Failure mechanism in fiber-shaped electrodes for lithium-ion batteries

Fiber-shaped lithium-ion batteries (LIBs) have attracted much attention since the birth of wearable electronics. Although these fiber-shaped LIBs are expected to be flexible, they still suffer from failure under bending during use, and no studies are available to understand the failure behavior and mechanism yet. Herein, fiber-shaped LIBs were fabricated by coating Si onto aligned carbon nanotube fibers. The failure behavior has been explored using electrochemical impedance spectroscopy and scanning electron microscopy. The main failure mechanism was then demonstrated as the loss of contact between the current collector/conductive network and active material, which was indicated by the interphase electrical contact resistance in the Nyquist plot. This study provides important clues in developing high-performance fiber-shaped LIBs by suppressing mechanical failure.