The batteries needed to power medical implants, drones, consumer electronics and other devices are shrinking in size to accommodate these applications but at the expense of energy density. The need to pack more power into a compact battery footprint has spurred researchers to design and package microbatteries that maximize energy density at the smallest sizes.

The design incorporates a new current collector and cathode element that increase the fraction of materials that store energy while serving as a protective shell, reducing the need for non-conductive packaging that normally prevents water and oxygen from penetrating the device. The cathode materials are electroplated The redesigned microbattery delivers four times the energy density of available batteries and weighs the same as two grains of rice. Source: University of Pennsylvaniadirectly onto thin metal foils that also function as the casing.

The resulting reduction in porosity and air gaps relative to conventional cathode structures allows lithium ions to travel quickly and directly through the cathode and into the device. Because the ions can travel far more efficiently through the cathode, it can be made far thicker without compromising on this key attribute, which in turn doubles the amount of energy-storing chemicals it can contain. The redesigned microbattery described in Advanced Materials delivers an energy density four times that of the current-state-of-the-art designs and weighs the same as two grains of rice.

The research was conducted by scientists from the University of Pennsylvania, University of Illinois and Xerion Advanced Battery Corp (Ohio).