Virus‐Templated Nickel Phosphide Nanofoams as Additive‐Free,Thin‐Film Li‐Ion Microbattery Anodes

Transition metal phosphides are a new class of materials generating interest as alternative negative electrodes in lithium‐ion batteries. However, metal phosphide syntheses remain underdeveloped in terms of simultaneous control over phase composition and 3D nanostructure. Herein, M13 bacteriophage is employed as a biological scaffold to develop 3D nickel phosphide nanofoams with control over a range of phase compositions and structural elements. Virus‐templated Ni₅P₄ nanofoams are then integrated as thin‐film negative electrodes in lithium‐ion microbatteries, demonstrating a discharge capacity of 677 mAh g^–1 (677 mAh cm^–3) and an 80% capacity retention over more than 100 cycles. This strong electrochemical performance is attributed to the virus‐templated, nanostructured morphology, which remains electronically conductive throughout cycling, thereby sidestepping the need for conductive additives. When accounting for the mass of additional binder materials, virus‐templated Ni₅P₄ nanofoams demonstrate the highest practical capacity reported thus far for Ni₅P₄ electrodes. Looking forward, this synthesis method is generalizable and can enable precise control over the 3D nanostructure and phase composition in other metal phosphides, such as cobalt and copper.     

As-deposited LiCoO2 thin film cathodes prepared by rf magnetron sputtering

LiCoO₂ thin films were deposited using radio frequency (rf) magnetron sputtering system on stainless steel substrates. Different rf powers, up to 150 W, were applied during deposition. The as-deposited films exhibited (1 0 1) and (1 0 4) preferred orientation and the nanocrystalline film structure was enhanced with increasing rf power. The film crystallinity was examined using X-ray diffraction, Raman scattering spectroscopy and transmission electron microscopy. The compositions of the films were determined by inductively coupled plasma-mass spectroscopy. The average discharge capacity of as-deposited films is about 59 μAh/(cm² μm) for cut-off voltage range of 4.2 and 3.0 V. From the electrochemical cycling data, it is suggested that as-deposited LiCoO₂ films with a nanocrystalline structure and a favorable preferred orientation, e.g. (1 0 1) or (1 0 4) texture, can be used without post-annealing at high temperatures for solid-state thin film batteries.     

Optimization and temperature effects on sandwich betavoltaic microbattery

The design scheme of a sandwich-structure betavoltaic microbattery based on silicon using63Ni is presented in this paper.This structure differs from a monolayer energy conversion unit.The optimization of various physical parameters and the effects of temperature on the microbattery were studied through MCNP.For the proposed optimization design,P-type silicon was used as the substrate for the betavoltaic microbattery.Based on the proposed theory,a sandwich microbattery with a shallow junction was fabricated.The temperature dependence of the device was also measured.The open-circuit voltaic(Voc)temperature dependence of the optimized sandwich betavoltaic microbattery was linear.However,the Voc of the betavoltaic microbattery with a high-resistance substrate exponentially decreased over the range of room temperature in the experiment and simulation.In addition,the sandwich betavoltaic microbattery offered higher power than the monolayer betavoltaic one.The results of this paper provide a significant technical reference for optimizing the design and studying temperature effects on betavoltaics of the same type.     

X-ray photoelectron spectroscopy: A powerful tool for a better characterization of thin film materials

X-ray photoelectron spectroscopy (XPS) is one of the most powerful tools to characterize thin films materials. To illustrate the use of XPS, some examples will be given on materials used as positive electrode in microbatteries. Further analyses of the film to understand the redox process are quite difficult with conventional methods due to the amorphous nature of the cathode. Here surface methods like XPS are very useful. Two main kinds of information can be obtained from XPS analysis: the oxidation states, and the determination of atomic environments. Different kinds of positive electrode materials were studied, titanium and molybdenum oxysulfides (MO _y S _z , M=Ti, Mo) and lithium cobalt oxide (Li _x CoO_2+y ) and have been illustrated in the present work. In light of the binding energies obtained for the reference compounds, several types of environments and different formal oxidation states have been found for the transition elements. XPS is also very useful for folllowing the oxydo-reduction mechanisms occurring during the intercalation and the de-intercalation of lithium, corresponding respectively to the discharge and the charge of the battery. After strict identification of each species, the evolution of their binding energies could be followed very easily. The XPS analyses of oxysulfides thin films at different stages of their cycling process have shown apparently good efficiency of the oxygen-rich compositions. During the redox process, the results obtained have clearly shown the important contribution of the sulfur atoms beside the transition metal atom.     

In situ Raman microspectrometry investigation of electrochemical lithium intercalation into sputtered crystalline V2O5 thin films

We report here the first in situ Raman microspectrometry study of the electrochemical lithium insertion and de-insertion reaction into crystalline sputtered Li_xV₂O₅ thin films (0 ≤ x ≤ 0.94) in liquid electrolyte. We show that the orthorhombic Pmmn symmetry of the pristine material is kept upon lithium intercalation in the Li_xV₂O₅ film (0 ≤ x ≤  0.94). In fact, a subsequent and unexpected solid solution behaviour is evidenced, leading to the typical Raman fingerprint of the -LiV₂O₅ phase for the Li₀.₉₄V₂O₅ composition. After the charge, a complete recovery of the local structure is found, in good accord with the excellent electrochemical reversibility exhibited by these thin films. Such limited structural changes differ from that usually observed for the bulk material, which emphasizes the key role of the microstructure and morphology on the nature and magnitude of the structural rearrangements induced by the lithium insertion process.     

