The solvent-guided shaping of conjugated polymides activates O/N Zn-storage sites on the robust carbon architecture, which facilitates reversible Zn electrosorption and durable charge tansfer toward high energy-power Zn-ion capacitors. 

<i>In situ</i> nanoarchitecturing of conjugated polyamide network-derived carbon cathodes toward high energy-power Zn-ion capacitors

The synergism of large surface area, multiscale porous structure, and good conductivity endows hierarchical carbon nanocages with high-level supercapacitive performances. Further nitrogen doping greatly improves the hydrophilicity, which boosts the supercapacitive performances to an ultrahigh specific capacitance of up to 313 F g(-1) at 1 A g(-1).

Hydrophilic hierarchical nitrogen-doped carbonnanocages for ultrahigh supercapacitive performance

Tailor‐made nanoarchitecturing of highly zincophilic and stable carbon scaffolds is critical but still challenging for Zn‐ion storage with double‐high supercapacitive activity and durability. Herein, a Lewis pair interaction‐guided self‐assembly strategy is reported to design carbon superstructures for activating Zn‐storage sites. The Lewis acid (ferric chloride) and base (p‐phenylenedimethanol) can interact to form organic nanoparticle modules that self‐assemble into well‐defined superstructures constructed from nanotentacle‐building blocks via hydrogen‐bonding and π−π stacking. As‐designed carbon superstructures as aqueous Zn‐ion capacitor cathodes empower the high accessibility of the build‐in zincophilic sites and efficient ion migration with low‐energy hurdles. A charge‐storage mechanism, i.e., opposite charge‐carrier uptake coupled with multielectron redox response, is proposed, which entails the alternate binding of Zn2+/CF3SO3− at active sites and the robust interactions between Zn2+ and electronegative carbonyl/pyridine motifs to form O−Zn−N bonds. This unique electrochemistry contributes to high‐rate survivability (100 A g−1), high‐energy density (161.2 Wh kg−1cathode), and ultralong lifespan (400 000 cycles), superior to state‐of‐the‐art Zn‐ion devices in comprehensive performances. This study sheds light on structural engineering for carbon‐based materials toward advanced energy storage.

Lewis Pair Interaction Self‐Assembly of Carbon Superstructures Harvesting High‐Energy and Ultralong‐Life Zinc‐Ion Storage

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.

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

A solvent–precursor interaction-guided synthetic strategy is proposed to design heteroatomic carbon cathodes with customized microstructures towards efficient Zn-ion energy storage. 

Unraveling the role of solvent–precursor interaction in fabricating heteroatomic carbon cathode for high-energy-density Zn-ion storage

High-energy aqueous supercapacitors enabled by N/O codoped carbon nanosheets and “water-in-salt” electrolyte

Highly active and stable cathodes are critical for aqueous Zn–organic batteries with high capacity, fast redox kinetics, and long life. We herein report para-, meta-, and ortho-dinitrobenzene (p-, m-, and o-DB) containing two successive two-electron processes, as cathode materials to boost the battery performance. Theoretical and experimental studies reveal that nitro constitutional isomerism is key to zincophilic activity and redox kinetics. p-DB hosted in carbon nanoflower harvests a high capacity of 402 mAh g−1 and a superior stability up to 25 000 cycles at 5 A g−1, giving a Zn–organic battery with a high energy density of 230 Wh kg−1. An anionic co-insertion charge storage mechanism is proposed, entailing a two-step (de)coordination of Zn(CF3SO3)+ with nitro oxygen. Besides, dinitrobenzene can be electrochemically optimized by side group regulation via implanting electron-withdrawing motifs. This work opens a new window to design multielectron nitroaromatics for Zn–organic batteries. 

Cody W. Thompson

Papers

<i>In situ</i> nanoarchitecturing of conjugated polyamide network-derived carbon cathodes toward high energy-power Zn-ion capacitors

High-energy aqueous supercapacitors enabled by N/O codoped carbon nanosheets and “water-in-salt” electrolyte

High-energy aqueous supercapacitors enabled by N/O codoped carbon nanosheets and “water-in-salt” electrolyte

Anionic Co‐insertion Charge Storage in Dinitrobenzene Cathodes for High‐Performance Aqueous Zinc–Organic Batteries