Secondary Bonding Channel Design Induces Intercalation Pseudocapacitance toward Ultrahigh‐Capacity and High‐Rate Organic Electrodes

Abstract

materials, which inevitably raises several significant problems in synthetic energy consumption, metal resource crisis, and environmental footprint. [2,3] Against this backdrop, organic materials have become significantly attractive owing to their unique merits of structural diversity, designability, low production cost, and minimum footprint in nature. [4][5][6][7] In the past decade, organic compounds with redox-active centers, including quinones, [8] carboxylates, [9] imines, [10] alkenes, [11] alkynes, [12] azo-, [13] organosulfur-, [7] and radical-groups, [2] have been intensively studied as potential anode/cathode materials for Li-ion batteries and other alkali cation-based batteries. [2,7] As battery researchers are moving in this new direction, it is of much importance to revisit organic electrode materials with a comprehensive perspective for addressing their practical roadblocks. Even though many promising organic electrode materials have been proposed by molecular design, most of them still suffer from low component utilization [14] and sluggish reaction kinetics. [15] It is intrinsically attributed to too localized active sites of charged atoms in specific functional groups such as CX and CXY (X, Y = O, N, S, P). [16] On one hand, the vast majority of organic electrode materials are based on redox chemistry at functional groups, while other components in Organic electrode materials have shown extraordinary promise for green and sustainable electrochemical energy storage devices, but usually suffer from low specific capacity and poor rate capability, which is largely caused by inactive components and diffusion-controlled Li + intercalation. Herein, high-rate Li + intercalation pseudocapacitance in organic molecular crystals is achieved through introducing weak secondary bonding channels, far exceeding their theoretical capacity based on redox chemistry at functional groups. The authors' combined experimentally electrochemical characterization with first-principles calculations show that the heterocyclic organic molecule 2,2′-bipyridine-4,4′-dicarboxylic acid (BPDCA) crystal permits a four-electron redox reaction at conventional CO and CN groups and a six-electron intercalation pseudocapacitance along conjugated alkene hydrogen bonding channels (H 2 NC 5 H⋯OC(OH)) and heterocyclic aromatic stacking channels (C 5 H 3 N⋯NH 3 C 5 ). The BPDCA electrode delivers an ultrahigh reversible capacity of 1206 mAh g -1 at 0.5 A g -1 and an exceptional rate capability. A 4.8 V high-energy/power-density BPDCA anode-based hybrid Li-ion capacitor is thus realized. This work opens a new avenue for developing organic intercalation pseudocapacitive materials via secondary bonding structure design.

A bifunctional electrolyte for activating Mg–Li hybrid batteries

“…It would therefore favor optimal electron dispersion and conduction in the framework. 39,40 This can also be confirmed by the corresponding M-L@POF bandgaps that decrease from 2.3 eV (Mg 2 C 13 N 8 H 5 ) and 0.9 eV (Mg 2 Li 1 C 13 N 8 H 5 ) to 0.2 eV (Mg 2 Li 6 C 13 N 8 H 5 ) with continued lithiation, according to the simulations (Fig. 3c).…”

Ion Flux Self-Regulation Strategy with a Volume-Responsive Separator for Lithium Metal Batteries

“…The transition metal oxide/porous polyolefin separator/graphite becomes the classical battery system based on subverting the lithium/MnO 2 battery system, which suffers from serious safety challenges caused by the dendrite lithium. Nowadays, with the rapid development of electric vehicles and grid energy storage, there are imperious demands in the high power and capacity density of the batteries. − Since several alternative cathode materials have achieved commercial application, the breakthrough of the high-capacity anode, to substitute the commercial graphite anode which only has a specific capacity of 340 mAh g –1 , determines the upper limit of the battery density. , Therefore, the research of lithium metal anode becomes the focus again with the development of new materials and technologies. , However, safety concerns caused by dendrite lithium growth as well as the volume change and thermal shock still restrict its conversion from the laboratory to the factory. − …”

Trinitroaromatic Salts as High-Energy-Density Organic Cathode Materials for Li-Ion Batteries

“…So, the discharge potential profile is predicted by inserting three Li ions twice at a time. Based on the previous studies, we tried some calculations by inserting Li along possible channels to explore the lowest energy reaction path . To obtain the optimum Li-ion distribution in these structures, the low-energy Li-ion occupancy structures were quickly filtered using Monte Carlo (MC) sampling electrostatic potential calculations implemented in the “supercell” software package .…”

“…Based on the previous studies, we tried some calculations by inserting Li along possible channels to explore the lowest energy reaction path. 44 To obtain the optimum Liion distribution in these structures, the low-energy Li-ion occupancy structures were quickly filtered using Monte Carlo (MC) sampling electrostatic potential calculations implemented in the "supercell" software package. 45 The resulting optimal structure is used as the initial structure for the DFT calculations.…”