燃油掺水对内燃机理想循环的影响

一、理想循环内燃机的理想循环如图1所示。A-B 为绝热压缩,B-C 为等容加热,C-D 为等压加热,D-E为绝热膨胀,E-A 为等容放热。该理想循环以下述假定为基础: 1.

Structure and electrochemical hydrogen storage characteristics of La_(0.8-x)Pr_xMg_(0.2)Ni_(3.15)Co_(0.2)Al_(0.1)Si_(0.05) (x=0-0.4) electrode alloys

For the purpose of improving the electrochemical cycle stability of the La-Mg-Ni based A2BT-type electrode alloys, both reducing Mg content and substituting La with Pr were adopted. The Lao.8-xPrxMg0.2Ni3.15Co0.2A10.1Si0.05 （x=0, 0.1, 0.2, 0.3, 0.4） electrode alloys were fabricated by casting and annealing. The investigation on the structures and electrochemical performances of the alloys was performed. The obtained results reveal that the as-cast and annealed alloys comprise two major phases, （La, Mg）2Ni7 phase with the hexagonal Ce2NiT-type structure and LaNi5 phase with the hexagonal CaCus-type structure, as well as a little residual LaNi3 phase. It is also found that the addition of Pr element observably affects the electrochemical hydrogen storage characteristics of the alloys, just as the discharge capacity and high rate discharge ability （HRD） first rise then fall with the growing of Pr content, and among all the alloys, the as-cast and annealed （x=0.3） alloys generate the largest discharge capacities of 360.8 and 386.5 mA.h/g, respectively. Additionally, the electrochemical cycle stability of all the alloys markedly grows with the increase of Pr content. The capacity retaining rate （S100） at the 100th charging and discharging cycle is enhanced from 64.98% to 77.55% for the as-cast alloy, and from 76.60% to 95.72% for the as-annealed alloy by rising Pr content from 0 to 0.4. Furthermore, the substitution of Pr for La results in first increase and then decrease in the hydrogen diffusion coefficient （D）, the limiting current density （IL） as well as the electrochemical impedance.

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.

High-capacity organic electrode material calix[4] quinone/CMK-3 nanocomposite for lithium batteries

Organic lithium-ion batteries（OLIBs） represent a new generation of power storage approach for their environmental benignity and high theoretical specific capacities.However, it has the disadvantage with regard to the dissolution of active materials in organic electrolyte. In this study, we encapsulated high capacity material calix[4]quinone（C4Q） in the nanochannels of ordered mesoporous carbon（OMC）CMK-3 with various mass ratios ranging from 1：3 to 3：1, and then systematically investigated their morphology and electrochemical properties. The nanocomposites characterizations confirmed that C4Q is almost entirely capsulated in the nanosized pores of the CMK-3 while the mass ratio is less than2：1. As cathodes in lithium-ion batteries, the C4Q/CMK-3（1：2） nanocomposite exhibits optimal initial discharge capacity of 427 mA h g^（-1） with 58.7% cycling retention after 100 cycles. Meanwhile, the rate performance is also optimized with a capacity of 170.4 mA h g^（-1） at 1 C. This method paves a new way to apply organic cathodes for lithium-ion batteries.

Oxygen vacancies-rich cobalt-doped NiMoO4 nanosheets for high energy density and stable aqueous Ni-Zn battery

The enhancement of energy density and cycling stability is in urgent need for the widespread applications of aqueous rechargeable Ni-Zn batteries.Herein,a facile strategy has been employed to construct hierarchical Co-doped NiMoO4nanosheets as the cathode for high-performance Ni-Zn battery.Benefiting from the merits of substantially improved electrical conductivity and increased concentration of oxygen vacancies,the NiMoO4with 15%cobalt doping(denoted as CNMO-15)displays the best capacity of 361.4 m A h g-1at a current density of 3 A g-1and excellent cycle stability.Moreover,the assembled CNMO-15//Zn battery delivers a satisfactory specific capacity of 270.9 mA h g-1at 2 A g-1and a remarkable energy density of 474.1 W h kg-1at 3.5 kW kg-1,together with a maximum power density of 10.3 kW kg-1achieved at 118.8 W h kg-1.Noticeably,there is no capacity decay with a 119.8%retention observed after 5000 cycles,demonstrating its outstanding long lifespan.This work might provide valuable inspirations for the fabrication of high-performance Ni-Zn batteries with superior energy density and impressive stability.

Oxygen vacancies boosting ultra-stability of mesoporous ZnO-CoO@N-doped carbon microspheres for asymmetric supercapacitors

Long-term cycling stability of pseudocapacitive materials is pursued for high-energy supercapacitors.Herein,the mesoporous zinc-cobalt oxide heterostructure@nitrogendoped carbon(ZnO-CoO@NC)microspheres with abundant oxygen vacancies are self-assembled through a hydrothermal method combined with an annealing post-treatment.The multifunctional polyvinyl pyrrolidone(PVP)is used as a structure-directing agent,the precursor of NC and the initiator of abundant oxygen vacancies in zinc-cobalt oxide microspheres.XPS demonstrates the generation of surface oxygen vacancies resulted from the reduction effect of conductive NC,and further confirms the weaker interaction between the metal ions and oxygen atoms.As a result,the electrode based on ZnO-CoO@NC in 2 mol L^-1 KOH shows enhanced capacitive performance with an excellent cycle stability of 92%retention of the initial capacitance after 40,000 charge-discharge cycles at 2 A g^-1,keeping the morphology unchanged.The assembled asymmetric supercapacitor,graphene//ZnO-CoO@NC,also performs good cyclic stability with 94%capacitance retention after 10,000 cycles at 2 A g^-1.The remarkable electrochemical performance of the self-assembled ZnO-CoO@NC composite is attributed to the mesoporous architecture,abundant oxygen vacancies,conductive ZnO scaffold for CoO crystals forming heterostructure of ZnO-CoO and the high conductive NC layer covering outside of the multi-metal oxide nanoparticles.Hence,the ZnO-CoO@NC holds great promise for high-performance energy storage applications.

Post-annealing tailored 3D cross-linked TiNb2O7 nanorod electrode: towards superior lithium storage for flexible lithium-ion capacitors

TiNb2O7 anode materials(TNO)have unique potential for applications in Li-ion capacitors(LICs)due to their high specific capacity of ca.280 mA h g^-1 over a wide anodic Li-insertion potential window.However,their highrate capability is limited by their poor electronic and ionic conductivity.In particular,studies on TNO for LICs are lacking and that for flexible LICs have not yet been reported.Herein,a unique TNO porous electrode with cross-linked nanorods tailored by post-annealing and its application in flexible LICs are reported.This binder-free TNO anode exhibits superior rate performance(~66.3%capacity retention as the rate increases from 1 to 40 C),which is ascribed to the greatly shortened ion-diffusion length in TNO nanorods,facile electrolyte penetration and fast electron transport along the continuous single-crystalline nanorod network.Furthermore,the TNO anode shows an excellent cycling stability up to 2000 cycles and good flexibility(no capacity loss after continuous bending for 500 times).Model flexible LIC assembled with the TNO anode and activated carbon cathode exhibits increased gravimetric and volumetric energy/power densities(~100.6 W h kg^-1/4108.8 W kg^-1;10.7 mW h cm^-3/419.3 mW cm^-3),more superior to previously reported hybrid supercapacitors.The device also efficiently powers an LED light upon 180°bending.