Facile Synthesis of Graphene with Fast Ion/Electron Channels for High-Performance Symmetric Lithium-Ion Capacitors

Abstract

With the battery-type anode and capacitor-type cathode, lithium-ion capacitors (LICs) are expected to exhibit both high energy and high power density but suffer from the mismatch of the electrode reaction kinetics and capacity. Herein, to alleviate the mismatch between the two electrodes and synergistically enhance the energy/power density, we design a method of microwave irradiation reduction to prepare graphene-based electrode material (MRPG/CNT) with fast ion/electron pathway. The threedimensional structure of CNT intercalation to graphene inhibits the restacking of graphene sheets and improves the conductivity of the electrode material, resulting a rapid ion and electron diffusion channel. Due to its specific properties, MRPG/CNT materials can be used as both anode and cathode electrodes of LICs at the same time. As anode, MRPG/CNT shows a high capacity of 1200 mAh g −1 as well as high rate performance. As cathode, MRPG/CNT displays a high capacity of 108 mAh g −1 and the capacity retention of 100% after 8000 cycles. Coupling the prelithiated MRPG/CNT anode with MRPG/CNT cathode gives a full-graphene-based symmetric LIC, which achieves a high energy density of 232.6 Wh kg −1 at 226.0 W kg −1 , 111.2 Wh kg −1 at the ultrahigh power density of 45.2 kW kg −1 , and superior capacity retention of 86% after 5000 cycles. The structure design of this electrode provides a new strategy for alleviating the mismatch of LIC electrodes and constructing high-performance symmetrical LICs.

Super-strong CNT composite yarn with tight CNT packing via a compress-stretch process

“…CNT yarn is a one-dimensional, high bulk CNT assembly composed of CNT bundles and threads with a porous and hierarchical structure. Due to the excellent strength (∼100 GPa), large elastic modulus (∼1 TPa), and high conductivity (2 × 10 7 S m −1 ) of CNTs, the macro-scale CNT assemblies of a CNT yarn attracts tremendous attention, such as in wearable electronic textiles, 1–3 advanced materials, 4 energy storage, 5,6 nanotechnology. 7,8 In the past, various promising post-treatment methods have been used to improve the mechanical and electrical properties of CNT yarn.…”

Explosion Strategy Engineering Oxygen-Functionalized Groups and Enlarged Interlayer Spacing of the Carbon Anode for Enhanced Lithium Storage

“…The electrochemical performances of the assembled LIC device were measured, as illustrated in Figure . In order to obtain the matched kinetics, it is necessary to optimize the mass ratio of anode and cathode. , When the mass ratio of Ca-LSCM anode and YP-80F cathode is 1:6, the assembled Ca-LSCM//YP-80F LIC achieves the optimal performance (Figure a). Among all assembled LIC devices (Figure S22–24), the CV curves of optimal Ca-LSCM//YP-80F LIC at different scan rates exhibit a quasi-rectangular shape (Figure b), which is ascribed to the hybrid energy storage mechanisms of the anode and cathode.…”

“…The long-term cycling performance for LIC was tested on the NEWARE system. The energy and power densities of LIC were calculated by numerically integrating the galvanostatic discharge curves using eqs and : ,− E = prefixtrue∫ t 1 t 2 U I m normald t P = E t where m (g) represents the total mass of active materials in the anode and cathode, U (V) and I (A) represent the discharge current and operating voltage, respectively, and t (s) are the initial time of the discharge process ( t 1 ) and terminal time of the discharge process ( t 2 ).…”

Phosphorus and Nitrogen Codoped Carbon Nanoparticles as Both Anode and Cathode Materials with Enhanced Li+/PF6– Storage for High Energy Density Lithium-Ion Capacitors

“…To investigate the kinetic effect of P-doping on the Li + intercalation/deintercalation process, the galvanostatic intermittent titration technique (GITT) was used to evaluate the diffusion coefficient of Li + in the bulk phase of the electrode material during charging and discharging (details are explained in Supporting Information Figure S17). 40 Figures 3e and S18 show that the 8-PNC anode has a higher Li + diffusion coefficient of approximately 10 −8 to 10 −10 cm 2 s −1 compared to 8-NC (10 −9 to 10 −12 cm 2 s −1 ), 6-PNC (10 −9 to 10 −11 cm 2 s −1 ), and 4-PNC (10 −9 to 10 −11 cm 2 s −1 ) anodes, demonstrating the faster electrode process based on Li + intercalation/deintercalation mechanism in the 8-PNC anode. The favorable kinetic properties of the 8-PNC anode indicate that the increased interlayer spacing of the graphitized carbon microstructure by abundant P-doping effectively reduces the barrier of Li + diffusion in the interlayers.…”