Flexible batteries may be the next big thing in energy storage
As our daily gadgets and wearable electronics get increasingly thinner, lighter and flexible, regular lithium-ion batteries are beginning to show their limitations. They are rigid, heavy and bulky, making them ill-suited for next-gen devices. However, a new class of flexible batteries is emerging that could transform the technology landscape. Here's a closer look at some of the major developments in flexible battery research.
Thinner and more durable cell designs
Traditional battery materials like lithium cobalt oxide cathodes are too brittle to be integrated into flexible form factors. Researchers are experimenting with new nano-structured materials that can deliver the required energy and power while maintaining mechanical flexibility. Some notable efforts include developing freestanding graphene anodes and nanowire-based cathodes that are highly deformable, lightweight and durable over many charge-discharge cycles.
Stretchable solid electrolytes
The role of solid electrolytes in Flexible Batteries cannot be overstated. They must not only conduct ions swiftly but also withstand mechanical stresses during bending or stretching without damage. Scientists from MIT created a highly elastic solid electrolyte made of polyacrylate polymers interspersed with lithium salt. It demonstrated excellent ion conductivity even when stretched up to 300% of its initial length. Other groups developed polymer-borate and poly (ethylene oxide)-based electrolytes with self-healing properties.
Paper-thin battery prototypes
Leveraging advanced materials and thin film deposition processes, several proof-of-concept flexible battery prototypes under 100 microns in thickness have emerged. Researchers at the University of Illinois fabricated an ultra-thin, bendable lithium-ion battery only 20 microns thick using vapor deposition techniques. It could withstand over 1000 cycles of bending and delivered an energy density of 0.5 mAh/cm2. Scientists at Penn State University designed an elastic battery 50 microns thick using laser-scribed nanowire electrodes and enabled full functionality even after severe twisting and folding.
Stretchable power sources for wearables
Wearable devices integrated directly onto the skin or clothing require battery designs that can tolerate continual skin-like mechanical motions. Scientists developed bio-integrated transparent and self-charging batteries made of carbon nanotube fibers that can harvest energy from body movements and surrounding radio waves. Researchers at the University of Texas devised an elastic lithium-ion battery that maintained 88% of its original capacity after 1000 stretching cycles to 50% strain, making it viable for wearable electronics.
Novel manufacturing techniques
Mass production will be crucial for bringing flexible batteries to commercial reality. Researchers are exploring new types of roll-to-roll and inkjet printing techniques to customize battery designs and fabricate complete flexible energy storage systems. Ambri, a MIT spin-off company, is scaling up its novel Liquid Metal Battery technology which replaces rigid solid electrodes with lightweight encapsulated liquid metals. Ambri’s design is highly compatible with continuous roll-to-roll manufacturing processes. Further advancements in manufacturing promise to drive down costs significantly.
Commercial products on the horizon
Driven by explosive growth in the wearables sector, we may soon see the first flexible battery commercial products hit the market. Samsung, LG and Panasonic are among the electronics giants aggressively working on next-gen flexible battery prototypes tailored for foldable phones and smart glasses. Chinese company Enfucell has developed ultra-thin printable paper batteries and ink-based manufacturing suitable for integrating into clothing or packaging materials. Startups like Blue Spark Technologies and Ilika are also racing to launch flexible battery powered devices in portable electronics, healthcare and Internet of Things applications within the next two years.
In summary, flexible batteries hold immense potential to revolutionize industries across the board by powering a new class of ultra-portable, wearable and visually appealing smart devices. After years of intensive research, the technical barriers are slowly being overcome through cutting-edge material science and manufacturing technologies. With continued innovation and mass production developments, flexible batteries may reach commercial scale within this decade to fulfill the promise of truly limitless device form factors. The future indeed looks bright and flexible.
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