Mobile Electronic Equipment Research Articles

Melt-Spinning Mesophase Pitch-Based Graphite Fibers as Anode Materials for High-Rate Lithium-Ion Batteries

Lithium-ion batteries have rapidly become the most widely used energy storage devices in mobile electronic equipment, electric vehicles, power grid energy storage devices and other applications. Due to their outstanding stability and high conductivity, carbon materials are among the most preferred anode materials for lithium-ion batteries. In this study, mesophase pitch-based graphite fibers (GFs) were successfully prepared through melt-spinning, thermo-oxidative stabilization, carbonization and graphitization and used as anode materials. The radial fiber structure can lower the activation energy and minimize the distance of the Li+ diffusion, while the highly conductive cross-linked network within the fibers benefits the speed up charge transmission. Thus, the as-synthesized graphite fibers demonstrate superior rate capability and cycle stability. GFs exhibit a capacity retention rate of 97.94% and reversible capacity of 327.8 mA h g−1 after 100 cycles at 0.1 C, which is higher than that of natural graphite anode materials (85.66% and 289.7 mA h g−1, respectively). Moreover, the as-synthesized graphite fibers deliver a capacity retention of 64.7% at a high rate of 5 C, which is considerably higher than that of natural graphite (19.7%).

Three-dimensional flexible molybdenum oxynitride thin film as a high capacity anode for Li-ion batteries

With the fast development of flexible wearable electronics, mobile electronic equipment, electric tool and electric vehicles, high specific capacity, superior cycle stability and excellent fast-charge performance are required for lithium-ion batteries (LIBs). Nevertheless, commercial graphite with the limited theoretical capacity (372 mAh g−1) and short lifespan is difficult to satisfy the requirements of the new generation of LIBs. In this work, the three-dimensional flexible molybdenum oxynitride (MNO) thin films with non-binder were prepared by magnetron sputtering approach. The charge transfer resistance and Li-ion diffusion coefficient were measured by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV), and the results show that molybdenum nitride is helpful to increase the diffusion and electron transfer of Li-ion. The MNO thin film annealed at 300 °C with irregular aggregate matrix structure shows a discharge capacity of 413 mAh g−1 after 180 cycles at 1 A g−1. The outstanding rate performance and cycle stability suggest that these binder-free thin film electrodes, especially nitrides, offer great opportunity for energy storage systems with fast-charge capabilities.

An effective modification strategy enhancing the structure stability and electrochemical performance of LiNi0.5Co0.2Mn0.3O2 cathode material for lithium-ion batteries

LiNixCoyMn1−x-yO2 (NCM) (x ≥ 0.5) have received more and more attention due to high energy density, which have been widely utilized in the fields of mobile electronic equipment and new energy vehicles. Nevertheless, these materials suffer severe capacity attenuation and inferior rate performance, hindering their commercialization. In this work, we design an effective strategy: co-modification of Nb doping and LiBO2 coating (NB-NCM) to stabilize the internal structure, reduce cation mixing, alleviate external side reactions and improve electrochemical performance. Material characterizations and electrochemical measurements were operated to comprehensively value the effect of co-modification on the structure, topography and electrochemical properties of NCM materials. As a result, Nb is doped into the bulk of the material and the surface of particle is uniformly coated with LiBO2. In addition, for the NB-NCM electrode, the discharge capacity retained 90.90% at 0.5 C rate after 50 cycles, which proves that co-modification is an effective method to stabilize structure and enhance electrochemical performance.

Systematic First-Principles Investigation of Mixed Transition Metal Olivine Phosphates LiM1-yM′yPO4 (M/M′ = Mn, Fe, and Co) as Cathode Materials

Li based batteries are widely used for powering mobile electronic equipment and are considered as highly promising power sources for electrical propulsion. Recent developments in the area of rechargeable lithium ion batteries for electronic devices and transportation have stimulated extensive studies of cathode materials which are the limiting factor in terms of voltage and energy density. In the current work we present a systematic computational study of the geometry, electronic structure, and electrochemical potential for olivines LixM1-yM′yPO4 (M/M′ = Mn, Fe, Co; x = 0.00, 1.00, x = y; y = 0.00, 0.25, 0.50, 0.75, and 1.00). We find that changes in cell volume as a function of transition metal composition may largely be ascribed to changes in the atomic volumes of the oxygen atoms, which modulate the electron charge distribution. Moreover, there is considerable charge transfer from lithium to the transition metal ions and oxygen atoms upon lithiation for all systems studied. The calculated cell potentia...

