Metallization and Diffusion Bonding of CoSb3-Based Thermoelectric Materials

Abstract

CoSb3-based skutterudite alloy is one of the most promising thermoelectric materials in the middle temperature range (room temperature—550 °C). However, the realization of an appropriate metallization layer directly on the sintered skutterudite pellet is indispensable for the real thermoelectric generation application. Here, we report an approach to prepare the metallization layer and the subsequent diffusion bonding method for the high-performance multi-filled n-type skutterudite alloys. Using the electroplating followed by low-temperature annealing approaches, we successfully fabricated a Co-Mo metallization layer on the surface of the skutterudite alloy. The coefficient of thermal expansion of the electroplated layer was optimized by changing its chemical composition, which can be controlled by the electroplating temperature, current and the concentration of the Mo ions in the solution. We then joined the metallized skutterudite leg to the Cu-Mo electrode using a diffusion bonding method performed at 600 °C and 1 MPa for 10 min. The Co-Mo/skutterudite interfaces exhibit extremely low specific contact resistivity of 1.41 μΩ cm2. The metallization layer inhibited the elemental inter-diffusion to less than 11 µm after annealing at 550 °C for 60 h, indicating a good thermal stability. The current results pave the way for the large-scale fabrication of CoSb3-based thermoelectric modules.

Multiple-Filling-Induced Full-Spectrum Phonon Scattering and Band Convergence Leading to High-Performance n-Type Skutterudites

“…We prepared a Co− Mo metallization layer on the surface of n-type skutterudites by electroplating and then jointed the metallized skutterudites to the Mo50Cu50 electrode using a diffusion bonding method. 55 The Co−Mo/skutterudite interfaces exhibited a satisfactory specific contact resistivity of 6.13 μΩ cm 2 after annealing at 823 K for 60 h. Based on the above-measured data and the literature, 56,57 10 μΩ cm 2 is a reasonable ρ c value to simulate the real service state. Figure 7c depicts the η max as a function of the cross-sectional area ratio of n-type and the p-type leg (A n / A p ) under different operating temperatures.…”

“…Moreover, it is indispensable to minimize the ρ c via interface optimization. We prepared a Co–Mo metallization layer on the surface of n-type skutterudites by electroplating and then jointed the metallized skutterudites to the Mo50Cu50 electrode using a diffusion bonding method . The Co–Mo/skutterudite interfaces exhibited a satisfactory specific contact resistivity of 6.13 μΩ cm 2 after annealing at 823 K for 60 h. Based on the above-measured data and the literature, , 10 μΩ cm 2 is a reasonable ρ c value to simulate the real service state.…”

Doping Effect on Cu2Se Thermoelectric Performance: A Review

“…From Equation (1), ZT has a strong relationship with temperature T, thus, according to the optimum operating temperature, the thermoelectric materials are divided into three groups, which are: low temperature ( ) TE materials: Bi 2 Te 3 series; mid temperature ( ) TE materials represented by PbTe series; high temperature (>900 ) TE materials which are represented by SiGe series. These series of materials have already achieved high figure of merit (ZT) values, and are applied in some certain field [ 12 , 13 , 14 , 15 , 16 ]. For instance, SiGe and PbTe series of TE materials, using radioisotope as heat source, have been used in space domains.…”

Research Progress of Interfacial Design between Thermoelectric Materials and Electrode Materials

“…In order to reduce the mismatch of thermal expansion coefficient and contact resistivity, a Co−Mo metalization layer was fabricated on the surface of the CoSb 3 , and then it was joined to the Cu−Mo electrode using a diffusion bonding method. 75 The diffusion layer did not reduce the mechanical strength of the joint, and these joints exhibited an extremely low specific contact resistivity. Recently, CuMo/ Ni/FeCoNiCrMo/Ce 0.8 Fe 3 CoSb 12 joints were designed and bonded by using multiple intermediate layers.…”