非导电工程瓷高能量电容单脉冲放电高效加工试验研究

针对传统加工方法在加工非电工程陶瓷时存在加工效低、本高以及加工表面质量差等缺点,本文提出了非电工程陶瓷高能量电容高效电火花加工新方法,并进行了单脉冲放电试验研究,结表明,该方法采用高电压大电容以及较高放电能量,能够较大地提高材料去除效,单次脉冲放电陶瓷去除量可达17.63mm3.对加工极性、峰值电压、电容、限流电阻、工具电极进给方式、工具电极截面积以及辅助电极厚度等参数对陶瓷蚀除坑体积、工具电极损耗以及辅助电极损耗等性能影响进行了试验研究与理论分析,了相应规关系.采用扫描电子显微镜对单脉冲放电坑微观形貌进行了观测.结表明:放电坑表面溅射状,陶瓷主要以剥落方式去除,放电通道中心区域部分材料以熔化蒸发方式去除,且材料去除效随着加工参数增大而增强.

Hydrothermal Synthesis and Electrochemical Properties of Amorphous LiMoS2 as a High Capacity Anode Material for Lithium Ion Batteries

The LiMoS： anode material for lithium ion rechargeable batteries were synthesized by a hydrothermal method at 150 ℃. According to our measurements with X-ray diffraction, LiMoS2 was amorphous structure. Electrochemical measurements results showed that LiMoS2 exhibited large lithium storage capacities.

High Voltage Pulse Power and the Technics for the Capacitor Power-Storage Type

Lower hybrid wave （LHW）, electro cyclotron （EC） and neutral beam injection （NBI） etc. are the important methods of auxiliary heating. They would be devoted to the HL-2A tokamak step by step. In order to satisfy the debug of each system and the need of the experiment, the system should be equipped with high voltage pulse power （HVPP） according to the requirement.

The way to improve the energy density of supercapacitors:Progress and perspective

Compared with other energy storage devices, supercapacitors have superior qualities,including a long cycling life,fast charge/discharge processes,and a high safety rating.The practical use of supercapacitor devices is hindered by their low energy density.Here,we briefly review the factors that influence the energy density of supercapacitors.Furthermore,possible pathways for enhancing the energy density via improving capacitance and working voltage are discussed. In particular,we offer our perspective on the most exciting developments regarding high-energy-density supercapacitors, with an emphasis on future trends.We conclude by discussing the various types of supercapacitors and highlight crucial tasks for achieving a high energy density.

Exploration and progress of high-energy supercapacitors and related electrode materials

As one of new electrical energy storage systems, supercapacitors possess higher energy density than conventional capacitors and larger power density than batteries, integrating substantial merits with high energy, large power delivery, long cycle life, obvious safety, and low cost. However, the unsatisfying energy density is the inhabiting issue for the wide commercial applications. As the energy density(E, W h kg?1) is directly proportional to specific capacitance(C, F g?1) and the square of operating voltage(V, V), in this review, we summarize the recent progress in two sections: the exploration of high-performance electrode materials to achieve high specific capacitance and the construction of high-voltage supercapacitor systems for high working voltage. The progressive explorations and developments in supercapacitors could guide the future research towards high-performance, low-cost, and safe energy storage devices.

TiO2 nanotube branched tree on a carbon nanofiber nanostructure as an anode for high energy and power lithium ion batteries

The inherently low electrical conductivity of TiO2-based electrodes as well as the high electrical resistance between an electrode and a current collector represents a major obstacle to their use as an anode for lithium ion batteries. In this study, we report on high-density TiO2 nanotubes （NTs） branched onto a carbon nanofiber （CNF） ＂tree＂ that provide a low resistance current path between the current collector and the TiO2 NTs. Compared to a TiO2 NT array grown directly on the current collector, the branched TiO2 NTs tree, coupled with the CNF electrode, exhibited -10 times higher areal energy density and excellent rate capability （discharge capacity of -150 mA.h.g-1 at a current density of 1,000 mA·g-1）. Based on the detailed experimental results and associated theoretical analysis, we demonstrate that the introduction of CNFs with direct electric contact with the current collector enables a significant increase in areal capacity （mA·h·cm-2） as well as excellent rate capability.

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.

Novel layered K0.7Mn0.7Ni0.3O2 cathode material with enlarged diffusion channels for high energy density sodium-ion batteries

As promising,low-cost alternatives of lithiumion batteries for large-scale electric energy storage,sodiumion batteries(SIBs)have been studied by many researchers.However,the relatively large size of Na+leads to sluggish diffusion kinetics and poor cycling stability in most cathode materials,restricting their further applications.In this work,we demonstrated a novel K+-intercalated Mn/Ni-based layered oxide material(K0.7Mn0.7Ni0.3O2,denoted as KMNO)with stabilized and enlarged diffusion channels for high energy density SIBs.A spontaneous ion exchange behavior in forming K0.1Na0.7Mn0.7Ni0.3O2between the KMNO electrode and the sodium ion electrolyte was clearly revealed by in situ X-ray diffraction and ex situ inductively coupled plasma analysis.The interlayer space varied from 6.90 to 5.76?,larger than that of Na0.7Mn0.7Ni0.3O2(5.63?).The enlarged ionic diffusion channels can effectively increase the ionic diffusion coefficient and simultaneously provide more K+storage sites in the product framework.As a proof-of-concept application,the SIBs with the as-prepared KMNO as a cathode display a high reversible discharge capacity(161.8 mA h g-1at0.1 A g-1),high energy density(459 W h kg-1)and superior rate capability of 71.1 mA h g-1at 5 A g-1.Our work demonstrates that the K+pre-intercalation strategy endows the layered metal oxides with excellent sodium storage performance,which provides new directions for the design of cathode materials for various batteries.