This paper designs a hydrogen concentration online monitoring system, mainly completes the construction of the software and hardware platform, select the I.MX6ULL embedded processor as the core hardware platform and embedded Linux system transplantation, root file system construction, hardware peripherals driver design, complete the human-computer interface based on QT application framework and save the collected data to the memory of the embedded motherboard and send to the cloud in real time through the network port.

半无桥Boost功率因数校正(PFC)变换器拓扑在新能源领域有着重要研究价值,为合理设计变换器控制电路,以实现变换器宽范围的动态特性,此处建立了半无桥Boost PFC变换器小信号模型,并据此推导出基于平均电流控制的双闭环控制系统中电压控制环和电流控制环的传递函数,提出了补偿网络的参数设计方案,确保了变换器的动态特性和稳态特性.在此基础上,设计了一台开关频率100 kHz、额定输出400 V/600 W的原理样机,验证了基于平均电流控制电路参数设计方案的可行性和理论分析的正确性.

研制了一套HZDJ-2型电机学及电力拖动综合实验台,该电机实验台为电机学和电力拖动控制系统两门课程提供实验教学复用的大功率机组实验教学平台,能够实现各类电机稳态运行和特性测定,以及各类传统电力拖动系统控制规律和静、动态性能测定等实验内容.电机实验台自主设计了大功率电机驱动电源、可组合的电机机组以及集成式可调交直流RLC负载箱,采用了一系列新技术和新方法,使得其在实验内容设计和实验规模方面,相较于国内同类实验设备处于领先地位.该电机实验台的设计与实现方法在电气工程专业本科教学改革中具有较好的借鉴和推广价值.

High-voltage lithium metal battery (LMB) with LiCoO2 (>4.5 V) as the cathode shows great prospect in achieving high energy density, yet its performance is far below expectation. Diluted high-concentration electrolytes (DHCE) are proven effective to improve the performance, however the inherently thermodynamic instability of highly fluorinated diluents and the constitutionally interfacial instability of monofluorinated diluents hinders the stable operation under high voltage. Herein, a unique additive, 1,3,5-trifluorobenzene (3FB) is rationally incorporated with fluorobenzene (FB)-based DHCE to boost thermodynamic and interfacial stabilities of the electrolyte compared with hydrofluoroethers-based DHCE and FB-DHCE, respectively. Particularly, the FB possesses high energy barrier to defluorination, leading to superior thermodynamic stability of developed DHCE. Furthermore, 3FB can be preferentially reduced into a LiF-rich solid electrolyte interphase (SEI) and partial low-fluorated aromatic hydrocarbons, while these 3FB derivatives are likely to be oxidized on cathode, forming robust cathode electrolyte interphase (CEI) and significantly mitigating side reactions under high-voltage conditions. As a result, the Li-Cu cell using optimized electrolyte is endowed with ultrahigh Coulombic efficiency (CE: 99.2%) and long-term cycle life (>300 cycles) even at 3 mA cm−2. A 4.5V Li-LCO cell exhibits outstanding cycling stability (600 cycles, 80 % capacity retention) and the Li-LCO pouch cell deliver high specific energy of more than 370 Wh kg−1 under the practical condition. This work provide direction for further development of advanced electrolytes for high-voltage LMBs.

High-energy density and ultra-long cycling lifespan are of great significance in pursuit of practical lithium-sulfur (Li-S) batteries, in which the construction of ultrathick, high-areal-capacity, and stable-cycling sulfur cathodes remains challenging. Here, a unique layered reinforced concrete structure (LRCS) is reported by integrating an ice-template method with incorporating carbon fibers in the thick electrodes for Li-S batteries. The LRCS enables aligned through-channel structure and intertwined conductive network, which lead to both fast kinetics of ions/electrons transport and strengthened electrode integrity to tolerate the volume change during cycling and the dimensional deformation under a high compaction density. Benefiting from the unique structure, the ultra-thick Se0.05S0.95 @ pPAN cathode (20.2 mg cm(-2)) delivers a high capacity of 10 mAh cm(-2) and excellent capacity retention of 80.8% over 140 cycles at a low electrolyte-to-sulfur ratio of 2 and a negative-to-positive capacity ratio of 2.7, corresponding to a calculated energy density of 390 Wh kg(-1). This investigation not only provides guidance for the design of thick sulfur electrodes but also paves the way for the development of practical Li-S batteries.

