Designing Heterodiatomic Carbon Hydrangea Superstructures via Machine Learning-Regulated Solvent-Precursor Interactions for Superior Zinc Storage.

Carbon superstructures with exquisite morphologies and functionalities show appealing prospects in energy realms, but the systematic tailoring of their microstructures remains a perplexing topic. Here, hydrangea-shaped heterodiatomic carbon superstructures (CHS) are designed using a solution phase manufacturing route, wherein machine learning workflow is applied to screen precursor-matched solvent for optimizing solvent-precursor interaction. Based on the established solubility parameter model and molecular growth kinetics simulation, ethanol as the optimal solvent stimulates thermodynamic solubilization and growth of polymeric intermediates to evoke CHS. Featured with surface-active motifs and consecutive charge transfer paths, CHS allows high accessibility of zincophilic sites and fast ion migration with low energy barriers. A anion-cation hybrid charge storage mechanism of CHS cathode is disclosed, which entails physical alternate uptake of Zn2+/CF3SO3 - ions at electroactive sites and chemical bipedal redox of Zn2+ ions with carbonyl/pyridine motifs. Such a beneficial electrochemistry contributes to all-round improvement in Zn-ion storage, involving excellent capacities (231 mAh g-1 at 0.5 A g-1; 132 mAh g-1 at 50 A g-1), high energy density (152 Wh kg-1), and long-lasting cyclability (100 000 cycles). This work expands the design versatilities of superstructure materials and will accelerate experimental procedures during carbon manufacturing through machine learning in the future.

Hydrogen-bonded micelle assembly directed conjugated microporous polymers for nanospherical carbon frameworks towards dual-ion capacitors.

Well-orchestrated carbon nanostructure with superb stable framework and high surface accessibility is crucial for zinc-ion hybrid capacitors (ZIHCs). Herein, a hydrogen-bonded micelle self-assembly strategy is proposed for morphology-controllable synthesis of conjugated microporous polymers (CMPs) derived carbon to boost zinc ion storage capability. In the strategy, F127 micellar assembly through intermolecular hydrogen bonds serves as structure-directed agents, directing CMPs' oligomers grow into nanospherical assembly. The nanospherical carbon frameworks derived from CMPs (CNS-2) have shown maximized surface accessibility due to their plentiful tunable porosity and hierarchical porous structure with abundant mesoporous interconnected channels, and superb stability originating from CMPs' robust framework, thus the CNS-2-based ZIHCs exhibit ultrahigh energy density of 163 Wh kg-1 and ultralong lifespan with 93 % capacity retention after 200, 000 cycles at 20 A g-1. Charged ion storage efficiency also lies in dual-ion alternate uptake of Zn2+ and CF3SO3- as well as chemical redox of Zn2+ with carbonyl/pyridine motifs forming O-Zn-N bonds. Maximized surface accessibility and dual-ion storage mechanism ensure excellent electrochemical performance. Thus, the hydrogen-bond-guide micelle self-assembly strategy has provided a facile way to design nanoarchitectures of CMPs derived carbon for advanced cathodes of ZIHCs.

π-Conjugated molecule mediated self-doped hierarchical porous carbons via self-stacking interaction for high-energy and ultra-stable zinc-ion hybrid capacitors.

Understanding the self-stacking interactions in precursors can facilitate the preparation of high-performance carbon materials and promote the commercial application of zinc ion hybrid capacitors (ZIHCs). Here, a π-conjugated molecule mediated pyrolysis strategy is presented to prepare carbon materials. Taking intermolecular force simulation (reduced density gradient plots) as a guide, the relationship between the self-stacking interactions in π-conjugated molecules and the structural parameters of carbon materials can be extrapolated. The resultant self-doped hierarchical porous carbons (NHPCs) derived from 1, 8, 4, 5-naphthalenetetracarboxdiimide with suitable self-stacking interactions empower the highest specific surface areas (2038 m2/g) and surface opening macropores. The NHPCs-based ZIHCs deliver a high capacity of 220 mAh/g, a high energy density of 149.5 Wh kg-1 and a super-stable cycle lifespan with 93.2 % capacity retention after 200, 000 cycles. The excellent electrochemical performance roots in the superior hierarchical porous structure with surface opening macropores, which guarantees the structural stability of carbon cathodes upon repeated rounds. Meanwhile, the heteroatom doping further relieves the kinetics concern of Zn2+ uptake/removal to enhance O-Zn-N binding particularly at high discharge currents. Besides, the proton-assisted Zn2+ dual-ion storage mechanism plays an essential role in the energy storage process. This work demonstrates a facile synthesis method and advances the fundamental understanding of its dual-ion storage mechanism.

