Search

Plasma-sputtered amorphous films for all-solid-state Li+-ion batteries are investigated. In LiPON electrolyte films, the amount of N incorporated into LiPO films is controlled by the sputtering discharge gas. Ionic conductivity increases with increasing N2 gas proportion in Ar/N2 discharge, reaching a maximum of 2.7 × 10−6 S/cm at Li2.39PO3.71N0.13. In amorphous LiAlGePO electrolyte films, the amounts of Al and Ge incorporated into LiPO films are controlled in a combinatorial approach using two-source co-sputtering. The P/Ge ratio varies over a wide range from 23.3 to 1.61 at the radial substrate positions, and the highest ionic conductivity of 4.32 × 10−5 S/cm is achieved at Li4.80Al0.80Ge1.16P3O13.1. We evaluate all-solid-state Li+-ion batteries fabricated using the developed amorphous LiPON electrolyte and GeSn anode films, where GeSn films with about 50 nm nanograins are fabricated by high-gas-pressure sputtering at 500 mTorr. A maximum capacity of 2.86 µAh/cm2 is attained for all-solid state Li+-ion battery.

We fabricated nanostructured Ge and GeSn films in He radio-frequency magnetron plasma sputtering deposition. Monodisperse amorphous Ge and GeSn nanoparticles of 30-40 nm in size were orderly arranged without aggregation by off-axis sputtering deposition in high He-gas-pressure range of 0.1 Torr. The Ge film porosity was over 30%. We tested the charge/discharge cycle performance of Li-ion batteries with nanostructured Ge and GeSn anodes. The Ge anode with an ordered arrangement of nanoparticles showed Li-storage capacity of 565 mAh/g after the 60th. The capacity retention was markedly improved by the addition of 3at% Sn in Ge anode. GeSn anode (3at% Sn) achieved a higher capacity of 1,128 mAh/g after 60th cycles with 92% capacity retention. Precise control of the nano-morphology and electrical characteristics by a single step procedure using low temperature plasma is effective for stable cycling of high-capacity Ge anodes.

Dense sintered bodies of proton conducting BaZrO3 (BZ) and Y-doped BaZrO3 (BZ-Y) were obtained at 1600℃ for a short sintering time of 5 hours, by the addition of NiO as a sintering promotion agent. The relative density and grain growth of samples, Ni-doped BaZrO3 (BZ-N) and Ni, Y co-doped BaZrO3 (BZ-NY), were increased with increasing Ni addition. The sinterability of BZ-NY was greatly improved just to add only 0.6 mol% Ni and the relative density of this sample was more than 98%, in contrast to that of 60% at most for BZ-Y without Ni addition. Electrical conductivity of BZ-NY added Ni 1.0 mol%, BaZr0.91Ni0.01Y0.08O3-α, was more than 10-3 S.cm-2 at 900℃ in a wet 1% hydrogen atmosphere, which value was 10 times higher than that of BZ-Y. In addition, the kind of electrical conduction carrier and an ionic transport number were also examined by employing various concentration cells. It was found that the proton conduction was dominant for both BZ-N and BZ-NY samples, although BZ-NY showed scarcely oxygenion conduction approximately 10% in a high temperature range higher than 800℃. From these results, as mall amount of Ni addition found to be effective for improvement of both the sinterability and the electrical conductivity.

We present a study on morphological control of nanostructured Ge films by the Ar gas pressure in plasma sputtering deposition. In the low Ar-gas-pressure range, aggregated islands of amorphous grains are formed on the film surface, while in the high-pressure range of 500 mTorr monodisperse nano-grains of about 30 nm in size are orderly arranged without aggregation. The film porosity shows a high value of over 10%. We tested the charge/discharge cycle performance of Li-ion batteries with nanostructured Ge films as anodes. The battery cell with an ordered arrangement structure maintained a high capacity of 434 mAh g−1 after 40 charge/discharge cycles, while that with an aggregated structure exhibited a rapid degradation of capacity to 5.08–183 mAh g−1. An ordered arrangement of Ge nano-grains with a high porosity, which is realized in a simple one-step procedure using high Ar-gas-pressure plasma sputtering, is effective for the stable cycling of high-capacity metal anodes.

In-free and In-added MgB 2 thick films were prepared on ceramic substrates (MgO, YSZ, SrTiO 3 and Al 2 O 3 ) using a simple screen printing method. For In-free films, the adhesion between the films and the substrates were very weak; about 10–40% of these films peeled off after firing. We examined the temperature dependence of the resistivity using the non-separated films. These films showed metallic behavior from room temperature to T c(onset) = 39.7 K and attained zero resistivity at T c(end point) = 34.0–37.7 K, depending on the kinds of substrate. For In-added films formed on MgO, almost all films adhere well to the substrates and the transport J c (4.2 K, 0 T) were also improved remarkably; 70 A cm −2 for In-free film and 1.6 × 10 3 A cm −2 for 18 vol.% In film.

High- T c screen-printed Ho–Ba–Cu–O films were prepared on YSZ substrates by a melt processing method. The films were fired at T s = 1000–1050 °C for 5 min and cooled to 450 °C by two steps in flowing O 2 . The maximum critical current density J c (77 K, 0 T) of 2.0 × 10 3 A cm − 2 was only attained under much limited firing conditions; T s = 1020 °C and cooled to 800 °C at a cooling rate of 400 °C h − 1 .