Light-Weight and Flexible Carbon Nanotubes (CNT) Tissues As Anode Materials for Flexible Li-Ion Microbatteries
Authors: Sugiawati Vinsensia Ade , Vacandio Florence , Ein-Eli Yair , Djenizian Thierry 
Published: February 2020

Currently, flexible power sources are gaining immense interests due to their potential applications in the next-generation flexible and wearable electronics, such as implantable medical devices, smart cards, electronic skin, sensors, RFID tags, and more [1]. As an allotrope of graphite, flexible carbon nanotubes (CNT) tissues are also capable of accommodating Li-ions as well as exhibits significantly higher reversible charge-discharge capacity compared to the commercial graphite (372 mAh/g). Due to its remarkable properties such as excellent flexibility, outstanding electrical properties, strong mechanical strength, high chemical stability and high reversible capacity, CNT tissues have been considered as competitive anode materials for flexible microbatteries [2]. Despite the CNT tissues showed outstanding properties as flexible anode materials, there is a major challenge needs to be tackled. Their immense surface area would significantly promote a high capacity loss in the first initial cycles [3]. As a consequence, the CNT electrode has a low Initial Coulombic Efficiency (ICE) due to a Solid Electrolyte Interphase (SEI) film formation upon initial lithiation. This SEI film consumes a large amount of Li ions in the first lithiation which then limits the cycling performance of the cells, particularly when pairing the CNT tissue anode with the cathode material in full-cell system.
In this work, a direct pre-lithiation is implemented to suppress the high irreversible capacity of the both pristine and polymer-coated CNT tissues [4]. Interestingly, the results show the high irreversible capacity can be significantly reduced after pre-lithiation. As shown in Figure 1, the polymer-coated CNT tissues deliver higher reversible capacity of 508 mAh/g (187 µAh/cm2) than that obtained for the pristine CNT (356 mAh g-1,131 μAh cm-2) at 10C rate over 500 cycles. Additionally, the polymer-coated CNT tissues deliver an excellent rate capabilities at high C-rate, 385 mAh/g (142 µAh/cm2) at 30C. In this communication, we will discuss the electrochemical deposition of polymer electrolyte into CNT tissues and the influence of direct pre-lithiation method at various pre-lithiation time on the electrochemical performances of the CNT electrodes.

References

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Figure 1