Effect of Structural Ordering on the Charge Storage Mechanism of p-Type Organic Electrode Materials

Abstract

Understanding the properties that govern the kinetics of charge storage will enable informed design strategies and improve the rate performance of future battery materials. Herein, we study the effects of structural ordering in organic electrode materials on their charge storage mechanisms. A redox active unit, N,N′-diphenyl-phenazine, was incorporated into three materials which exhibited varying degrees of ordering. From cyclic voltammetry analysis, the crystalline small molecule exhibited diffusion-limited behavior, likely arising from structural rearrangements that occur during charge/discharge. Conversely, a branched polymer network displayed surface-controlled kinetics, attributed to the amorphous structure which enabled fast ionic transport throughout charge/discharge, unimpeded by sluggish structural rearrangements. These results suggest a method for designing new materials for battery electrodes with battery-like energy densities and pseudocapacitor-like rate capabilities.

Investigation of Ion-Electrode Interactions of Linear Polyimides and Alkali Metal Ions for Next Generation Alternative-Ion Batteries

“…Previous studies have demonstrated that the kinetics of organic battery systems are heavily influenced by the bulk structure of the redox-active material. 56,57 Further, based on our findings…”

“…In addition to readily accommodating different charge-compensating ions, the flexible, spacious natures of redoxactive polymers are known to accommodate ions with either no solvent molecules, a partial solvation shell, or even a full solvation shell. 56,64,65 This contrasts with metal oxide electrode materials which require the charge-compensating ion to shed its solvent shell at the electrode-electrolyte interface prior to intercalation into the tightly packed lattice. 66 The differences in performance as a function of ion in the three PDI-based polymers likely arise due to different phenomena associated with accommodating these ions within the polymer structures.…”

Quinone-Based Conducting Three-Dimensional Metal–Organic Framework as a Cathode Material for Lithium-Ion Batteries

“…Organic redox-active materials have been extensively applied as electrode materials in rechargeable lithium-ion batteries (LIBs) for their abundant resources, low cost, and tunable molecular structures. − However, most traditional organic materials, such as carbonyl compounds − and radical polymers, − are plagued by their inherent characteristics of low electronic conductivity, which lead to sluggish electron/ion diffusion kinetics, insufficient utilization of active sites, and inferior electrochemical performance at high current density. Introduction of conductive carbon is an effective strategy, for instance, 50–80% conductive species are required for radical polymers to reduce the polarization and improve the rate performance. − Unfortunately, the large amount of inactive species decreases the specific capacities of the batteries.…”

Polymer Electrode Materials for Lithium‐Ion Batteries

“…As a result, the p-DPPZ delivered higher capacity retention of 81.7% after 1000 cycles (Figure 21e). [201][202][203] In addition, the 1-/2-positions of phenazine and phenyl units are usually modified with different functionalities to adjust the redox voltage. The redox plateaus of -OMe substituted polymer decreased by 0.1-0.2 V and that of the -CN substituted polymer increased by 0.2 V. [204] Besides, the triphenylamine, [205] 2,4,6-triphenyl-1,3,5-triazine (Tz), 1,3,5-triphenylbenzene (Bz) [206] were utilized to replace the phenyl in p-DPPZ, forming highly-crosslinked structures.…”

“…MCAP is commonly used for the synthesis of RPs [143] and PQs [3] with polynorbornene backbone. Polycondensation is extensively used in the synthesis of PQs, [40] PIs, [214] IPs, [201][202][203] and mainchain TEPs [169] (or DSPs [187] ). Understanding the polymerization mechanism is helpful to put forward strategies for improving polymerization degree and designing novel polymers, to obtain polymers with high MW and high performance.…”