Spatial Confinement Strategy for Micelle-Size-Mediated Modulation of Mesopores in Hierarchical Porous Carbon Nanosheets with an Efficient Capacitive Response.

Commercial supercapacitors using available carbon products have long been criticized for the under-utilization of their prominent specific surface area (SSA). In terms of carbonaceous electrode optimization, excessive improvement in SSA observed in the gaseous atmosphere might have little effect on the final performance because cracked/inaccessible pore alleys considerably block the direct electrolyte ion transport in a practical electrochemical environment. Herein, mesopore-adjustable hierarchically porous carbon nanosheets are fabricated based on a micelle-size-mediated spatial confinement strategy. In this strategy, hydrophobic trimethylbenzene in different volumes of the solvent can mediate the interfacial assembly with a carbon precursor and porogen segment through π-π bonding and van der Waals interaction to yield micelles with good dispersity and the diameter varying from 119 to 30 nm. With an increasing solvent volume, the corresponding diffusion coefficient (3.1-14.3 m2 s-1) of as-obtained smaller micelles increases, which makes adjacent micelles gather rapidly and then grow along the radial direction of oligomer aggregates to eventually form mesopores on hierarchically porous carbon nanosheets (MNC150-4.5). Thanks to the pore-expansion effect of trimethylbenzene, the mesoporous volume can be adjusted from 28.8 to 40.0%. Mesopores on hierarchically porous carbon nanosheets endow MNC150-4.5 with an enhanced electrochemically active surface area of 819.5 m2 g-1, which gives rise to quick electrolyte accessibility and a correspondingly immediate capacitive response of 338 F g-1 at 0.5 A g-1 in a three-electrode system. Electrolyte transport through pathways within MNC150-4.5 ultimately enables the symmetric cell to deliver a high energy output of 50.4 Wh kg-1 at 625 W kg-1 in a 14 m LiOTF electrolyte and 95% capacitance retention after 100,000 cycles, which show its superior electrochemical performance over representative carbon-based supercapacitors with aqueous electrolytes in recent literature.

Sulfanilic Acid Pending on a Graphene Scaffold: Novel, Efficient Synthesis and Much Enhanced Polymer Solar Cell Efficiency and Stability Using It as a Hole Extraction Layer.

In this contribution, we describe a novel, facile, and scalable methodology for high degree functionalization toward graphene by the reaction between bulk graphite fluoride and in situ generated amine anion. Using this, the rationally designed sulfanilic acid pending on a graphene scaffold (G-SO3H), a two-dimensional (2D) π-conjugated counterpart of poly(styrenesulfonate), is available. Combined reliable characterizations demonstrate that a very large quantity of sulfanilic blocks are linked to graphene through the foreseen substitution of carbon-fluorine units and an unexpected reductive defluorination simultaneously proceeds during the one-step reaction, endowing the resultant G-SO3H with splendid dispersity in various solvents and film-forming property via the former, and with recovered 2D π-conjugation via the latter. Besides, the work function of G-SO3H lies at -4.8 eV, well matched with the P3HT donor. Awarded with these fantastic merits, G-SO3H behaves capable in hole collection and transport, indicated by the enhanced device efficiency and stability of polymer solar cells (PSCs) based on intensively studied P3HT:PCBM blends as an active layer. In particular, comparison with conventional poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonate) and recently rising and shining graphene oxide, G-SO3H outperforms above 17 and 24%, respectively, in efficiency. More impressively, when these three unencapsulated devices are placed in a N2-filled glovebox at around 25 °C for 7 weeks, or subject to thermal treatment at 150 °C for 6 h also in N2 atmosphere, or even rudely exposed to indoor air, G-SO3H-based PSCs exhibit the best stability. These findings enable G-SO3H to be a strongly competitive alternative of the existing hole extraction materials for PSC real-life applications.