A half millimeter thick coplanar flexible battery with wireless recharging capability

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Conventional flexible lithium ion batteries (LIBs) use stacked cofacial cell configurations, limiting integration with thin electronic devices.
• This stacked design presents challenges for applications like smart cards and medical patches due to bulkiness and reduced flexibility.

Purpose of the Study:

• To develop a novel coplanar cell structure for flexible LIBs that overcomes the limitations of traditional stacked designs.
• To enhance bending tolerance, enable higher cell voltages, and reduce overall device thickness for improved integration.

Main Methods:

• Designed and fabricated LIBs with an interdigitated coplanar electrode structure on the same plane.
• Investigated the electrochemical performance, including voltage delivery and stability under repeated bending cycles.
• Evaluated the role of the pouch case as a protective barrier against dendrite growth and short circuits.

Main Results:

• Achieved a coplanar flexible LIB with a cell thickness below 0.5 mm and a voltage output of 7.4 V.
• Demonstrated stable electrochemical performance over 5000 bending cycles (5 mm bending radius).
• Confirmed the pouch case's effectiveness in preventing lithium dendrite growth and short circuits while maintaining thinness.

Conclusions:

• The coplanar electrode design offers significant advantages in flexibility, voltage enhancement, and thickness reduction for LIBs.
• The developed flexible LIB is suitable for integration into thin, wearable, and portable electronic devices.
• Demonstrated practical usability through integration with wireless charging and solar cells.