C.F. Luck

Fabrication and characterization of amorphous lithium electrolyte thin films and rechargeable thin-film batteries

Amorphous oxide and oxynitride lithium electrolyte thin films were synthesized by r.f. magnetron sputtering of lithium silicates and lithium phosphates in Ar, Ar + O2, Ar + N2, or N2. The composition, structure, and electrical properties of the films were characterized using ion and electron beam, X-ray, optical, photoelectron, and a.c. impedance techniques. For the lithium phosphosilicate films, lithium ion conductivities as high as 1.4 × 10−6 S/cm at 25 °C were observed, but none of these films selected for extended testing were stable in contact with lithium. On the other hand, a new thin-film lithium phosphorus oxynitride electrolyte, synthesized by sputtering Li3PO4 in pure N2, was found to have a conductivity of 2 × 10-6 S/cm at 25 °C and excellent long-term stability in contact with lithium. Thin-films cells consisting of a 1 μm thick amorphous V2O5 cathode, a 1 μm thick oxynitride electrolyte film, and a 5 μm thick lithium anode were cycled between 3.7 and 1.5 V using discharge rates of up to 100 μA/cm2 and charge rates of up to 20 μA/cm2. The open-circuit voltage of 3.6 to 3.7 V of fully-charged cells remained virtually unchanged after months of storage.

Electrical properties of amorphous lithium electrolyte thin films

The impedance of xLi2O·ySiO2·zP2O5 thin films deposited by RF-magnetron sputtering was analyzed using two models in which the frequency dependence of the bulk response was represented by: (1) a Cole-Cole dielectric function and (2) a constant phase angle element. Increases in the conductivity with Li2O concentration and with addition of SiO2 to Li2O-P2O5 compositions are attributed to an increase in Li+ mobility caused by changes in the film structure. A new amorphous oxynitride electrolyte, Li3.3PO3.9N0.17, prepared by sputtering Li3PO4 in N2, has a conductivity at 25°C of 2×10−6S/cm and is stable in conta with lithium.

Sputtering of lithium compounds for preparation of electrolyte thin films

Abstract Several lithium compounds have been sputtered in a planar rf magnetron source. Lithium orthophosphate was observed to sputter normally and nearly stoichiometric films were obtained. Sputtering of lithium orthosilicate, however, resulted in extremely lithium deficient films. This was due to the decomposition of the target and the segregation of large amounts of Li 2 O to the unsputtered areas of the target.

New amorphous thin-film lithium electrolyte and rechargeable microbattery

Sputtering of Li/sub 3/PO/sub 4/ in pure N/sub 2/ results in the formation of an amorphous lithium electrolyte that is suitable in contact with lithium and has electrical properties that are suitable for application in a thin-film cell. Thin-film rechargeable lithium cells have been fabricated and characterized using this electrolyte between a lithium anode and an amorphous vanadium oxide cathode. The open circuit voltage of the cell is 3.6 to 3.7 V, and it has a capacity of 130 mu Ah/cm/sup 2/ when discharged to 1.5 V. The AC impedance of the cells measured at different stages of discharge indicate a significant decrease in internal resistance at about the midpoint of the discharge.<<ETX>>

Status Report on the Installation of the Warm Sections for the Superconducting Linac at the SNS

The SNS superconducting linac (SCL) consists of 23 cryomodules (CMs), with possibly 9 additional CMs being added for future energy upgrade from 1 GeV to 1.3 GeV[1, 2]. A total of 32 warm sections separate the comparatively short CMs, and this allows a CM exchange within 48 hours, in order to meet demanding beam availability specifications. The 32 warm section chambers are installed between each pair of CMs, with each section containing a quadrupole doublet, beam diagnostics, and pumping [3]. The chambers are approximately 1.6 m long, have one bellows installed at each end for alignment, and are pumped by one ion-pump. The preparation and installation of these chambers must be made under stringent clean and particulate-free conditions, in order to ensure that the performance of the SCL CMs is not compromised. This paper discusses the development of the cleaning, preparation, and installation procedures that have been adopted for the warm sections, and the vacuum performance of the system.

Plasma diagnostic studies of the influence of process variable upon the atomic and molecular species ejected from (1−x)Li4SiO4:xLi3PO4 targets during radio frequency magnetron sputtering

The deposition of thin‐film electrolytes is a critical step in the development of lithium microbatteries with the potential for circuit integration. We have performed a preliminary study of the rf‐magnetron sputtering of (1−x)Li4SiO4:xLi3PO4 targets used to deposit amorphous thin‐film electrolytes formed of the three‐component system Li2O–SiO2–P2O5. Mass and optical emission spectroscopies have been used to investigate the effects of target composition and the deposition conditions upon the atomic and molecular species ejected from the targets. The data provide important information for understanding the mechanism of film formation and for monitoring the Li atomic flux onto the substrates during film growth.

Spuiter Deposition of Lithium Silicate — Lithium Phosphate Amorphous Electrolytes

Thin films of an amorphous lithium-conducting electrolyte were deposited by rf magnetron sputtering of ceramic targets containing Li{sub 4}SiO{sub 4} and Li{sub 3}PO{sub 4}. The lithium content of the films was found to depend more strongly on the nature and composition of the targets than on many other sputtering parameters. For targets containing Li{sub 4}SiO{sub 4}, most of the lithium was found to segregate away from the sputtered area of the target. Codeposition using two sputter sources achieves a high lithium content in a controlled and reproducible film growth. 10 refs., 4 figs.