Flexible Lithium Ion Battery Breakthrough

Bendable batteries can be constructed from a new technique that uses Polymer-Assisted Metal Deposition to create current collectors.

Wearable electronics are finding new applications in healthcare monitoring, intelligent textiles, smartphones, Global Positioning System (GPS) tracking, and the Internet of Things (IoT). The problem has always been the bulk of the lithium ion battery needed to power such devices. Now, researchers at The Hong Kong Polytechnic University (PolyU) have developed a highly flexible, high-energy Textile Lithium Battery that offers more stable, durable and safe energy supply for wearable electronics. Their work is described in a university news release.

Polymer-Assisted Metal Deposition (PAMD) is used to deposit highly conductive copper (Cu) and nickel (Ni) onto pre-treated fabrics to act as flexible current collectors. (Image source: PolyU)

A Wearable Future

Professor Zheng Zijian, who leads the ITC research team, said in the news release, "Wearable technology has been named as the next global big market opportunity after smartphones. Global market revenues for wearable devices are forecasted to grow by leaps and bounds, of over 20% annually, to reach US$100 billion by 2024. As all wearable electronics will require wearable energy supply, our novel technology in fabricating Textile Lithium Battery offers promising solution to a wide array of next-generation applications, ranging from healthcare, infotainment, sports, aerospace, fashion, IoT to any sensing or tracking uses that may even exceed our imagination of today."   

The new technology applies PolyU's patented Polymer-Assisted Metal Deposition (PAMD), in which, “highly conductive metal, copper (Cu) and nickel (Ni) are uniformly and conformally deposited onto pre-treated fabrics.” According to PolyU, such fabricated metallic fabrics, featuring low sheet resistance and large surface area, serve as current collectors in battery. Active materials are added that act as cathode and anode, the metallic fabrics, together with separator and electrolyte, are assembled into the Textile Lithium Battery.

More Power, Excellent Flexibility

PolyU's novel lightweight Textile Lithium Battery reportedly demonstrates a high energy density of more than 450 Wh/L, and excellent flexibility — “with a bending radius of less than 1mm, and foldability of over 1,000 cycles with marginal capacity degradation,” according to the news release. By comparison, some existing bendable lithium batteries can only reach a bending radius of about 25 mm, and with an energy density of less than 200 Wh/L. The Textile Lithium Battery is less than 0.5 mm thick and also is capable of fast charging and discharging. PolyU claims it has a cycle life comparable with conventional lithium batteries, retaining 80% of its capacity after 500 charge and discharge cycles.

PolyU reports, “Laboratory tests conducted by the ITC team have proven the extremely high mechanical stability, durability and safety of the Textile Lithium Battery under deformation. When the battery is repeatedly folded in half, twisted at different angles or freely crumpled, its voltage window remained unchanged. Bending test showed that the battery can be bent over 1,000 times with marginal capacity degradation. Safety tests conducted by continuous hammering, trimming with scissors and penetrating with nail proved the battery can stably provide power output for the electronic components with no risk of catching fire or burst.”

Senior Editor Kevin Clemens has been writing about energy, automotive, and transportation topics for more than 30 years. He has masters degrees in Materials Engineering and Environmental Education and a doctorate degree in Mechanical Engineering, specializing in aerodynamics. He has set several world land speed records on electric motorcycles that he built in his workshop.

 

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