pH-gradient Graphic
An artistic representation of the pH-gradient enabled microscale bipolar interface (PMBI).

Engineers developed a direct borohydride fuel cell that operates at double the voltage of today’s commercial fuel cells. Using a pH-gradient-enabled microscale bipolar interface (PMBI), the fuel cell can be used in high-power applications such as drone flight, and eventually electric aircraft.

The fuel cell uses an acidic electrolyte at one electrode and an alkaline electrolyte at the other electrode. The PMBI keeps the acid and alkali from mixing, forming a sharp pH gradient and enabling the successful operation of the system.