Biomass-Derived Ternary-Doped Porous Carbon Electrodes for Li-Ion Capacitors: Rational Preparation and Energy-Storage Mechanism Study

Abstract

Owing to the hybrid energy-storage features, Li-ion capacitors (LICs) inherit appealing properties from secondary batteries and supercapacitors, including high power density, high energy density and good cycling stability. However, incompatible kinetics between anode and cathode limit the performance improvement of the LICs. Moreover, the energy-storage mechanisms of carbon electrodes for LICs need to be further explored. Herein, we have prepared two ginkgo leaf-derived porous carbons (GLPCs) and used them as LIC electrodes. As resourceful biomass materials, ginkgo leaves have numerous O,N,S-enriched organics (e.g., flavonoids, alkaloids and thiophenes). By direct pyrolysis of the ginkgo leaves, ternary doped GLPCs are obtained without using additional dopants. The porosities, heteroatoms and defects for the GLPCs are tailored based on electrode requirements. The GLPCs obtained at 600 and 900 °C are specifically employed as the anode and cathode materials for LICs, respectively. The GLPC electrodes show good performance in half cells and their energy-storage mechanisms are interpreted by detailed ex situ and in situ experiments. DFT calculation results reveal that only specific heteroatom doping can enhance Li+ and PF6 − storage. Because of compatible electrode kinetics, the assembled LIC using the GLPC electrodes delivers high energy (118 Wh kg−1), high power (31.6 kW kg−1) and long lifespan.

An interface-enhanced continuous 2D-carbon network enabling high-performance Si anodes for Li-ion batteries

“…The high recovery of the D band and G band implies that the continuous carbon network of Si@GCNS could maintain dynamic structural stability during the cycling, which is also indirect evidence of stabilizing the Si structure. 45 The intensity change of the Si peak for the Si@GCNS anode further confirms the deduction. In the lithiation process, the spectral intensity of the Si characteristic peak gradually weakened when the voltage decreased.…”

Inorganic Skeleton Reinforcement—A Generic Approach to Improve the Mechanical Properties of Biochar

“…The Dband vibration originates from defects and disorder structures in carbon, while the G-band comes from the vibration of sp 2 hybrid carbon in the microcrystalline structure. Accordingly, the D-band is related to the degree of crystal defects, while the G-band represents the microcrystalline structure, and the degree of defect and graphitization can be evaluated by the ratio of the D-band to G-band (I D /I G ) [43][44][45][46]. After modification with TEOS, the I D /I G ratios of GL-TEOS-x (ratios of x = 0.5, 1, 1.5, 2, and 2.5 assigned to 1.08, 1.18, 1.31, 1.20, and 1.25, respectively) are greater than that of pristine GL (0.8), and the maximum value of I D /I G (1.31) can be obtained when the amount of TEOS is 1.5 mL.…”