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Ni added Si-Al Alloys with Enhanced Li<sup>+</sup> Storage Performance for Lithium-Ion Batteries
Umirov, Nurzhan,Seo, Deok-Ho,Jung, Kyu-Nam,Kim, Hyang-Yeon,Kim, Sung-Soo The Korean Electrochemical Society 2019 Journal of electrochemical science and technology Vol.10 No.1
Here, we report on nanocrystalline Si-Al-M (M = Fe, Cu, Ni, Zr) alloys for use as an anode for lithium-ion batteries, which were fabricated via a melt-spinning method. Based on the XRD and TEM analyses, it was found that the Si-Al-M alloys consist of nanocrystalline Si grains surrounded by an amorphous matrix phase. Among the Si-Al-M alloys with different metal composition, Ni-incorporated Si-Al-M alloy electrode retained the high discharge capacity of 2492 mAh/g and exhibited improved cyclability. The superior $Li^+$ storage performance of Si-Al-M alloy with Ni component is mainly responsible for the incorporated Ni, which induces the formation of ductile and conductive inactive matrix with crystalline Al phase, in addition to the grain size reduction of active Si phase.
Umirov, Nurzhan,Yamada, Yuto,Munakata, Hirokazu,Kim, Sung-Soo,Kanamura, Kiyoshi Elsevier 2019 Journal of Electroanalytical Chemistry Vol.855 No.-
<P><B>Abstract</B></P> <P>Attractive electrochemical properties of Li<SUB>4</SUB>Ti<SUB>5</SUB>O<SUB>12</SUB> (LTO) as an anode material for lithium-ion batteries originate primarily from the lithium-ion diffusion behavior in the crystal lattice. Therefore, it is extremely important to understand the inherent material properties that are favorable for superior kinetic performance. Here we report on the intrinsic electrochemical properties of LTO without the influence of inactive electrode components (e.g., binder, conductive agent) using single-particle measurement technique. Electrochemical analysis revealed an exceptionally high rate capability of a single LTO particle compared to the conventional LTO-based electrode. In particular, a single LTO particle demonstrates capacity retention of 88% even at 440 C-rate, while conventional LTO-based electrode shows a two-fold decrease in capacity at 30 C-rate, though it is temperature dependent. Particular attention is paid to determine the correlation of phase transition behavior in a single LTO particle with activation energies of exchange current (<I>i</I> <SUB> <I>o</I> </SUB>), charge transfer resistance (<I>R</I> <SUB> <I>ct</I> </SUB>) at the electrode/electrolyte interface, and diffusivity (<I>D</I>) of lithium-ion in the lattice obtained by single-particle measurement technique.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The intrinsic properties of LTO were investigated by single particle measurement. </LI> <LI> Single LTO particle shows outstanding rate capability vs. composite LTO electrode. </LI> <LI> Activation energies of <I>i</I> <SUB> <I>o</I> </SUB>, <I>R</I> <SUB> <I>ct</I> </SUB>, and <I>D</I> evaluated in the range of −10 °C–80 °C. </LI> <LI> LTO reaction is single-phase rather than two-phase at certain temperatures. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Nurzhan Umirov,서덕호,김태근,김향연,김성수 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.71 No.-
This paper reports an electrochemically highly reversible Si–Ni alloy based electrode through themicrostructure and composition analysis using XRD and HR-TEM combined with EDS. Nano-Si( 200 nm) embedded in the inactive NiSi2/NiSi matrix synthesized using industrial-scale rapidsolidification process (RSP). In addition, comprehensive analysis of HR-TEM images, dQ/dV and OCV plotsprovides powerful insights into the cycle life degradation of Si-alloys caused by the material state changeupon cycling.