Heat Conduction in Mobile Electronic Equipment: Study on the Effects of Some Key Parameters on Heat Source Temperature Based on a Three-Layer Model

Heat conduction analysis is performed on a model system to survey the effects of geometric and thermal parameters on the temperature of an embedded heat source. A box model has the geometric characteristics of hand-held devices and has a laminar organization composed of a printed circuit board (PCB), air gap, and a system casing. Exploiting the laminar organization and thinness of the laminate an approximate solution is derived. The solution is used to produce a guide for thermal design analysts, which is concerned with the sensitivity of the heat source temperature to the effective thermal conductivity of the PCB. Numerical examples are shown for the models that have typical dimensions and material properties of actual equipment and PCB.

J012031 圧電マイクロフロアの性能特性の計測([J012-03]電子情報機器、電子デバイスの強度・信頼性評価と熱制御(3))

This study conducts a measurement of a performance of a piezoelectric micro blower. Mobile electronic equipment becomes smaller and thinner while their functions become more complex. As a result, a lot of components are mounted in an enclosure and flow passages for the cooling air become narrow. This causes significant pressure drop and general cooling fans cannot supply enough cooling air. We focused on a novel piezoelectric micro blower. In order to predict accurate cooling performance of the piezoelectric micro blower in thermal design, we tried to develop the measurement system of the performance characteristic curve of the blower. By using our system, we succeeded to measure the relationship between the supply flow rate and the static pressure rise of the micro blower.

Design and fabrication of an ultrahigh-luminance field-emission display

An ultrahigh-luminance field-emission display (FED) is designed in which a field emitter array (FEA) and memory function are integrated in every pixel of the display panel. The memory function consists of an emission-control thin-film transistor (TFT), a memory capacitor, a write-enable TFT, and a memory-discharging TFT. The operation mechanism is that the time of luminance of the pixel is made longer by the memory function; thus, luminance becomes higher. In principle, the maximum luminance of such a display is expected to be more than 100 000 cd/m2. The ultrahigh-luminance FED is applicable for daylight-readable displays used in mobile electronic equipment. The authors fabricated a prototype of the ultrahigh-luminance FED using Spindt-type FEA and poly-Si TFT technology. It was confirmed that the luminance of the display panel is controlled by the signal for the memory-discharging TFT, which means that the luminance can be dynamically controlled by the input signal. The maximum luminance of 1700 cd/m2 was achieved at a relatively low anode voltage of 1.5 kV. The higher luminance can be expected by applying higher anode voltage.

Development of a micro power-supply for a mobile electronic equipment

Development of a micro power-supply for a mobile electronic equipment

A Novel InSb Photodiode Infrared Sensor Operating at Room Temperature

ABSTRACTA microchip-sized InSb photodiode based infrared sensor (InSb PDS) that operates at room temperature was developed. The InSb PDS consists of 700 photodiodes connected in series and consumes no power, because it works in photovoltaic mode to output an open-circuit voltage. The InSb PDS has a typical responsivity of 1,900 V/W and an output noise of 0.15 μV/Hz1/2. A detectivity of 2.8×108 cmHz1/2/W was obtained at 300 K. The InSb PDS has performance high enough for applications such as mobile electronic equipment, personal computers, and consumer electronics

Electromagnetic noise superimposed on the electric power supply to electronic medical equipment.

The use of mobile medical electronic equipment driven at low electric power outputs has progressed rapidly in recent years. Voltage change and noise superimposed on the power supply could create obstacles to the operation of medical electronic equipment. We observed the quality of the power supply of medical electronic equipment in a university hospital, and found approximately 5% distortion on voltage. Possible causes of the distortion and factors involved in voltage/current distortion are discussed. Also shown are some points for avoiding power supply problems when using medical electronic equipment.

Optimization of the damper structure for electronic equipment

With the spread of mobile electronic equipment, such as notebook computers, mobile telephones and wireless remote controllers, requirements for the reliability of such equipment under severe environmental conditions such as high temperature. high humidity, water, pressure, vibration and impact have become high. One solution for these requirements is the packing of these electronic equipment in an environmental protection container. In this paper. we describe the development of an impact-load-protection container for mobile computers. To determine the optimum design parameters for each component of this container. we used the ROBUST design method. By using this impact protection container, the impact acceleration acting on the magnetic record disk in mobile computers was reduced to about I/3 the acceleration when no protection container is used.

