Fuel cell is a kind of high efficiency and low pollution power generation device. Compared with traditional power generation system, fuel cell has the advantages of high efficiency, stability, wide range of fuel application, less pollutants and low noise. Anode material is an important part of fuel cell, which should have good chemical stability and be compatible with other components. In addition, the anode material should have certain strength and thermal shock resistance.
- Conventional carbon anode: Conventional carbon anodes mainly include carbon paper, carbon cloth, graphite and others. These conventional carbon anodes are cheap and have excellent electrical conductivity and good corrosion resistance. Carbon paper is hard and brittle, which makes it easy to connect wires. Carbon cloth is porous and softer than carbon paper. As typical representatives of plate electrodes, they can improve the performance of fuel cell by reducing the distance between anode and cathode electrodes. Moreover, the conductivity of graphite is excellent.
- Metal anode: Some noble metals and transition metals, such as Ni, Pt, Co and Ti, can be used as anode materials for fuel cells because of their high activity. Furthermore, considering volatility, chemical stability, catalytic activity and cost, Ni has outstanding advantages as a fuel cell anode material.
- Cermet anode: In order to optimize the performance of metal anode material, porous cermet anode can be prepared by dispersing in yttria-stabilized zirconia (YSZ) matrix. Ni/YSZ porous cermet is the most commonly used anode materials for fuel cells. Ni is not only a good catalyst for reforming catalytic reaction and hydro-electrochemical oxidation reaction, but also the cost of Ni is lower than Co, Pt, Pd and others. In addition, YSZ is generally used as the matrix of Ni. Ni and YSZ do not fuse or interact with each other in a wide temperature range. After treatment, a good microstructure can make the material stable for a long time. More importantly, good microstructure and material composition can improve the electrochemical activity of anodic materials for interfacial reactions. The preparation process and microstructure of porous Ni/YSZ cermet have a significant impact on their properties. Therefore, many studies have improved the preparation process of Ni/YSZ to obtain satisfactory electrode microstructure to further improve the anode performance.
Figure 1. Schematic illustration of a porous cermet anode.
- Others: Other commonly used anode materials include carbon nanotubes and their complexes, oxides, graphene materials and others. Carbon nanotubes have specific pore structure, high mechanical strength, large specific surface area, good thermal stability and high electrical conductivity. Carbon nanotubes can effectively reduce the anode internal resistance of fuel cells. In addition, two-dimensional nano-graphene materials with unique functions are popular in the field of fuel cell materials due to their large specific surface area, excellent electrical conductivity, good mechanical strength and high electro-catalytic activity. Moreover, the typical representative of oxide anode materials are CeO2 and the modified materials based on CeO2. Furthermore, graphene can be formed by chemical oxidation without toxic metal catalysts. Therefore, graphene anode materials are environmentally friendly.
Figure 2. An example of CeO2 anode for fuel cell.
- Wang W, Su C, Wu Y, et al. Progress in solid oxide fuel cells with nickel-based anodes operating on methane and related fuels[J]. Chemical Reviews, 2013, 113(10):8104-8151.
- Fan Y, Chen G, Xi X, et al. Co-generation of ethylene and electricity from ethane by CeO2/RP-PSCFM@CoFe anode materials in proton conductive fuel cells[J]. ACTA PHYSICO-CHIMICA SINICA, 2020:2009107.