Question

(a) What is the difference between a battery and a fuel cell? (b) Can the "fuel" of a fuel cell be a solid? Explain.

Short answer

(a) The main difference between a battery and a fuel cell is that a battery stores energy within the cell and can be recharged, while a fuel cell generates electricity continuously as long as fuel and an oxidizer are supplied to it. Batteries typically have a limited lifetime due to the degradation of internal components, while fuel cells can have a longer lifespan with a maintained fuel supply. (b) Yes, the fuel of a fuel cell can be a solid, as illustrated by solid oxide fuel cells (SOFCs) which use solid fuels such as metal powders or metal oxides. In SOFCs, the solid fuel is converted into a gas (usually hydrogen), which then reacts with oxygen to generate electricity. The use of solid fuels makes SOFCs more versatile and efficient than other fuel cells that rely solely on gaseous fuels.

Step-by-step solution

Part (a): Difference between a battery and a fuel cell

A battery is an electrochemical device that stores energy, generates electricity by moving electrons through an external circuit, and can be recharged multiple times. On the other hand, a fuel cell is an electrochemical device that converts chemical energy from a fuel into electricity through a reaction between the fuel and an oxidizing agent, typically oxygen. The main difference between a battery and a fuel cell is that a battery stores its energy in the cell itself, while a fuel cell generates electricity continuously as long as fuel and an oxidizer are supplied to it. Additionally, batteries generally have a limited lifetime due to the gradual degradation of their internal components, while fuel cells can have a longer lifespan as long as the fuel supply is maintained.

Part (b): Can the fuel of a fuel cell be a solid?

Yes, the fuel of a fuel cell can be a solid. Solid oxide fuel cells (SOFCs) are an example of fuel cells that utilize solid fuels. These fuel cells use a solid oxide, typically a ceramic material, as the electrolyte. The solid fuel, usually in the form of metal powders or metal oxides, reacts with an oxidizing agent at high temperatures (around 800-1000°C) to generate electricity. In SOFCs, the solid fuel is converted into a gas (usually hydrogen) within the cell itself, which then reacts with oxygen to generate electricity. The use of solid fuels in fuel cells allows for a wider range of fuel options, including biomass, syngas, and other hydrocarbons, making SOFCs more versatile and efficient than other types of fuel cells that rely solely on gaseous fuels.