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

Nitrogen atoms were introduced into a Pt/HfO2/TiN resistance random-access memory (RRAM) device to improve the resistive switching characteristics induced by a high-pressure nitridation treatment. Compared with a similar untreated HfO2 device, it exhibited superior performance, including a lower forming voltage, a higher on/off ratio, and high-endurance cycle operations. Current–voltage curve-fitting results confirmed the difference of the carrier transport mechanisms after the nitridation treatment. Finally, a reaction model was proposed to explain the improvement of RRAM switching due to the introduction of nitrogen atoms.

http://iopscience.iop.org/article/10.7567/APEX.11.084101/pdf

Performance improvement after nitridation treatment in HfO2-based resistance random-access memory

The invention discloses an InGaN solar cell with a p-i-n sandwich structure, mainly solving the problem of low conversion efficiency of the traditional InGaN solar cell. The solar cell comprises a substrate, an AlN nucleating layer (11) growing at high temperature, an unintentionally-doped GaN buffer layer (12), an n-GaN layer (13), an i-InGaN layer (14) and a p-GaN layer (15) in sequence from bottom to top, wherein the thickness of the n-GaN layer (13) is 50-100nm, and the electron concentration of the n-GaN layer (13) is 1*10 -6*10 /cm ; the thickness of the i-InGaN layer (14) is 100-800nm, the carrier concentration of the i-InGaN layer (14) is 1*10 -2*10 /cm , and the In component of the i-InGaN layer (14) is 15-90 percent; the thickness of the p-GaN layer (15) is 50-100nm and the hole concentration of the p-GaN layer (15) is 1*10 -6*10 /cm ; and grid Ni/Au ohmic electrodes (16) are distributed on the surface of the p-GaN layer (15), and an Al/Au ohmic electrode (17) is extracted from the right side of the surface of the n-GaN layer (15). According to the InGaN solar cell with the p-i-n sandwich structure, the short-circuited current and the open-circuited voltage of the cell are increased, and higher conversion efficiency is achieved; and the InGaN solar cell with the p-i-n sandwich structure can be used for solar photovoltaic power generation.

InGaN solar cell with p-i-n sandwich structure

High performance InAlN/GaN high electron mobility transistors for low voltage applications

In this paper, terahertz monolithic integrated waveguide (TMIW) transmission lines (TLs) are analyzed and fabricated based on wide bandgap semiconductor materials. The ignored parameters of TLs at low frequencies, such as the via-hole shape, the titanium/gold thickness and roughness, and the micropipe effect of material, are especially investigated based on the semiconductor fabrication technique and the terahertz-wave theory. Subsequently, the fine optimized TMIW-TL and the transition to grounded coplanar waveguide are fabricated. The measurement shows that the attenuation constant of a TL is as low as 0.19 dB/λg at 220 GHz. The proposed TMIW can provide electrical performance similar to the conventional air-filled waveguide, while it has only 10% of the volume, which indicates a great potential for future terahertz integrated systems.

Xiaohua Ma

Papers

Performance improvement after nitridation treatment in HfO2-based resistance random-access memory

InGaN solar cell with p-i-n sandwich structure

High performance InAlN/GaN high electron mobility transistors for low voltage applications

Terahertz monolithic integrated waveguide transmission lines based on wide bandgap semiconductor materials

Effects of Locations of Cellulose Nanofibers in Membrane on the Performance of Positively Charged Membranes