Perylenedianhydride-Based Polyimides as Organic Cathodes for Rechargeable Lithium and Sodium Batteries

Abstract

Organic carbonyl molecules have recently been investigated as redox-active electrode materials in rechargeable organic batteries (ROBs), and although redox-active polymers offer high specific energy density and tunable redox potential windows, their undesirable dissolution into aprotic electrolytes during charge/discharge cycling and their poor electronic conductivity compromised their utilization in ROBs. To overcome these challenges, we synthesized, for the first time, two 3,4:9,10-perylenetetracarboxylic dianhydride (PTCDA)-based polyimides, namely, perylenediimide-benzidine (PDI-Bz) and perylenediimide-urea (PDI-Ur), and utilized them as organic cathode materials for lithium-ion batteries and sodium-ion batteries. These cathode materials are synthesized through imidization of a non-bay-substituted PTCDA unit by using bifunctional amine compounds (i.e., benzidine and carbonyl diamine (urea)) via a simple one-step reaction. Our organic metal-ion batteries employing PDI-Bz demonstrate a high discharge capacity of 120 mAh/g (with a reversible capacity of ∼54 mAh/g) vs Li + /Li and the second discharge capacity of 111 mAh/g (∼74 mAh/g) vs Na + /Na with two discharge voltage plateaus in the range of 1.9−2.4 V. The cells retained a capacity retention of 46% vs Li + /Li and 55.2% vs Na + /Na over 50 cycles. PDI-Ur exhibits higher lithiation capacity of ∼119 mAh/g at the 14th cycling (increased discharge capacity of ∼118 mAh/g at the 25th cycling). In SIBs, PDI-Ur shows an initial discharge capacity of ∼119 mAh/g with a single discharge voltage plateau around 1.9 V vs Na + /Na and the capacity retention of ∼78.7% (∼93 mAh/g) over 50 cycles, both of which are suggesting a potential feasibility of these PTCDA-based polyimides as promising organic cathode materials for high-capacity metal-ions batteries.

Large π-Conjugated Condensed Perylene-Based Aromatic Polyimide as Organic Cathode for Lithium-Ion Batteries

“…The new vibrational peaks detected at 712 and 713 cm –1 are assigned to imide CO symmetric in-plane bending of BA-PI and PI, respectively. These result indicated that the complete conversion of the anhydride groups into the imide functionality in both BA-PI and PI during polymerization reaction …”

“…The Raman spectroscopic method was used to identify the molecular vibrational modes of BA-PI and PI (Figure S3). BA-PI has four main Raman modes with frequencies of 1185 cm –1 (C–C stretching of the perylene core and C–H in-plane bending), 1364 cm –1 (CH in-plane bending), 1458 cm –1 (CH wagging on the pyrene ring), 1575 cm –1 (CC/C–C stretching of the perylene core coupled with CH wagging), 1895 cm –1 (CO symmetric stretching of perylene core), and 646 cm –1 (C–N–C stretching of the imide group in polyimide). , PI exhibits similar Raman modes with frequencies of 1063 cm –1 (C–C stretching/C–H bending), 1300 cm –1 (C–H bending), 1367 cm –1 (C–H wagging on the aromatic ring), 1563 cm –1 (CC/C–C stretching), 1674 cm –1 (CO symmetric stretching of perylene ring), and 648 cm –1 (C–N–C stretching).…”

“…The cell based on BA-PI reached a Coulombic efficiency of almost 100%, indicating efficient suppression of electrode loss during the charge/discharge process. The capacity loss in BA-PI over 50 cycles suggests that the insertion of lithium in the amorphous structure of BA-PI is not fully reversible and further agglomeration of BA-PI occurs during charge/discharge cycling. ,, As illustrated in Scheme , each aromatic dianhydride unit of BA-PI could undergo an enolization reaction with the oxygen atoms of four-carbonyl groups upon the insertion of Li + ions. The subsequent insertion and deinsertion of Li + ions occurs in three consecutive steps as depicted in Scheme .…”

“…Thus, PI shows good cycling performance and rate capability in LIBs compared to BA-PI. However, the observed poor rate capabilities at higher current rates in PI might be related to the dissolution of the discharged product of PI 2 – ·2Li + (i.e., electrogenerated 2Li + enolate species of PI). , …”

“…This would lead to high specific energy, long-life cyclability and high rate capability. − However, there are several limitations to these conjugated carbonyl compounds, in particular, poor electronic conductivity and solubility into the liquid electrolytes. To overcome these issues, recent studies have explored the use of perylene-based aromatic polyimides containing a large π-conjugated condensed aromatic ring and four carbonyl groups and its nanocomposite with carbon-based materials as highly promising electrode materials with high electronic conductivity for ultralong-life organic batteries. , Very recent studies from our group showed that the aromatic polyimides derived from an aromatic dianhydride of perylene-3,4:9,10-tetracarboxylic acid (PTCDA) with diamine compounds have the potential for storage of both lithium and sodium ions, with a high discharge capacity of ∼120 mAh g –1 and good cycle stability over 50 cycles …”