PORTFOLIO

Permeability in battery components

Components used in the construction of a battery or fuel cell may be exposed to strong chemicals, high pressures and raised temperatures. In developing new and better products, it is essential to study the behaviour of components under different conditions – and component permeability is a key factor. To measure permeability of components in batteries, the developers use liquid permeameters and gas permeameters.

The battery and fuel cell industry’s constant quest is to develop products that are more efficient, compact, powerful and cost-effective. New components and materials are constantly being tested to assess their suitability and performance in the battery environment. One of the developers’ particular goals is to raise the temperature at which fuel cells operate, to boost the efficiency of their electrochemical processes.

Chemicals to which battery components may be exposed, and which may pass through their porous structure, include strong alkaline solutions like saturated KOH, and acids like phosphoric acid, as well as saline and other salts. Their effects on the materials can include reduction in pore size, due to deposition of salt in them, and distortion of pores due to saturation and swelling. Permeability will be affected accordingly.

If battery components are operating under high pressure, it is possible that their pores may be stretched or, alternatively, compressed. In either case pore size – and hence permeability – will be altered.

Elevated temperatures can alter the properties of the fluids as well as the pore structure of the components, both of which may affect permeability.

In fact, the three factors above – chemicals, pressure and temperature – interact with each other to produce a variety of effects on pore size and permeability.

In studying battery materials and components, it is essential that the permeameter should allow for these conditions to be reproduced and varied. In this way, their porous nature and properties can be assessed in the circumstances they will face during operation.