3 hollow sea urchin nanostructures as high-performance anode materials for lithium-ion battery

Fe2O3 has become a promising anode material in lithium-ion batteries (LIBs) in light of its low cost, high theoretical capacity (1007 mA h g^−1) and abundant reserves on the earth. Nevertheless, the practical application of Fe2O3 as the anode material in LIBs is greatly hindered by several severe issues, such as drastic capacity falloff, short cyclic life and huge volume change during the charge/discharge process. To tackle these limitations, carbon-coated Fe2O3 (Fe2O3@MOFC) composites with a hollow sea urchin nanostructure were prepared by an effective and controllable morphology-inherited strategy. Metal-organic framework (MOF)-coated FeOOH (FeOOH@-MIL-100(Fe)) was applied as the precursor and self-sacrificial template. During annealing, the outer MOF layer protected the structure of inner Fe2O3 from collapsing and converted to a carbon coating layer in situ. When applied as anode materials in LIBs, Fe2O3@MOFC composites showed an initial discharge capacity of 1366.9 mA h g^−1 and a capacity preservation of 1551.3 mA h g^−1 after 200 cycles at a current density of 0.1 A g^−1. When increasing the current density to 1 A g^−1, a reversible and high capacity of 1208.6 mA h g^−1 was obtained. The enhanced electrochemical performance was attributed to the MOF-derived carbon coating layers and the unique hollow sea urchin nanostructures. They mitigated the effects of volume expansion, increased the lithium-ion mobility of electrode, and stabilized the as-formed solid electrolyte interphase films.