The in-situ polymerization is a promising technique for achieving industrial-scale production of solid-state lithium metal batteries (LMBs). However, initiators must be used in the most of previously reported polymerization method, which would give rise to some adverse effect on the battery. Herein, an initiator-free, simple, clean and efficient technique-high-energy electronic beam (e-beam) irradiation-is employed to in-situ prepare gel polymer electrolytes (GPEs) based on vinyl ethylene carbonate (VEC) and poly(ethyleneglycol) dimetha-crylate (PEGDMA). The obtained GPEs deliver satisfactory ionic conductivity (0.17 mS cm(-1) at 27 degrees C), high lithium-ion transference number (0.76 at 27 degrees C) and good electrochemical stability (5.4 V, vs Li/Li+). The LiFePO4/Li (LFP/Li) batteries based on the GPEs achieve excellent cycling stability (85% retention after 270 cycles) and rate performance. More impressively, high-energy e-beam can penetrate through aluminum-plastic film to induce polymerization, which directly leads to the transformation from the liquid-state pouch cell to the solid-state. The solid-state LFP/Li pouch cell exhibits excellent cycling performance with a capacity retention of 83% after 100 cycles at 60 degrees C. What is also noteworthy that the GPEs realizes good safety performance even at combustion test. Therefore, employing high-energy e-beam as an in-situ solidification technique not only opens a novel pathway to large-scale production of solid-state LMBs, but also could greatly advance the development of high-energy-density LMBs.

Lithium (Li) metal is an ultra-high specific capacity and low potential ''holy grail'' anode for developing high energy density rechargeable Li metal batteries (LMBs), but its practical application suffers from the low Coulombic efficiency (CE) and dendritic lithium growth due to its thermodynamic instability to organic solvents. Here, we report a new diluted high concentration electrolyte (DHCE) containing lithium bis(fluorosulfonyl)imide, triethyl phosphate and fluorobenzene cosolvent, which not only guarantees lithium metal anode (LMA) with an 98.4 % high average CE over 250 cycles but greatly improves Li||NMC622 cells property (70 % capacity retention after 200 cycles at C/3 current density). Therefore, this new electrolyte can provide more possibilities for developing high-energy-density LMBs.

Lithium metal battery (LMB) is regarded as a rising star for next generation high energy density batteries. However, there is still a great challenge to achieve stable cycling of high-voltage LMBs, especially under practical conditions. Herein, we report a fluorobenzene-based (FB-based) diluted highly concentrated carbonate electrolyte with significantly improved physical and electrochemical properties. Employing FB as the diluent not only reduces the viscosity, density and cost of highly concentrated electrolyte, but also contributes to the formation of layer-like solid electrolyte interphase with enriched LiF. The collective superiority enables outstanding cycling stability of lithium metal anode. Consequently, Li||LiNi0.6Co0.2Mn0.2O2 batteries with high areal capacity (3.6 mAh cm-2) based on such electrolyte show excellent cycling performance under a range of realistic conditions, including lean electrolyte (3 g Ah-1), low-temperature (-20 degrees C), and limited Li source (50 mu m). This work provides a facile but effective method to achieve a stable high-voltage LMBs and demonstrates its potential in practical application.

Highly concentrated electrolytes (HCEs) significantly improve the stability of lithium metal anodes, but applications are often impeded by their limitation of density, viscosity, and cost. Here, fluorobenzene (FB), an economical hydrocarbon with low density and low viscosity, is demonstrated as a bifunctional cosolvent to obtain a novel FB diluted highly concentrated electrolyte (FB‐DHCE). First, the addition of FB suppresses the decomposition of dimethoxyethane (DME) on the Li metal by strengthening the interactions of DME and FSI − around Li + . Second, FB efficiently elevates the content of LiF in the solid electrolyte interphase (SEI) based on its electrochemical reduction reaction. The unique solvation and interfacial chemistry of FB‐DHCE enable dendrite‐free deposition of lithium with high Coulombic efficiency (up to 99.3%) and prolong cycling life (over 500 cycles at 1 mA cm −2 ). The performance of FB‐DHCE is further demonstrated in full cells under practical conditions, including ambient to low temperature (–20 °C), high areal capacity (7.6 mAh cm −2 ), high current density (3 mA cm −2 ), limited excess Li (20 µm Li), and lean electrolyte (3 g Ah −1 ). Employing FB as a cosolvent not only opens a novel pathway to stabilize Li metal anodes, but also could greatly advance the development of Li metal batteries.

