Flexible Fiber-Shaped Lithium and Sodium-Ion Batteries with Exclusive Ion Transport Channels and Superior Pseudocapacitive Charge Storage
As fiber battery becomes momentous, the wearable energy market has devoted to developing them with better specific capacity, longer lifetime, and sufficient flexibility. However, the sluggish kinetics of ion transport in the electrochemical process has become a bottleneck for practical applications. Herein, we directly employ 2D tungstate and graphene nanosheets as building blocks to construct fiber electrodes with 2D nanofluidic channels and 3D interconnected tunnels for exclusive and fast ion transport. Such structures could accelerate the ionic transport process essentially, making the electrochemical process without limitations from solid-state diffusion and finally facilitating efficient pseudocapacitive charge storage. The resulting fiber-shaped lithium- and sodium-ion batteries manifest extremely high capacity (206 and 178 mAh g−1 for LIB and SIB, respectively), excellent rate performance, long-term cycling capability (1000 cycles), and outstanding flexibility (200 bending cycles) which could continuously light up the LED even under mechanical deformations. This work provides new insights into the structural engineering of fiber electrode, showing great promise for boosting battery performance to a new level in actual wearable applications.