In order to make solid oxide fuel cells (SOFCs) more economically feasible, researchers are studying how to reduce the cost to produce these fuel cells. One method that researchers are using to reduce that production cost is to reduce the operating temperature of the fuel cell from ~1000°C to 600°C. Producing SOFCs with proton-conducting materials leads to many advantages that can make the overall device more economical. One major benefit of using these materials is the ability to operate the fuel cell at lower temperatures with no significant negative impact on conductivity as a result of the perovskite structure of these materials[1]. By using the lower operating temperature, it is possible to utilize more inexpensive materials for the internal components of the SOFC. Rather than using ceramic supports or high temperature alloy materials which can increase the cost of the SOFC, it is possible to use more inexpensive steels as a support for the cell. With the lower operating temperature, these materials would not degrade as fast as in traditional SOFCs and will allow for a longer lifespan and less degradation of the fuel cell. In order to further decrease the cost of the cell production, it is also possible to incorporate internal reforming which can allow the use of methane as a fuel rather than hydrogen at the lower operating temperatures.

In this work, we will examine the use of Reactive Spray Deposition Technology (RSDT) as a method to produce these metal-supported proton-conducting solid oxide fuel cells. Use of the RSDT process in the production of low-temperature SOFCs has been well-documented, as previous studies show that the RSDT was able to deposit porous electrodes as well as dense electrolytes with satisfactory electrochemical performance [2]. The RSDT process allows for a direct deposition of the desired electrode and electrolyte materials onto a stainless steel or Crofer 22 APU® support and subsequent layers. In an effort to prevent oxidation of the metal supports, previous work has examined using diffusion blocking layers to allow for to use of Crofer 22 APU® in an RSDT application [3]. This work will use the proton conducting material Ba(Zr_0.4Ce_0.4Y_0.1Yb_0.1)O₃ (BZCYYb4411) as the electrolyte material. Previous studies using BZCYYb have shown excellent ionic conductivity below 750°C [4]. Data from Yang et al. shows that the ionic conductivity of BZCYYb is significantly greater than the conductivity of yttria-stabilized zirconia, a traditional oxygen anion conducting SOFC material, at the same temperature [4]. That BZCYYb electrolyte is deposited on a Ni-BZCYYb cermet anode with an La_0.6Sr_0.4Co_0.2Fe_0.8O₃ (LSCF6428) cathode. Following each deposition, the deposited layers are examined using scanning electron microscopy to check that each RSDT-deposited layer has the desired morphology, as shown in Figure 1. This work examines those cells and demonstrates the electrochemical performance given by the RSDT-produced metal-supported proton-conducting SOFCs.

References

[1] E.C.C. de Souza, R. Muccillo. Materials Research 13 (2010) 385-394.

[2] R. Maric, K. Furuskai, D. Nishijima, R. Neagu. ECS Transactions 35 (2011) 473-481.

[3] R. Nedelec, R. Neagu, S. Uhlenbruck, R. Maric, D. Sebold, H.-P. Buchkremer, D. Stover. Surface & Coatings Technology 205 (2011) 3999-4004.

[4] L. Yang, S. Wang, K. Blinn, M. Liu, Z. Liu, Z. Cheng, M. Liu. Science 326 (2009) 126-129.