There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Solid-state electrolytes are attracting increasing interest for electrochemical energy storage technologies. In this Review, we provide a background overview and discuss the state of the art, ion-transport mechanisms and fundamental properties of solid-state electrolyte materials of interest for energy storage applications. We focus on recent advances in various classes of battery chemistries and systems that are enabled by solid electrolytes, including all-solid-state lithium-ion batteries and emerging solid-electrolyte lithium batteries that feature cathodes with liquid or gaseous active materials (for example, lithium–air, lithium–sulfur and lithium–bromine systems). A low-cost, safe, aqueous electrochemical energy storage concept with a ‘mediator-ion’ solid electrolyte is also discussed. Advanced battery systems based on solid electrolytes would revitalize the rechargeable battery field because of their safety, excellent stability, long cycle lives and low cost. However, great effort will be needed to implement solid-electrolyte batteries as viable energy storage systems. In this context, we discuss the main issues that must be addressed, such as achieving acceptable ionic conductivity, electrochemical stability and mechanical properties of the solid electrolytes, as well as a compatible electrolyte/electrode interface. This Review details recent advances in battery chemistries and systems enabled by solid electrolytes, including all-solid-state lithium-ion, lithium–air, lithium–sulfur and lithium–bromine batteries, as well as an aqueous battery concept with a mediator-ion solid electrolyte.

Lithium battery chemistries enabled by solid-state electrolytes

The science and technology of ultracapacitors are reviewed for a number of electrode materials, including carbon, mixed metal oxides, and conducting polymers. More work has been done using microporous carbons than with the other materials and most of the commercially available devices use carbon electrodes and an organic electrolytes. The energy density of these devices is 3¯5 Wh/kg with a power density of 300¯500 W/kg for high efficiency (90¯95%) charge/discharges. Projections of future developments using carbon indicate that energy densities of 10 Wh/kg or higher are likely with power densities of 1¯2 kW/kg. A key problem in the fabrication of these advanced devices is the bonding of the thin electrodes to a current collector such the contact resistance is less than 0.1 cm2. Special attention is given in the paper to comparing the power density characteristics of ultracapacitors and batteries. The comparisons should be made at the same charge/discharge efficiency.

Ultracapacitors: Why, How, and Where is the Technology

羟氨苄青霉素引起大疱性类天疱疮样疹

Note: Times Cited: 875 Reference EPFL-ARTICLE-206025doi:10.1021/cr0501846View record in Web of Science URL: ://WOS:000249839900009 Record created on 2015-03-03, modified on 2017-05-12

Complex Hydrides for Hydrogen Storage

With the development of the wireless communication and integrated circuits, Integrated passive devices (IPDs) have gained more and more application in radio frequency (RF) integrated circuit and monolithic microwave integrated circuits (MMICs). Among IPDs, MIM capacitor is a key passive component, widely used in DC-bias circuit, decoupling, etc. Therefore, the accuracy and practicability of the capacitance model is one of the key factors for the success of circuits design.However, since the MIM capacitor has many parasitic effects at high frequencies, it no longer exhibits pure capacitor characteristics anymore, thus, in high frequency circuit design, a simplified equivalent circuit model that can accurately characterizes the components is essential for the successful design of the circuit.As SiC-based GaN devices exhibit the advantages of high temperature and high power in millimeter wave applications, more and more integrated circuit use SiC-based GaN devices and components. With regards to this we produced a series of MIM capacitors of different sizes with air-bridges have been fabricated on 4H–SiC substrate. Also, we proposed a novel of simple broadband, based on the physical parameter equivalent circuit model of MIM capacitor structure.Based on the traditional equivalent circuit model, we introduce the corresponding components that characterize the skin effect and loss of the metal. The lumped element model is a simplified physical based model with broadband and high precision, and parameter extraction is given. To verify the accuracy and versatility of the model, we compared the measured and model simulated results of a series of MIM capacitors of different sizes. The results show that the model can accurately fit the S-parameters between measured and simulated in operating frequency range. In addition, the model shows good scalability as well.

A Novel Scalable Series MIM Capacitor Model for MMIC Applications


 GaN-High-electron-mobility transistors (GaN-HEMTs) were fabricated and investigated in detail to improve the linearity at high operation voltage. The scheme of dual-threshold coupling was adopted to mitigate the transconductance (Gm) non-linearity, and multi-finger drain field plate was employed to alleviate the high electric field. The proposed devices yielded Gm plateau of 5.5 V, 10 dB improvement in output third order intercept power. The load-pull measurements at 30 GHz delivered peak power-added-efficiency of 52.5 %, and saturation output-power-density of 5.5 W/mm, whose 2.4 dB improvement in gain compression, and 2 dB enhancement in 1-dB compression point, respectively.

Investigation of multi-fingers drain field plate in dual-threshold coupling AlGaN/GaN HEMTs for optimizing linearity at high electrical field in Ka-bands


 This paper studied the low-resistance ohmic contacts on InAlN/GaN with metal-organic chemical vapor deposition (MOCVD) regrowth technique. The 150 nm regrown n+-InGaN exhibits a low sheet resistance of 31Ω/□, resulting in an extremely low contact resistance of 0.102Ω·mm between n+-InGaN and InAlN/GaN channel. Mask-free regrowth process was also used to significantly improve the sheet resistance of InAlN/GaN with MOCVD regrown ohmic contacts. Then, the diffusion mechanism between n+-InGaN and InAlN during regrowth process was investigated with electrical and structural characterization, which could benefit the further process optimization.

Low-resistance ohmic contacts on InAlN/GaN heterostructures with MOCVD-regrown n+-InGaN and mask-free regrowth process

https://iopscience.iop.org/article/10.1088/1674-1056/abe117/pdf

Xiaohua Ma

Papers

A Novel Scalable Series MIM Capacitor Model for MMIC Applications

Investigation of multi-fingers drain field plate in dual-threshold coupling AlGaN/GaN HEMTs for optimizing linearity at high electrical field in Ka-bands

Low-resistance ohmic contacts on InAlN/GaN heterostructures with MOCVD-regrown n+-InGaN and mask-free regrowth process

Degradation of gate-recessed MOS-HEMTs and conventional HEMTs under DC electrical stress*

Physically Transient Threshold Switching Devices for Image Compression and Encryption Computing