Efficient Use of Bluetooth in Networked Control Systems
Ulugbek Umirov,Jung-Il-Park 제어로봇시스템학회 2012 제어로봇시스템학회 국제학술대회 논문집 Vol.2012 No.10
In this paper the application of Bluetooth for networked control systems is discussed. The complexity of communication with Bluetooth core module via HCI is given. The Bluetooth profiles simplifying the process, particularly SPP and HID profiles, are discussed and pros and cons of each one are covered. While SPP profile is widely used by engineers because of its simplicity and seamless transition of old wired devices to wireless, a HID profile offers comparative simplicity, native support by operating systems and is designed for low-latency requiring devices, which is a typical requirement for control systems. A number of experiments on DC motor position control were performed and it is proved that HID profile based control outperforms SPP based control and has comparable performance with SCO link based control.
A porous Si-based alloy as the promissing anode material for high-performance Li-ion battery
( Nurzhan Umirov ),김성수,연지수 한국공업화학회 2018 한국공업화학회 연구논문 초록집 Vol.2018 No.0
A porous structured Si-based alloy comprising Ni, Al, Ti (Si-NAT alloy) was successfully prepared using the melt-spinning technique followed by acid treatment. The morphology and surface area of the porous Si-NAT alloy was evaluated by scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) method. As prepared porous Si-NAT alloy has 15 times larger surface area, compared to the rigid sample (untreated). Improved electronic conductivity of the Si-NAT alloy was enabled due to the formation of inactive matrix along with the porous structure, which buffer the stress repeatedly generated by the volume changes during the lithiation/delithiation process. The porous Si-NAT alloy shows stable cycle performance over 30 cycles without severe capacity degradation. A galvanostatic intermittent titration technique (GITT) and single-particle measurement provided the detailed insight into the internal properties of the porous Si-NAT alloy.
Bluetooth Synchronous Connection Oriented Link Usage in Networked Control Systems
Ulugbek Umirov,박정일(Jung-Il Park) 제어로봇시스템학회 2012 제어·로봇·시스템학회 논문지 Vol.18 No.8
In this paper the usage of Bluetooth in networked control systems is described. ACL links and commonly used serial port profile built on top of ACL links are analyzed and their problems such as unpredictable latency are discovered. SCO link packet scheduling, latency estimation and setup procedure are examined. SCO link is suggested as proper link for NCS, due to its low latency and low variance. Smith predictor use for latency compensation is described and its impact on control performance is estimated. A number of experiments on DC motor position control are performed and control performance of system utilizing SCO link with and without Smith predictor is proved to be higher than control performance of system utilizing ACL link.
Yarn Tension Control of Winding Machine Using Active Tensioner
Ulugbek R. Umirov(울루구벡),Seung Hyun Jung(정승현),Chang Wook Han(한창욱),Jung-Il Park(박정일) 제어로봇시스템학회 2008 제어·로봇·시스템학회 논문지 Vol.14 No.9
This paper is devoted to yarn tension control problem in winding machines. The passive take-up unit is replaced by active one with ADRC(Active Disturbance Rejection Control) and it was compared with the method using conventional PD(Proportional¬Derivative) controller. The main part of ADRC is ESO(Extended State Observer) which continuously estimates nonlinearities of the system, such as intrinsic nonlinearity, external disturbance and sensor noise. Then the estimated nonlinearity is used to compensate the real one, thus making controlled system linear. A number of experiments have been conducted in order to verify the performance of the original winding system to the modified one. Experiments have shown improved efficiency of the system with adopting active yarn tension control. Experimental results show that the ADRC achieves a better tension response than PD controller and is robust to parameters variation.
Applicability of ZigBee for Real-Time Networked Motor Control Systems
Ulugbek R. Umirov,Seong-Hyun Jeong,Jung-Il Park 제어로봇시스템학회 2008 제어로봇시스템학회 국제학술대회 논문집 Vol.2008 No.10
This paper discusses networked real-time control systems. The common network and ZigBee specific problems are discussed and methods to overcome them are explained. Limitations of ZigBee networks, sources of delay and benefits of broadcast mode over unicast mode for control loop time delay minimization are reviewed. It is explained how play-back buffer, originally used in multimedia play-back, can help to eliminate variance of loop time delay. To cope with achieved constant loop time delay the Smith predictor is used. Performance of control loop utilizing conventional PID controller, Smith predictor and play-back buffer is verified via experiments and proved to be efficient.