Operation fulcrum and the fulcrum concept

GE Plastics’ vast design and materials knowledge about engineering thermoplastics has been helping shape the design and manufacture of handheld, portable, and mobile electronic products and equipment since their inception. Now, with the findings from Operation Fulcrum and the analysis of 15 commercially available notebooks, GE Plastics is helping the portable electronics community employ leading edge design solutions. Key findings of the program have been incorporated into an industry first: the Fulcrum Notebook Concept, which combines best-in-class thermal management and EMI shielding solutions and advances in engineering thermoplastics design for manufacturing and assembly. The Fulcrum Notebook Concept has been further enhanced by GE Plastics’ developments in thinwall technology and the creative solutions devised by the team at Polymer Solutions Inc. (PSI), a joint venture of GE Plastics and Fitch.

Mobile Electronic Recording System and Drill-off Data Illustrating Its Use

Abstract A mobile electronic system has been developed for recording drilling variables. Continuous records have been made, during field tests, of drilling rate, weight on bit, rotary rate, torque, fluid pressure and pump rate. Additionally, intermittent recordings have been made of strains and accelerations in various pieces of drilling-rig equipment, and longitudinal, torsional and bending stresses in the drill pipe. Transducers are placed on the rig for monitoring the variables. Cables connect the transducers through circuits to an oscillograph. The major electronic components of the equipment are housed in a trailer for protection and portability. The electronic recording system facilitates taking accurate drill-off data in the field. Data are presented on seven drill-offs taken in San Andres dolomite in Andrews County, Tex., at a depth of about 5,020 ft. In the test interval, drilling rate was proportional to weight on bit and to rotary rate raised to the 0.6 power. Introduction In the drilling research work conducted by Socony Mobil Oil Co., Inc., emphasis has been placed on a study of the factors affecting drilling rate, both with conventional and new drilling devices. The effects of several interrelated variables. have been studied. These include drilling rate, weight on bit, rotary rate, drill-string torque, drilling-fluid pressure and pump rate. In early field tests standard drilling-rig equipment was used in obtaining data. Because of the encouraging results obtained in these tests, an oscillographic recording system was fabricated. This mobile electronic recording equipment has been used successfully in the field and in the Socony Mobil Field Research Laboratory for four years. In addition to the mentioned variables, strains and accelerations in the drill string and in various rig components have been recorded and analyzed on several occasions. One such application occurred during Project Mohole, Phase I. Longitudinal, torsional and bending strains in the drill string were recorded while drilling in about 11,700 ft of water at the Guadalupe Island site. Several mechanical and electrical recording systems for drilling variables are now available for rental or purchase. These systems record from one to six variables. Accuracy, sensitivity, reliability and durability vary considerably on these units. The oscillographic system described in this paper was designed for improved accuracy and sensitivity. The subject recording equipment has many uses. One frequent application has been the obtaining of accurate drill-off data. In many instances the Lubinski calculation method for drill-off data is sufficiently accurate. However, in cases where severe buckling occurs during the drill-off or where the wall thickness of the drill pipe has changed due to wear or corrosion, this method can lead to considerable error. The technique described in this paper. utilizing the recording system, eliminates these inaccuracies. Description of the Recording System The mobile monitoring system is durable and versatile. It was designed for use in the field or in the laboratory. Signals from strain-gauge, potentiometric and tachometer-generator type transducers can be recorded. The frequency response and sensitivity of the circuits used for the various measurements can be varied over wide ranges. In fabricating the circuitry and components, simplicity was emphasized. This minimizes electronic problems resulting from transportation over rough terrain. Normally, signals are recorded without the use of amplifiers. During early field tests the apparatus was housed in a converted seismic-recording truck. The system was later installed in a house trailer. This instrument trailer is shown on the lower right in Fig. 1, together with the 1 1/2-ton truck used to transport the trailer. Hidden by the trailer is a portable 5-kw AC generator utilized for power. Fig. 2 is a block diagram of the transducers, recorder and control equipment. Each transducer is connected to the control circuitry by a shielded four-conductor cable. Fig. 3 shows the electronic equipment mounted in the trailer. The oscillograph recorder is located on the table at the left. The left relay rack contains an intercom system, control circuits for the transducers and a power supply. The right relay rack contains AC monitoring meters, a DC voltmeter, an oscilloscope and a voltage regulator. JPT P. 11^