PREPARATION OF Bi₂O₃-DOPED NiO/YSZ ANODE MATERIALS FOR SOFCs

Abstract

The NiO/YSZ anode materials of SOFCs with Bi2O3 as sintering aids were successfully prepared by dry-pressing process. The effects of Bi2O3 content on the sintering properties of NiO/YSZ anode materials were studied, including the effects on the density, open porosity, weight loss, phase composition, microstructure, mechanical strength and electrical conductivity. In particular, the weight loss, relative density and bending strength of the sintered NiO/YSZ ceramics increased with the increase of Bi2O3 content while the open porosity decreased gradually. The density of the NiO–YSZ ceramics with 6[Formula: see text]wt.% Bi2O3 sintered at 1250[Formula: see text]C could reach that of the ceramics without Bi2O3 sintered at 1400[Formula: see text]C. For Bi2O3 concentration higher than 6[Formula: see text]wt.%, phase transformation of zirconia from monoclinic to cubic structure occurs, causing volume change and microcracks in the anode materials. Therefore, the optimum adding amount of Bi2O3 is 6[Formula: see text]wt.%, which can reduce the sintering temperature to 1250[Formula: see text]C. The ceramics with 6[Formula: see text]wt.% Bi2O3 have relatively high bending strength and low sintering temperature. This is of great significance for improving the performance of the anode and cutting the cost.

Preparation of Bi2O3–YSZ and YSB–YSZ Composite Powders by a Microemulsion Method and Their Performance as Electrolytes in a Solid Oxide Fuel Cell

“…Apart from the phase instability of δ-Bi 2 O 3 , doping of Bi 2 O 3 into YSZ also causes a crystallographic transformation of the stabilized cubic ZrO 2 into a monoclinic phase [31], especially when the sintering temperature is lower than 1300 • C. In addition, due to its low melting point, Bi 2 O 3 volatilizes during sintering and leaves pores inside grains or grain boundaries, which is detrimental to the whole performance of YSZ electrolytes [13]. This phenomenon becomes even worse if the particle size of Bi 2 O 3 is larger.…”

Influence of Sintering Temperature on the Structural, Morphological, and Electrochemical Properties of NiO-YSZ Anode Synthesized by the Autocombustion Route

“…In the case of NiO (nickel oxide)-YSZ (Y 2 O 3 -doped ZrO 2 , yttria-stabilized zirconia) based anode, nickel (after reduction) can easily oxidize different chemicals used as fuel, such as hydrocarbons, hydrogen, etc., and is responsible for the electronic transport to the external circuit [10,11]. The YSZ material not only supports the nickel particles but also takes part in ionic conduction and thermal expansion and is used to produce a proper networked structure necessary for the catalytic activity [12]. NiO, after reduction into Ni metal, plays a vital role to determine the structure and electronic conductivity of the anode.…”