Pyrolytic Carbon Nanosheets for Ultrafast and Ultrastable Sodium‐Ion Storage

Abstract

Na-ion cointercalation in the graphite host structure in a glyme-based electrolyte represents a new possibility for using carbon-based materials (CMs) as anodes for Na-ion storage. However, local microstructures and nanoscale morphological features in CMs affect their electrochemical performances; they require intensive studies to achieve high levels of Na-ion storage performances. Here, pyrolytic carbon nanosheets (PCNs) composed of multitudinous graphitic nanocrystals are prepared from renewable bioresources by heating. In particular, PCN-2800 prepared by heating at 2800 °C has a distinctive sp carbon bonding nature, crystalline domain size of ≈44.2 Å, and high electrical conductivity of ≈320 S cm , presenting significantly high rate capability at 600 C (60 A g ) and stable cycling behaviors over 40 000 cycles as an anode for Na-ion storage. The results of this study show the unusual graphitization behaviors of a char-type carbon precursor and exceptionally high rate and cycling performances of the resulting graphitic material, PCN-2800, even surpassing those of supercapacitors.

High Capacity Adsorption—Dominated Potassium and Sodium Ion Storage in Activated Crumpled Graphene

“…The Na/Na + cycled A-CG electrode also well maintained its morphology and showed a similar integrated I G /I D ratio (0.66) to pristine A-CG, indicating the good structural stability for Na storage. As shown in Table S2, Supporting Information, [25,26,33,46,61,[84][85][86][87][88][89][90][91][92][93] the cyclability of the A-CG electrode versus Na/Na + is also highly favorable as compared to state-of-the-art sodium carbons.…”

Hierarchically Nanoporous 3D Assembly Composed of Functionalized Onion‐Like Graphitic Carbon Nanospheres for Anode‐Minimized Li Metal Batteries

“…The ordered graphitic structures were also confirmed by XRD with a very sharp graphite (002) peak at 26.0° 2θ (Figure 1g). [40] The sharp graphite (002) peak supports that the primary nanoparticles with several nanometers in diameter permanently agglomerated into a nanoporous secondary structure with high crystallinity. In addition, the presence of graphite (100) peak at 42° indicates in-plane ordering of the poly-hexagonal carbon structures, which is consistent with the results obtained from Raman spectrum.…”

“…The presence of the D and G band pair indicates poly-hexagonal carbon structures because the D and G bands originate from the disordered A 1g breathing mode and the E 2g vibration mode of six-membered ring structures, respectively. [39,40] From the sharp peak pair, an approximate lateral size of the ordered poly-hexagonal carbon structures (L a ) can be calculated by comparing the G to D intensity ratio (I G /I D ). The Raman spectrum of FO-GCNs showed an I G /I D value of ≈1.15, which corresponds to L a of ≈5 nm.…”

Engineering Surface Oxygenated Functionalities on Commercial Carbon toward Ultrafast Sodium Storage in Ether-Based Electrolytes

“…6 Initially, disordered carbon materials, which are structurally composed of the curved graphene layers with large interlayer spacings and the turbostratic nanodomains with desirable pores, could generate reversible capacities as high as 300 mAh g -1 but with relatively poor rate capabilities and cycle performances [18][19][20][21][22][23][24][25] . Inspired by lithium equivalents, the rational nanostructured design [26][27][28][29][30][31][32][33][34][35][36][37][38] and the appropriate heteroatom doping 34,[39][40][41][42][43][44][45][46][47][48][49][50] , were widely employed to develop carbonaceous materials with a highly reversible capacity and a long cycle life.…”