Lithium-sulfur (Li-S) battery, with their inherent advantages of high-energy density, low-cost, and ecofriendliness, shows promise as next-generation energy storage system. However, the practical Li-S batteries are far from achieving high-energy density and stable operation, because of the irreversible loss of active materials in both Li anode and S cathode. Herein, a modified diluted high concentration electrolyte (MDHCE) was designed for the practical Li-S batteries, which achieves a high energy density of 325 Wh kg(-1) and stable cycling. Such an electrolyte enables a hybrid interface with high stability and fast Li-ion transport, thus improving the reversibility of Li anode and ameliorative kinetics of S cathode. The practicability of the MDHCE is further demonstrated in a 0.4 Ah Li-S pouch cell, which presents no obvious capacity fading with a steady Coulombic efficiency of 99.6%. This work not only provides guidance for electrolyte design, but also shines new lights towards practical high energy density Li-S batteries.

Over-lithiated organosulfides, such as sulfurized polyacrylonitrile (SPAN), are promising candidates of lithium metal anode (LMA) protection since they could form robust solid electrolyte interphases (SEIs), which is the key toward stable lithium metal batteries. So far, the mechanism of over-lithiation and evolution of the electrode surface is poorly understood. Herein, several in situ techniques were employed to study the over-lithiation process in SPAN, including in situ Raman spectroscopy to reveal the chemical transformation and in situ electrochemical atomic force microscopy (EC-AFM) to visualize interfacial evolution. The results undoubtedly prove the breaking of the C-S bond and formation of the C-Li bond during the over-lithiation process. The nucleophilic C-Li could further trigger the decomposition of the electrolyte to form an inorganic-organic hybrid SEI on the surface of SPAN, which allows uniform Li deposition and significantly improves the cycle stability of LMAs, as supported by the in situ EC-AFM characterization as well as a series of full cell tests. New insights into the over-lithiation mechanism of SPAN should facilitate the design of organosulfides to construct stable lithium metal anodes.

在分析改革开放以来国家战略发展及人才需求特点的基础上,梳理华中科技大学电气与电子工程学院电气工程实验教学体系建设历程.立足学院学科建设特色,将学院实验教学体系发展总结为三个阶段,第一阶段探索实验教学体系环节建设,强调理论认知和工程意识的培养;第二阶段围绕实验教学体系组织建设,强调综合设计和创新能力培养;第三阶段正在发展中,立足学院"电气化+"战略,强调国际视野和基于专业的思维习惯、行为习惯、道德习惯的培养.

The design of solid polymer electrolytes (SPE) with high ionic conductivity and excellent mechanical properties is challenging because these two properties are often conflicting. To achieve both, a reaction-controlled strategy is proposed based on the nanophase separation of an ionic transport pathway and a supporting matrix to balance ionic mobility and mechanical properties. Specifically, an elastic epoxy polymer electrolyte (eEPE), synthesized via two-step polymerization, combines outstanding mechanical strength (toughness of 3.4 MJ m-3) and high ionic conductivity (3.5 × 10-4 S cm-1 at 25 °C). The nanostructured eEPE is both tough and flexible, therefore promotes uniform deposition of Li even under a high current density (2 mA cm-2 and 2 mAh cm-2). Importantly, eEPE composite films greatly improve the safety performance of the LiFePO4/Li pouch cells: safe operations are achieved under several abusive conditions. This work highlights an alternative route for high-safety solid-state lithium metal batteries of the next generation.

Developing low cost, yet high-voltage electrolyte is significant to improve the energy density and practicability of lithium metal batteries (LMBs). Low concentration electrolyte has significant merits in terms of cost and viscosity; however, their poor compatibility with high-voltage LMBs hinders its applications. Here, we develop a diluted low concentration electrolyte by replacing solvating cosolvent with a non-solvating cosolvent to facilitate the interaction between BF4 - and Li+, resulting in optimized interfacial chemistry and suppressed side reaction. Thus, the high-loading Li-LiCoO2 full cells (20.4 mg cm-2) deliver outstanding cycling stability and rate performance at a cutoff voltage of 4.6 V. More impressively, a Li-LiCoO2 pouch cell achieves an energy density of more than 400 Wh kg-1 under practical conditions with thin Li (50 μm) and lean electrolyte (2.7 g Ah-1). This work provides a rational approach to design a low concentration electrolyte, which can be extended to other high voltage battery systems.

Te as a eutectic accelerator can effectively enhance the kinetics of lithium–sulfur battery under solid-state conversion.

为了提高学生对该课程的重视程度,提高学习主动性,从而促进安全教育目标的达成,采用反向课程矩阵设计法进行课程设计.通过编制课程矩阵将安全教育各环节的教学目标、教学方法和评价指标呈现给学生,使学生能够在教师引导下进行主动学习.反向设计法的运用体现了“以学生学习为中心”“以学习效果为中心”的原则,所设计的“电类实验室安全教育”课程教学效果显著.

