Biomass-Derived Graphitic Carbon/Co₃O₄ Nanocomposites with Pseudocapacitance for Lithium Storage

Abstract

The reuse of waste biomass resources has recently become one of the most popular themes in the sustainable development of human society. To this end, waste scallion root was used as a biotemplate and carbon source to synthesize graphitic carbon-doped mesoporous Co3O4 nanocomposites (Co3O4/C) through a simple cobalt salt impregnation, carbonization, and low-temperature oxidation method. The effect of different carbon contents on the nanostructure and electrochemical performance is investigated. The hierarchical microtubes with a ribs-shaped inner wall in the product oxidized at 320 °C (Co3O4/C-2) are formed by the cross-linking of uniform small Co3O4 nanoparticles and 39.9% biomass-derived carbon. The Co3O4/C-2 nanocomposite has a large specific surface area of 360.2 m2·g–1, uniform mesopore size of 2.35 nm, and abundant oxygen vacancy defects. Such a unique nanostructure can exhibit a good pseudocapacitance behavior during the charge/discharge process, thereby effectively enhancing the lithium storage performance. The Co3O4/C-2 nanocomposite exhibits a high capacity and good rate capability. Even at 1.0 A g–1, it can still retain a capacity of 620 mA h g–1 after 1500 cycles. The superior capacity retention and long-cycling stability can be assigned to the synergistic effect of the unique nanostructure of the Co3O4/C-2 material (a uniform mesopore and large specific surface area), appropriate graphitic carbon doping, and pseudocapacitance contribution. Therefore, the reuse strategy of the waste scallion root biomass resource conforms to the concept of sustainable development and also provides a useful reference for the synthesis of other nanostructured anode materials with excellent performance.

Self-Standing Ti3C2Tx/MoO3–x Composite Films with High Volumetric and Gravimetric Capacitance Performances for Flexible Solid-State Supercapacitors

“…The redox peak current ( i ) and the relevant scanning rate ( v ) in the CV curves of Figure d follow an empirical power law relationship (eqs and ). in which a denotes the scaling factor and b is decided by the slope of log ( i ) and log ( v ) . We know that for a diffusion-controlled procedure, b is about 0.5, while for a surface capacitance-predominated procedure, b is about 1.0. − As presented in Figure e, the calculated b -values for the oxidation and reduction peaks in Ti 3 C 2 T x /MoO 3– x -50% are 0.61 and 0.50, respectively, indicating Faraday diffusion control as the dominant behavior in the sample. , Simultaneously, the b -values of the oxidized fraction and reduced fraction are calculated for specific potentials based on the CV potential window, which are both around 0.62 (as shown in Figure S4), similar to the above results. In order to further quantify the surface capacitance and diffusion contribution of the total capacitance, the following eqs and are used. in which k 1 v and k 2 v 1/2 denote the currents from the surface capacitance contribution and diffusive contribution, separately.…”

SnO2 Anchored in S and N Co-Doped Carbon as the Anode for Long-Life Lithium-Ion Batteries

“…Two broad peaks centering at 1364 and 1555 cm −1 can be observed, which can be ascribed to the lattice defect of carbon (D band) and the in-plane stretching vibrations of C sp 2 hybridization (G band). The value of I D /I G for the as-prepared three samples are determined to be 0.92, 0.92 and 0.93, illustrating the high graphitization degree for the 3 SnO 2 @SNC samples [1,30]. To determine the carbon contents for the three SnO 2 @SNC samples, thermogravimetric analysis (TGA) was employed (Figure 1d).…”

“…Lithium-ion batteries (LIBs) have been the focus of attention nowadays because of their advantages, such as their long lifetime, no memory effect, high energy density and their light weight [1][2][3][4]. However, the low theoretical value (372 mAh g −1 ) as well as poor cycling performance of graphite cannot meet the ever increasing requirement nowadays, especially in the fields of electrical vehicles [5][6][7].…”

Mesoporous Tubes Composed of Graphitic Carbon-Doped Co3O4 Nanoparticles for Lithium Storage

“…8 Large specific surface areas could strengthen the contact of electrode material with the electrolyte to easily form a stable solid electrolyte interface (SEI) film and supply more active sites for surface redox reactions. 7 Therefore, it can be inferred that the Co electrodes can be interpreted as the intercalation/deintercalation reaction of Li + ions in the GC layer, 30 electrodes display voltage platforms at 1.08 and 1.11 V, while the discharge platforms for the subsequent four cycles shift to near 1.34 and 1.32 V. In comparison, the charge platforms in the first cycles of the two electrodes are basically stable at about 2.0 V, while the charge platforms for the next four cycles shift to near 2.04 and 2.06 V. The reasons for such small differenced in voltage platform values are similar to those for CV curves. 40−42 The first discharge/charge-specific capacities of Co 3 O 4 /GC 350 and Co 3 O 4 /GC 450 are 1036.7/704.3 and 1201.2/864.1 mA h g −1 with Coulombic efficiencies of 67.9 and 71.9%, respectively.…”

“…This result demonstrates that the cheap biomassderived carbon-encapsulated strategy can well improve the electrochemical properties of Co 3 O 4 -based anodes. 30 Since abundant and renewable wood (such as poplar) has a hierarchically porous tube structure, it would be a good and inexpensive biotemplate for preparing advanced functional materials with hierarchical structures. 31,32 Our group just reported poplar branch (PB)-templated Co 3 O 4 microtubes that retained a capacity of 555.7 mA h g −1 after 1000 cycles at 1 A g −1 , demonstrating the feasible biotemplate method for preparing anode material with enhanced electrochemical performance.…”