A Rigid Naphthalenediimide Triangle for Organic Rechargeable Lithium‐Ion Batteries

Abstract

materials for lithium-ion batteries. [19][20][21] Despite the ease of their synthesis and the ability to tune their electronic properties, the neutral states of organic small molecules are often quite soluble in common battery electrolyte solvents, such as carbonates and ethers, resulting in fast capacity decay during cycling tests. [22][23][24][25][26][27][28] Polymerization of redox-active units minimizes their solubility, but usually requires the use of large amounts of electron-conducting additive-e.g., carbon black, graphene, or carbon nanotubes-to provide a continuous electronic pathway between the redox-active sites and the electrodes. [29][30][31] Most importantly, the measured rate capabilities of organic electrodes tend to be much lower than those of traditional inorganic ones, perhaps because they lack a rigid 3D nanoporous framework-a feature inherent to crystalline inorganic materials-to aid and abet the effi cient diffusion of Li + ions throughout the active layer to sustain the effectiveness of electrochemical reactions in the battery. [32][33][34] Recently, we reported [ 35 ] the preparation of the molecular triangular prism (−)-NDI-᭝ ( Figure 1 A) and its enantiomer (+)-NDI-᭝ from a single-step condensation of commercially available naphthalene dianhydride with ( RR )-and ( SS ) -trans -1,2-diaminocyclohexane, respectively. These thermally stable compounds ( Figure S1, Supporting Information) contain three redox-active naphthalenediimide (NDI) units in a rigid, cyclic constitution. Solution-state studies, together with DFT calculations, reveal through-space electron delocalization across the overlapping π-orbitals of the three NDI units as a consequence of their triangular constitution. As a result of this stable electronic coupling, a single molecule of (−)-or (+)-NDI-᭝ can store and release up to six electrons reversibly, yielding a theoretical capacity of 154.8 mAh g −1 . Furthermore, the (−)-and (+)-NDI-᭝ molecular triangles are only sparingly soluble in nonaqueous electrolyte solvents, leading us to believe that they would be highly attractive candidates to act as active materials for use in organic rechargeable lithium-ion batteries. In order to understand the structure-performance relationship of these triangles, we also prepared a monomeric NDI derivative NDI-Ref (Figure 1 B) as a control compound.We began our investigation by evaluating the performance of (−)-NDI -᭝ versus NDI-Ref as the active component within organic electrodes. Electrode slurries of each were prepared by mixing the desired active material with conductive carbon black and 10 wt% of polyvinylidene fl uoride (PVDF) binder in anhydrous N -methyl-2-pyrrolidone (NMP). From screening various organic electrode compositions (see the Supporting Information), we found that 50 wt% of (−)-NDI -᭝ active material was the highest content loading we could achieve that still Batteries, one of the most effi cient and convenient energy storage technologies, have powered a revolution in our daily lives for over a century now. The explorat...

Molecular Engineering with Organic Carbonyl Electrode Materials for Advanced Stationary and Redox Flow Rechargeable Batteries

“…[115] To prove their assumption, a carboxylic acid-containing . [116] www.advmat.de www.advancedsciencenews.com perylenediimide species (benzoic-PDI) was designed as a model organic cathode. a) Introducing heteroaromatic moieties, [104] b) Expanding the π-aromatic conjugation [112] and c) design of rigid 3D-porous carbonyls and structural formulas and reaction mechanism of (−)-NDI-Δ.…”

“…[116] As displayed in Figure 7c, the prepared (−)-NDI-Δ was derived from the active units of naphthalene diimide, forming rigid and cyclic structures. [116] As displayed in Figure 7c, the prepared (−)-NDI-Δ was derived from the active units of naphthalene diimide, forming rigid and cyclic structures.…”

Redox-Active Macrocycles for Organic Rechargeable Batteries

“…12, 13, 14 Despite the long history 10 of macrocyclic chemistry, direct observation of its impact on performance of energy storage devices, such as batteries and supercapacitors, has limited precedent. 14,15 Herein, we demonstrate that constraining three redox-active units exhibiting multiple discrete potentials-and thus giving rise to two-plateau voltage profiles in batteries-into a rigid triangular macrocycle has allowed us to access cathode materials which exhibit single well-defined voltage profiles. Our investigation suggests that the intrinsic properties of the redox unit itself and the mutual arrangement of individual redox units within the active material are equally critical to designing organic electrodes for rechargeable batteries.…”

A Microporous Covalent–Organic Framework with Abundant Accessible Carbonyl Groups for Lithium‐Ion Batteries

“…[5,6] This usually incurs agglomeration of polymer chains,a nd results in poor access of redoxactive groups by Li + or electrons,w hich are essential for electrochemical reactions,and hence low utilization efficiency of less than 70 %ofthe polymers,e specially at high rates. [9][10][11] Structuring microporous polymer framework electrodes with both facile Li + diffusion and electron transport is of crucial importance for organic LIBs. [9][10][11] Structuring microporous polymer framework electrodes with both facile Li + diffusion and electron transport is of crucial importance for organic LIBs.…”