基于电子信息类学生对电的产生、传输和电能变换等知识缺乏了解,对电与磁两方面知识的掌握不平衡等问题,对工程科学学院低年级本科生开设了一门以电力电子应用系统为核心的项目训练课程.通过该课程的学习可以增加学生对发电-输变电-动力系统的感性认识,加强对各类电力电子应用系统的认识和理解,补充其对磁场及电磁转换方面知识的了解和应用.该课程的设计与实现方法在电子信息类专业本科教学改革中具有较好的借鉴和推广价值.

An ultrathick lithium metal anode (LMA) is a prerequisite for developing practical lithium-sulfur (Li-S) batteries that simultaneously meet the requirements of high areal capacity, lean electrolyte, and limited excess Li. Inspired by the electrochemical process for an organosulfur cathode, herein, we reconfigure such a sulfur cathode by using an overlithiation strategy to enable the formation of a high performance LMA. Specifically, an applicable ultrathick LMA is successfully constructed by overlithiating a well-known organosulfur cathode material, sulfurized polyacrylonitrile (SPAN). SPAN contains a polymeric pyridine structure with an outstanding lithium-ion affinity, so that it can act as a lithiophilic matrix. More importantly, a Li2S-rich solid electrolyte interphase (SEI) can be generated on the surface of SPAN during the overlithiation process. The synergistic effect of the lithiophilic matrix and a robust SEI leads to a dense deposition of lithium, which enables one to form an ultrathick LMA (159 μm, 30 mAh cm-2) with high Coulombic efficiency (99.7%). Such an LMA paired with a sulfur cathode of high areal capacity (up to 16 mAh cm-2) shows stable cycling under practical conditions of a lean electrolyte (2.2 μL mgS-1) and a negative-to-positive capacity (N/P) ratio as low as 1.3. The applicability of the ultrathick LMA was further verified with Li-S pouch cells, indicating a highly prospective route toward realization of practical Li-S batteries.

Practical applications of lithium metal anodes are gravely impeded by inhomogeneous lithium deposition, which results in dendrite growth. Electrolyte additives are proven to be effective in improving performance but usually serve only a single function. Herein, nitrofullerene is introduced as a bifunctional additive with a smoothing effect and forms a protective solid electrolyte interphase (SEI) layer on stable lithium metal anodes. By design, nitro-C 60 can gather on electrode protuberances via electrostatic interactions and then be reduced to NO 2 − and insoluble C 60 . Next, the C 60 anchors on the uneven groove of the lithium surface, resulting in a homogeneous distribution of Li ions. Finally, NO 2 – anions can react with metallic Li to build a compact and stable SEI with high ion transport. With a 5 mM nitro-C 60 additive, Li−Li symmetric cells show superior cycle stability in both carbonate and ether electrolytes, Li−sulfur batteries with a high cathode loading (10.6 mg cm − 2 , 6 mAh cm − 2 ) can achieve improved cycle retention of 63.2% over 100 cycles in a carbonate electrolyte, and full cells paired with a high-areal-capacity LiNi 0.6 Co 0.2 Mn 0.2 O 2 cathode (3.5 mAh cm − 2 ) exhibit a significantly enhanced cycle lifespan even under lean electrolyte conditions. This work not only develops a new insight into the application of fullerene but also provides a novel design strategy for electrolyte additives with multiple functions for stable lithium metal anodes. Reference: Jiang, Z.; Zeng, Z.; Yang, C.; Han, Z.; Hu, W.; Lu, J.; Xie, J. Nano Lett. 2019 , 19 , 8780−8786. Figure 1

The improved formula of time domain reflectometry (TDR) with variable coaxial cable length for electrical conductivity (EC) measurements was derived based on the theory of multi-section transmission line when the frequency was approaching zero. The derivation procedure was quite complicated. The goal of this study was to derive the formula when the multi-section transmission line was at zero frequency. At zero frequency, the multi-section transmission line became a direct-current circuit which consisted of the resistance of the soil sample, the series resistance and shunt conductance of the coaxial cable, and the characteristic impedence of the cable tester. Kirchhoff's voltage law was used to formulate the ratio of the voltage at the interface between the coaxial cable and the cable tester to the voltage of the cable tester. The formula for soil EC measurement derived from zero frequency was identical to that derived from the procedure when the frequency was approaching zero.