Fabrication of the planar-type CO2 gas sensor using an evaporated Li3PO4 film and its sensing characteristics

Jeong, Chaehwan; Song, Ho-Gun; Chang, Duck-Rye; Kim, Ho‐Sung

doi:10.1007/s12540-009-0101-0

Cited by 9 publications

(11 citation statements)

References 13 publications

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“…[4][5][6] Also optical humidity sensors based on Li 3 PO 4 have been presented recently. 7 Thin Li 3 PO 4 film has also been used as an interfacial layer between LiCoO 2 electrode and solid polymer electrolyte in solid state lithium ion battery.…”

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confidence: 99%

Lithium Phosphate Thin Films Grown by Atomic Layer Deposition

Hämäläinen

Holopainen

Munnik

et al. 2012

J. Electrochem. Soc.

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Lithium phosphate, Li 3 PO 4 , has been considered a potential electrolyte material for lithium ion batteries and CO 2 sensors in particular if the films can be made dense and of high quality already at low thickness. In this work, Li 3 PO 4 thin films were deposited by atomic layer deposition (ALD) between 225 and 350 • C using trimethyl phosphate and either of the two lithium sources, namely lithium hexamethyldisilazide or lithium tert-butoxide. The deposited films showed slightly crystalline Li 3 PO 4 structure in X-ray diffraction and the elastic recoil detection analysis confirmed this stoichiometry with some carbon and hydrogen impurities. The crystallinity and thermal stability of the films at elevated temperatures in N 2 were also examined. The long term stability of the deposited Li 3 PO 4 films under ambient air may be an issue for the applicability of these processes. Lithium phosphate, Li 3 PO 4 , can be applied as an electrolyte in solid state lithium ion batteries 1-3 and CO 2 gas sensors. 4-6 Also optical humidity sensors based on Li 3 PO 4 have been presented recently. 7 Thin Li 3 PO 4 film has also been used as an interfacial layer between LiCoO 2 electrode and solid polymer electrolyte in solid state lithium ion battery. 8 Crystallization of Li 3 PO 4 greatly decreases the ionic conductivity: amorphous Li 2.7 PO 3.9 has an ionic conductivity of 6.6 × 10 −8 S/cm while the polycrystalline γ-Li 3 PO 4 has been extrapolated to be highly resistive with as low conductivity as 4.2 × 10 −18 S/cm at 25 • C. 9 Even if the ionic conductivity is only moderate, amorphous Li 3 PO 4 is still a potential electrolyte material provided it can be made dense already at low thickness.In lithium ion battery applications the 3D structuring of the materials would be a way to effectively increase the energy storage capacity by increasing the specific surface area. 10, 11 Atomic layer deposition (ALD) 12-15 may prove to be useful for depositing thin films on demanding 3D structures as films grown by ALD inherently possess good conformality and uniformity because of the alternating, saturative precursor doses and self-limiting surface reactions. The resulting accurate thickness controllability and repeatability of the films is a major benefit of the layer by layer approach used in ALD. Some of the electrolyte material candidates for 3D batteries include for example Li 3 PO 4 and nitrogen mixed lithium phosphate known as LiPON. 10,11 ALD processes for phosphate films are very few in number, although aluminum phosphate thin films have been deposited already in the 90's. 16,17 Besides aluminum phosphate, only ALD of calcium phosphate has been published. 18 Also lithium containing ALD processes were absent until recent reports on ALD of lithium hydroxide, lithium carbonate, lithium aluminate, lithium silicate, lithium lanthanate and lithium lanthanum titanates. [19][20][21][22][23] In addition, ALD of LiFePO 4 and Ca:LaPO 4 materials have been recently presented. 24,25 Here we report ALD growth and characterization of lithium...

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confidence: 99%

Lithium Phosphate Thin Films Grown by Atomic Layer Deposition

Hämäläinen

Holopainen

Munnik

et al. 2012

J. Electrochem. Soc.

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“…Among these researches, the sensors with a lithium ion transporting solid electrolyte and two electrodes (a sensing electrode and a reference electrode) have been paid much attention for their good sensing performances [8][9][10]. CO 2 sensors based on bulk-type or film-type Li 3 PO 4 were reported [11][12][13][14][15][16]. The film-type sensor can be miniaturized for low power consumption as well as low cost applications.…”

Section: Introductionmentioning

confidence: 99%

Influence of substrate surface roughness on the properties of a planar-type CO<inf>2</inf> sensor using evaporated Li<inf>3</inf>PO<inf>4</inf> film

Wang

Sun

Jiang

2013

The 8th Annual IEEE International Conference on Nano/Micro Engineered and Molecular Systems

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Planar-type potentiometric CO 2 gas sensors using thermal evaporated Li 3 PO 4 thin film as the solid electrolyte were fabricated. Al 2 O 3 plates with rough and smooth surfaces were used as the substrates of the sensors. X-ray diffraction analysis, atomic force microscope and scanning electron microscope were used to characterize the Li 3 PO 4 films. The sensing properties were investigated in the range of 500~5000 ppm CO 2 concentrations at 480 °C. Both the rough substrate sensor (rsensor) and the smooth substrate sensor (s-sensor) showed a good Nernst behavior. The output EMF of s-sensor showed a more stable signal than the r-senor. Response and recovery times of the r-sensor were 40 s and 75 s, and for the s-sensor they were 35 s and 60 s. The ΔEMF/decade values obtained from the r-sensor and s-sensor were 45 mV/decade and 55 mV/decade, respectively. It can be found that the Nernst's slop of the s-sensor was closer to the theoretically value. The results revealed that the substrate surface roughness may influence the characteristics of Li 3 PO 4 film and the response properties of the sensors to CO 2 .

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“…The lithium phosphate film doped with nitrogen is the most widely used electrolyte membrane in solidstate thin film lithium battery. Lithium phosphate has also been reported as sensors to CO 2 gases [11][12][13][14]. Among them, Kim's group [14] studied its electro-chemical sensing performances to CO 2 gas based on the Li 3 PO 4 film prepared by a thermal evaporation.…”

Section: Introductionmentioning

confidence: 99%