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

The combined effect of total ionizing dose (TID) and electrical stress is investigated on NMOSFETs. For devices bearing both radiation and electrical stress, the threshold voltage shift is smaller than those only bearing electrical stress, indicating that the combined effect alleviates the degradation of the devices. The H bond is broken during the radiation process, which reduces the participation of H atoms in the later stage of electrical stress, thereby reducing the degradation caused by electrical stress. The positive charges of the oxide layer generated by radiation neutralize part of the tunneling electrons caused by electrical stress, and consume some of the electrons that react with the H bond, resulting in weaker degradation. In addition, the positive charges in shallow trench isolation (STI) generated by radiation create parasitic leakage paths at the interfaces of STI/Si, which increase the leakage current and reduce the positive shift of the threshold voltage. The parasitic effect generated by the positive charges of STI makes the threshold voltage of the narrow-channel device degrade more, and due to the gate edge effect, the threshold voltage of short-channel devices degrades more.

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Combined Effect of TID Radiation and Electrical Stress on NMOSFETs

Degradation induced by holes in Si3N4/AlGaN/GaN MIS HEMTs under off-state stress with UV light


 This paper reports a low-damage interface treatment process for AlN/GaN high-electron-mobility transistors (HEMTs) and demonstrates the excellent power characteristics of radio frequency (RF) enhancement-mode (E-mode) AlN/GaN HEMTs. An RF E-mode device fabricated by remote plasma oxidation (RPO) treatment with 2.9-nm AlN barrier layer at 300 ℃. The device with a gate length of 0.12-μm has a threshold voltage (Vth) of 0.5 V, a maximum saturation current of 1.16 A/mm, a high Ion/Ioff ratio of 1*108, and a 440 mS/mm peak transconductance. During continuous wave (CW) power testing, it demonstrated a power added efficiency of 61.9% and a power density of 1.38 W/mm at 3.6 GHz, and a power added efficiency of 41.6% and a power density of 0.85 W/mm at 30 GHz. Furthermore, RPO treatment improves the mobility of RF E-mode AlN/GaN HEMTs. All results show that the RPO processing method has good applicability for scaling ultrathin barrier E-mode AlN/GaN HEMTs for 5G compliable frequency ranging from sub-6 GHz to Ka-band.

Low-Damage Interface Enhancement-mode AlN/GaN HEMTs with 41.6% PAE at 30 GHz

This work proposes a GaAs HBT Doherty power amplifier (DP A) with a compact size for 5G application. Different from most GaAs HBT DP As, this DPA operates in the asymmetric mode with an integrated three stages for higher gain, and the phase alignment between the carrier and peaking amplifier is enhanced by employing input, inter-stage and output matching network. The fabricated Doherty P A achieved a high gain of 32.5-34.1 dB and P1dB of 34-34.5 dBm. The 42.8-45 % and 28.7-30.9 % PAE are obtained at P1dB and 7 dB PBO under a continuous-wave signal test across 3.3-3.6 GHz respectively. At 3.5 GHz, a 10-MHz two-tone signal is also applied to the proposed DP A. The measured IMD3 is less than -30.2 dBc without any linearization.

A 3.3-3.6 GHz Doherty Power Amplifier in GaAs HBT Technology with an Asymmetric Structure

This work thoroughly analyzed and studied the natural benefits of InAlN/GaN double channel (DC) HEMTs over single channel (SC) HEMTs in terms of increased linearity. When the drain-source current (Ids) is increased in an SC-HEMT, a strong electric field (E-field) will intensify the carrier scattering effect, which causes severe mobility (μ) degradation. Based on the above, combined with a sharp increase in source access resistance (Rs), causes the non-intrinsic transconductance to roll off quickly, making transconductance (Gm) flattening difficult to accomplish. Due to its strongly polarized material, a thin barrier was adopted to provide enough carrier concentration, which improves gate control ability, and its double-channel structure, which offers additional carrier transport channels and disperses the channel E-field distribution, the InAlN/GaN DC-HEMT effectively addresses the aforementioned issues. Furthermore, the theoretically calculated OIP3 value of this device is constant over a large range of gate-source voltage (Vgs), making it a workable option for enhancing the linearity of power microwave GaN-based HEMTs.

Xiaohua Ma

Papers

Combined Effect of TID Radiation and Electrical Stress on NMOSFETs

Degradation induced by holes in Si3N4/AlGaN/GaN MIS HEMTs under off-state stress with UV light

Low-Damage Interface Enhancement-mode AlN/GaN HEMTs with 41.6% PAE at 30 GHz

A 3.3-3.6 GHz Doherty Power Amplifier in GaAs HBT Technology with an Asymmetric Structure

Investigation of InAlN/GaN Double Channel HEMTs for Improved Linearity