Thermoelectric generator and solid-state battery for stand-alone microsystems

Abstract

This paper presents a thermoelectric (TE) generator and a solid-state battery for powering microsystems. Prototypes of TE generators were fabricated and characterized. The TE generator is a planar microstructure based on thin films of n-type bismuth telluride (Bi 2 Te 3) and p-type antimony telluride (Sb 2 Te 3), which were deposited using co-evaporation. The measurements on selected samples of Bi 2 Te 3 and Sb 2 Te 3 thin films indicated a Seebeck coefficient in the range of 90-250 µV K −1 and an in-plane electrical resistivity in the range of 7-17 µ m. The measurements also showed TE figures-of-merit, ZT, at room temperatures (T = 300 K) of 0.97 and 0.56, for thin films of Bi 2 Te 3 and Sb 2 Te 3 , respectively (equivalent to a power factor, PF, of 4.87 mW K −2 m −1 and 2.81 mW K −2 m −1). The solid-state battery is based on thin films of: an anode of tin dioxide (SnO 2), an electrolyte of lithium phosphorus oxynitride (Li x PO y N z , known as LiPON) and a cathode of lithium cobaltate (LiCoO 2 , known as LiCO), which were deposited using the reactive RF (radio-frequency) sputtering. The deposition and characterization results of these thin-films layers are also reported in this paper.

Integrated Powder-Based Thick Films for Thermoelectric, Pyroelectric, and Piezoelectric Energy Harvesting Devices

“…The values of ZT reported for the co-evaporated films were in the region of 0.26-0.97 [25], [9] and comparable to those of the corresponding bulk materials. There have been fewer reports of powder-based thick film processing techniques [29], [30], [31], [32], [33], [34] such as screen printing, being used due to the tendency of alloy films to oxidise during the high temperature processing used.…”

“…The majority of reports of film based energy harvesters have focused on Bi 2 Te 3 /Sb 2 Te 3 materials deposited by co-evaporating [9], [28], [25] thin films (1-1.5 µm thick) to create in-plane architectures or electroplating [27], [26] thick films (50-70 µm) to create π architectures. The values of ZT reported for the co-evaporated films were in the region of 0.26-0.97 [25], [9] and comparable to those of the corresponding bulk materials.…”

“…Likewise there also exist a number of technologies to convert heat into electrical energy including turbine technologies, heat engines, thermionic emitters and thermoelectric generators. Of these thermoelectric generators offer the advantages of an absence of moving parts, quiet operation, light weight, scalability, and the ability to harvest energy from relatively low temperature sources [9], [10]. While frequently used for temperature control, thermoelectric generators (TEG) typically exhibit efficiencies around 10% making them attractive for EH and energy recovery applications despite being ill-suited for primary energy generation applications [11].…”

Micro-Power Generation Characteristics of Thermoelectric Thin Film Devices Processed by Electrodeposition and Flip-Chip Bonding

“…[1][2][3][4][5][6][7][8][9] As a promising energy harvesting method, thermoelectric power generation using a thin film device has drawn much attention because it can be operated with a small temperature difference produced by waste heat or by small heat source, such as body heat, in addition to its advantages of high power density, no moving parts, long lifetime, and high reliability. [1][2][3][4][5][6][7][8][9] A thermoelectric thin film device can be classified as having either an in-plane or cross-plane configuration based on the direction of heat flow through the device. 2,8,9 Compared to the in-plane thin film device, the crossplane device is more suitable for a micro-thermoelectric generator because of its low electrical resistance and lack of parasitic heat flow through the substrate.…”

Thermoelectric Thin Film Device of Cross-Plane Configuration Processed by Electrodeposition and Flip-Chip Bonding

“…16) To utilize the thermoelectric devices as micro power sources, it is required to dramatically reduce the size of the thermoelectric devices by employing thin-film technique and photolithography. 1,2,510) A thermoelectric thin film device can be classified as either the in-plane type or the cross-plane configuration according to the heat flow direction through the device. 2,810) Compared to the in-plane type, the cross-plane device has advantages of low electrical resistance and no parasitic heat flow through a substrate.…”