1 fuel cell
A fuel cell is a device that continuously inputs fuel to carry out a chemical reaction and directly converts chemical energy into electrical energy[4]. The fuel is usually methanol, ethanol, pure hydrogen, natural gas and gasoline.
Among ion exchange membrane fuel cells, those using hydrogen and oxygen as fuel are the most common. A special catalyst is used to react the fuel with oxygen to produce carbon dioxide and water. The fuel used in this process is cheap, the chemical reaction is not dangerous, the carbon dioxide emissions are much lower than those of general methods, and the water produced is harmless. It is a low-pollution energy source[5], which is unmatched by other power sources today. At present, computer and automobile companies have begun to focus on developing fuel cells to replace traditional battery power sources. The application of fuel cells in the automotive field has become an inevitable trend in energy development.
As an energy conversion device, fuel cell batteries work on the principle of galvanic cells, directly converting the chemical energy stored in fuel and oxidant into electrical energy. The reaction is essentially a redox reaction.
A fuel cell battery mainly consists of four parts: an anode, a cathode, an electrolyte, and an external circuit. Fuel gas and oxygen (air) are introduced to the anode and cathode, respectively. At the anode, the fuel gas releases electrons, which are then conducted to the cathode via the external circuit and combine with oxygen to form ions. Under the influence of an electric field, these ions are transferred through the electrolyte to the anode and react with the fuel gas, ultimately forming a circuit and generating electricity. Simultaneously, due to the reaction of the fuel itself and the battery's internal resistance, the fuel cell battery must dissipate a certain amount of heat to maintain a constant operating temperature. While it looks like a storage battery, it is essentially a power plant rather than a storage battery.
In this system, the anode and cathode not only conduct electrons but also act as catalysts for redox reactions. To facilitate the introduction of reactant gases and the removal of products, both electrodes often employ a porous structure. The electrolyte, on the other hand, plays a crucial role in transferring ions and separating fuel gas and oxidant gas, and is generally a dense structure.
As a conversion device, a fuel cell simply converts the chemical energy stored in fuel into electrical energy[7]. In principle, as long as chemical fuel is continuously supplied, a fuel cell can generate electricity continuously. This is the fourth generation of power generation technology after nuclear power, hydropower, and thermal power.
Fuel cell batteries have become a focus of attention for companies both domestically and internationally, primarily due to their inherent advantages:
High energy conversion efficiency;
Wide range of fuel options;
Clean and with minimal pollution;
Low noise;
High energy density and high reliability;
It has a fast load response and excellent adaptability.
Despite the many attractive advantages of fuel cells, there are still some shortcomings in their operation and promotion. One of the important problems is [9]:
High cost;
Power density still needs to be improved;
Fuel storage;
It is quite sensitive to environmental toxicity;
Limited operating temperature compatibility.
Currently, proton exchange membrane fuel cells and alkaline fuel cells are the most widely used. Proton exchange membrane fuel cells (PEMFCs) are a new generation of fuel cells that have developed rapidly in recent years. They have advantages such as high energy efficiency and energy density, small size and weight, fastest start-up speed, safe and reliable operation, and the widest range of applications. They are particularly widely used in automobiles. PEMFCs are commercial fuel cells under development.
