STMicroelectronics' EnFilm ultrathin solid-state battery has fast constant-voltage recharge and lasts more than 10 years.

The latest generation of devices stimulates parallel development in power storage solutions.

Batteries hold the key to the rise of wearable electronics, which will require ultrahigh energy density and low capacity. The form factor is also extremely important for tiny systems and devices such as smartwatches, Google Glasses and wristbands, for which mechanical design and aesthetic perception are critical. Component suppliers are going to play a crucial role in this new power dynamics as the battery takes the centerstage.

Wearable electronics is an exciting and emerging product category. It represents a continued evolution along the lines of mobile and portable devices that began in the Li-ion Age of the 1990s.

Since then, bulky brick phones have become thin and light while offering radically greater capability.

Next up, large, heavy notebook computers have transformed into slim ultrabooks and high-performance tablet PCs. All this has required continuous improvement in both battery technology as well as portable power management.

“Wearable devices really are just continuing down the same path,” said Upal Sengupta, marketing manager for Portable Power at Texas Instruments Inc. “Now that we can generate and process power with very thin solutions such as high-frequency DC-DC converters with low-profile magnetics, we can continue to embed electronic functionality in increasingly smaller systems.”

The semiconductor industry cannot really push the battery designs all by itself. Nevertheless, its emphasis remains on minimizing chip size and the number of external components required for total power management solutions while maximizing the efficiency of energy conversion from the battery to the system.

“We can help enable the design of ultrasmall and -low power systems by providing correspondingly compact power management circuits,” Sengupta added.

Power management has been a focus at TI since the advent of Li-ion batteries and ubiquitous mobile electronics about two decades ago. “Our embedded processors continue to run more efficiently - consuming less energy while delivering greater processing capability - and our conversion technology makes sure that the power we use is efficiently transferred from the battery to the system in all operating conditions,” Sengupta said.

As an example, he mentioned TI’s MSP430 family of processors combined with its high-efficiency power conversion devices that incorporate a distributed control system such as the TPS62740. These components ensure almost all the battery’s energy is converted for useful work and not wasted. Furthermore, the enhanced accuracy of TI’s fuel gauge devices, including the bq27xxx family, allows end users to fully utilize the Li-ion cell’s capacity.

Next-generation battery technology

Sengupta said it is difficult to narrow down a single best choice for all applications as the “one size fits all” concept does not really work for mobile electronics.

“There are many innovations on all fronts and some will be well suited for new applications, but given the diversity of sizes, shapes and power requirements, there will probably be room for many new battery technologies,” he added. Take the case of Li/CFx, which boasts recent improvements resulting in increased maximum energy density.

This specific technology is not rechargeable, but does have an extended shelf life and good temperature stability. So, for some low-power, long-life span applications, it may be a better choice. However, there will still be a need for new forms, greater energy density and rechargeability for other applications.

“Due to the extensive testing and qualification required for new battery systems, historically, we have seen gradual evolution rather than radical changes over the years as far as high-volume production cells are concerned,” Sengupta said.

STMicroelectronics, which provides a range of ultralow-power chips such as microcontrollers, MEMs and power management ICs, is now engaged in the development of solid-state thin-film battery technology. The company is betting on low-capacity technologies, including the EnFilm.

“Our EnFilm battery can stay operational for 10 years with a number of charge/discharge cycles as high as 4,000,” said Igor Bimbaud, New Energies BU director at STMicroelectronics. “The form factor can also be customized.” The curved battery type is compliant with the IEC 10373 flexibility standard for smartcards. In the future, the maker plans to offer batteries that are much more flexible.

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