Not a battery, not a cap: Murata’s small energy [storage] device

October 01, 2015 // By Graham Prophet
To meet what the company sees as a gap in the available range of energy storage solutions, Murata has developed the UMAC, a small, high-capacity cylinder-type energy device for use in wearable and wireless sensor applications. Although lithium-ion based, Murata differentiates it from a battery.

The UMAC is a miniature device with a high energy storage capacity, low internal resistance, fast charging and discharging and the ability to withstand load fluctuations. It may be used as a secondary battery in the same way as a capacitor. The UMAC achieves better charge/discharge characteristics and has an extended cycle life superior to conventional batteries. Suited for use as a power supply for wearable devices or sensor nodes for wireless sensor networks, the UMAC maintains flat voltage characteristics while accommodating a wide range of load characteristics.

Designed for applications within the wearables market, the UMAC has several key safety features. Because of its small capacity and use of chemically stable materials, thermal runaway does not occur. This means that smoke or fire will not occur should a short circuit happen. The UMAC has a high rate of charge/discharge cycles and is capable of 10 cycles per hour with a maximum discharge rate of 30 mA. It also features an extended cycle life with a capacity recovery rate of 90% or higher after 1,000 cycles.

The UMAC is particularly suitable as an energy device for sensor nodes within wireless sensor networks because high-rate discharge characteristics mean that peak-assist capacitors are not required. Low self-discharge level minimises loss of stored energy and flat voltage characteristics permit use immediately after charging starts for stable device operation.

Another application is as a power supply for digital pens or wearable devices. This is because long cycle-life characteristics enable repeated use after rapid charging and also because chemically stable composition allows small size and safe packaging. Other uses include backup power supply for electric home appliances and electronic devices such as mobile phones and information terminals.

Murata Electronics; www.murata.com