基于β辐射伏特效应的同位素微电池理论模型研究

随着微型机械电子系统(MEMS)的发展,微能源逐渐成为MEMS应用中的一个非常关键的问题.在同时考虑了同位素的选择及其衰变类型、粒子能谱、放射粒子能量损失率、半导体特性、载流子的产生与复合等因素的基础上,提出了一个基于β辐射伏特效应的同位素微电池的理论模型.可以用该模型计算出微电池的短路电流和开路电压.得到的模拟结果比引用文献结果稍高,还得到了表面掺杂浓度、结深以及放射粒子活度对电池输出参数的影响.     

A study on the electrochemical properties of an Mg−Ni based thin film electrode for a microbattery

In order to investigate the possibility of a microbattery using an Mg₂Ni type alloy, we have studied the electrochemical properties of the Mg_1−xNi_x (x=0.33, 0.15, 0.10) thin film electrode. The thin films were prepared by DC magnetron co-sputtering using Mg and Ni targets and had an amorphous structure. The discharge capacities of the Mg_1−xNi_x (x=0.33, 0.15, 0.10) films increased as the Mg content increased, that of the Mg_0.9Ni_0.1 electrode increased with repeated charge-discharge cycles reached the maximum value, 228 mAh/g, after 10 cycles. The surface morphology of the film was changed to a needle-type porous structure by cycling. This article is based on a presentation made in “The 2nd KIM-JIM Joint Symposium: Hydrogen Absorbing Materials”, held at Hanyang University, Seoul, Korea, October 27–28, 2000 under the auspices of The Korean Institute of Metals and Materials and The Japan Institute of Metals.     

High Voltage MOSFET Gate/Bulk Driver Controller for a Microbattery Switch Matrix in a 0.35 μ m Microwave SOI Technology

Integrated microbatteries are being currently developed to act as a “micropower” source in microsatellites. The current and voltage rating of the microbattery is fixed. Certain highly miniaturized systems require higher voltages and currents. A switching matrix is designed to achieve the same. The switching matrix is designed using High Voltage Metal Oxide Semiconductor (MOS) structures and bulk isolated H gate transistors. This paper presents a design approach to help attain any random grouping pattern between the microbatteries. In this case, the result is an ability to charge microbatteries in parallel and to discharge microbatteries in parallel or pairs of microbatteries in series. This is achieved by providing the appropriate gate/bulk voltages to the matrix. High Voltage MOS structures are developed which can take higher drain-to-source voltages in a 3.3 V process. The designs are built using Microwave Silicon-on-Insulator process. Vinesh Sukumar received the B.E. degree in Electronics and Instrumentation Engineering from Nagarjuna University, Bapatla, India in 2000. He received his M.S. degree in Electrical and Electronics Engineering in 2003 from University of Idaho, Moscow, ID. He is presently pursuing his Doctoral degree in Electrical Engineering at University of Idaho, Moscow, ID. His research interests include Radiation Hard Analog Design and Integrated Power Electronics.     

Influence of deposition temperature on ionic conductivity of perovskite (Li_(0.5)La_(0.5))TiO_3 solid state electrolyte thin film

1IntroductionWith the development of electronic devices,thin fil m microbatteries have received great attention be-cause they can be completelyintegrated with microcircuits,such as microdevices,microsensors,and very-large-scale integration(VLSI)[1-3].The thin fil m microbattery is a promising alternative micropowersource because of its high energy density and good cell performances,which was fabricated by depositingthin fil ms of the cell components,i.e.cathode,electrolyte,anode,and current c…     

连铸坯热酸蚀检验反应机理及过程优化

 热酸蚀法是连铸坯质量检验的一种常用方法,但目前使用效果不稳定,检验过程中容易出现过腐蚀或腐蚀不够的现象,其反应机理也存在争议。以高碳钢为例,探索一种热酸蚀检验反应机理的研究方法,旨在确定热酸蚀检验的具体反应机理,并对热酸蚀检验的过程优化提供理论指导。首先原位分析组织形貌在酸蚀过程中的变化规律,然后对酸蚀前后物相变化和酸蚀过程中不同物相对应的腐蚀行为观察分析,结合对酸蚀过程进行的数值模拟、极化曲线测量及电化学理论,共同分析热酸蚀过程的反应机理,并由此展开过程优化。结果表明,热酸蚀检验机理可以用不同物相间的微电池反应解释,即铸坯中的Fe₃C相可以与周围基体发生微电池反应,碳浓度高的偏析区域Fe₃C较多,微电池分布密度大,在热酸蚀过程中腐蚀速率较快,铸坯中腐蚀速率的差异导致不同区域腐蚀形貌的不同,最终显示出铸坯的低倍组织及缺陷情况。并根据反应机理得出酸蚀效果随酸蚀时间的增长存在拐点,且所研究钢种最佳反应时间为300 s,同时发现适当提高温度可以增大铸坯中不同区域在酸蚀过程中腐蚀速率的差异,有利于改善酸蚀效果。这对连铸坯质量优化及高品质钢质量稳定性的提升具有重要意义,同时所提出的研究方法对类似检验的过程优化也具有参考价值。