Electrical devices are proliferating, with applications in communications, computing, health and environmental monitoring, and entertainment. The quality of these devices has been increasing even as their size has decreased. But further advances may be held back because conventional battery configurations are relatively large or have insufficient power capacity.

Researchers at Pacific Northwest National Laboratory have designed a revolutionary microbattery no bigger than a grain of rice, yet with as much as a 50 percent increase in cell capacity and energy compared to conventional commercial batteries. The manufacturing methods for these batteries also simplify the fabrication process and lower the cost of mass production.

The design involves a cylindrical battery case of aluminum, copper, nickel, or stainless steel (or their alloys) housing the following components:

• An anode with an active material of lithium metal or its alloy pressed on a copper mesh and rolled into a cylinder.
• A cathode made of a mixture of powders, including carbon monofluoride or manganese dioxide. A carbon conductive additive can be included to increase the electrical conductivity of the mixture.
• An electrolyte in contact with the anode and the cathode; this electrolyte comprises lithium salts, solvents, and additives.
• A separator configured to electrically insulate the anode from the cathode while allowing the electrolyte to pass through.

Batteries can be fabricated without the slurry making and coating processes involved in conventional battery designs, thereby significantly reducing the cost and time needed for manufacturing. In addition, the direct use of electroactive powders eliminates the weight and volume of binder and current collector foils used in other batteries, improving cell-level capacity by as much as 50 percent.

APPLICABILITY

Batteries that provide increased energy capacities on a smaller scale for use in microelectronics remain in demand. PNNL’s microbattery could be used to power a host of electrical devices, such as the following:

• Downsized sensors for environmental or security monitoring
• Wearable devices for tracking movement or health
• Medical devices, such as pacemakers, hearing aids, defibrillators, and in vivo imaging systems.

The batteries have already been used successfully in animal acoustic telemetry transmitters to track the movements of many fish species, including salmon, lamprey, eel, and sablefish.