Surface controlled pseudo-capacitive reactions enabling ultra-fast charging and long-life organic lithium ion batteries†
To develop ultra-fast charging and long-life lithium ion batteries, a surface-controlled pseudo-capacitive reaction mechanism for high-performance organic lithium ion batteries is developed based on a coaxial nanocomposite of an active anthraquinone-based covalent organic framework (AQ-COF) and carbon nanotubes. AQ-COF was grown on the surface of carbon nanotubes (AQ-COF@CNTs) through in situ polymerization to improve the conductivity and to facilitate electrochemical properties. AQ-COF grown on CNTs exhibited excellent rate performance and was found to retain 76% of its initial capacity at a current density of 5000 mA g−1 (33C), and even retained 48% at an ultra-high current density of 10 000 mA g−1 (66.7C). Furthermore, under long term cycling performance investigations, the AQ-COF@CNT based cathode retained 100% of its initial capacity even after 3000 charge–discharge cycles. We further evaluated the charge storage mechanism and found that pseudocapacitance arising from surface-controlled redox reactions, coupled with excellent charge-transfer properties owing to the conductive CNT network and facilitated by the large surface area of active material, is mainly responsible for this excellent rate and cycling performance.