Polyimides: Promising Energy-Storage Materials

Polymer-Based Organic Batteries

The storage of electric energy is of ever growing importance for our modern, technology-based society, and novel battery systems are in the focus of research. The substitution of conventional metals as redox-active material by organic materials offers a promising alternative for the next generation of rechargeable batteries since these organic batteries are excelling in charging speed and cycling stability. This review provides a comprehensive overview of these systems and discusses the numerous classes of organic, polymer-based active materials as well as auxiliary components of the battery, like additives or electrolytes. Moreover, a definition of important cell characteristics and an introduction to selected characterization techniques is provided, completed by the discussion of potential socio-economic impacts.

A hyperbranched conjugated Schiff base polymer network: a potential negative electrode for flexible thin film batteries

A hyperbranched conjugated Schiff base polymer network was synthesized by condensation between 4,4',4''-nitrilotribenzaldehyde and p-phenylenediamine. The material exhibits excellent rate capability and long cycle life for lithium storage. Coupled with lower electrode potential (0.7 V vs. Li(+)/Li), it may be well suited for fully flexible thin film polymeric batteries as the negative electrode.

Heteroaromatic organic compound with conjugated multi-carbonyl as cathode material for rechargeable lithium batteries

The heteroaromatic organic compound, N,N’-diphenyl-1,4,5,8-naphthalenetetra- carboxylic diimide (DP-NTCDI-250) as the cathode material of lithium batteries is prepared through a simple one-pot N-acylation reaction of 1,4,5,8-naphthalenetetra-carboxylic dianhydride (NTCDA) with phenylamine (PA) in DMF solution followed by heat treatment in 250 °C. The as prepared sample is characterized by the combination of elemental analysis, NMR, FT-IR, TGA, XRD, SEM and TEM. The electrochemical measurements show that DP-NTCDI-250 can deliver an initial discharge capacity of 170 mAh g⁻¹ at the current density of 25 mA g⁻¹. The capacity of 119 mAh g⁻¹ can be retained after 100 cycles. Even at the high current density of 500 mA g⁻¹, its capacity still reaches 105 mAh g⁻¹, indicating its high rate capability. Therefore, the as-prepared DP-NTCDI-250 could be a promising candidate as low cost cathode materials for lithium batteries.

Improving the Performance of Lithium-Sulfur Batteries by Employing Polyimide Particles as Hosting Matrixes

Sulfur cathodes with four polyimide (PI) compounds as hosting matrixes have been prepared through a simple one-step approach. These four PIs-S composites exhibited higher sulfur utilization and better cycling stability than pure sulfur. At a current rate of 300 mA g(-1), the initial discharge capacities of PI-1S, PI-2S, PI-3S, and BBLS reached 1120, 1100, 1150, and 1040 mAh g(-1), respectively. After the 30th cycle, PI-1S, PI-2S, PI-3S, BBLS and pristine sulfur powder still remained discharge capacities of 715, 673, 729, 643, and 550 mAh g(-1). Especially, PI-1S and PI-3S cathodes exhibit excellent cycling stability with the discharge capacities of 522 and 574 mAh g(-1) at the 450th cycle, respectively.

Nitrogen-Doped Porous Carbon Superstructures Derived from Hierarchical Assembly of Polyimide Nanosheets

3D carbon superstructures are fabricated through the hierarchical assembly of polyimide nanosheets and thermal treatment. Benefiting from the ultrahigh surface area and the hierarchically porous structure, along with the well-distributed highly electroactive sites, the flower-like carbon material exhibits outstanding catalytic activity toward the oxygen reduction reaction and also serves as a highly stable electrode material in supercapacitors.

Biomass-derived carbonaceous positive electrodes for sustainable lithium-ion storage

Biomass derived carbon materials have been widely used as electrode materials; however, in most cases, only electrical double layer capacitance (EDLC) is utilized and therefore, only low energy density can be achieved. Herein, we report on redox-active carbon spheres that can be simply synthesized from earth-abundant glucose via a hydrothermal process. These carbon spheres exhibit a specific capacity of ∼210 mA h gCS(-1), with high redox potentials in the voltage range of 2.2-3.7 V vs. Li, when used as positive electrode in lithium cells. Free-standing, flexible composite films consisting of the carbon spheres and few-walled carbon nanotubes deliver high specific capacities up to ∼155 mA h gelectrode(-1) with no obvious capacity fading up to 10,000 cycles, proposing to be promising positive electrodes for lithium-ion batteries or capacitors. Furthermore, considering that the carbon spheres were obtained in an aqueous glucose solution and no toxic or hazardous reagents were used, this process opens up a green and sustainable method for designing high performance, environmentally-friendly energy storage devices.

A graphene supported polyimide nanocomposite as a high performance organic cathode material for lithium ion batteries

Organic electrode materials are promising and future candidates for applications such as cathode in green lithium-ion batteries (LIBs).

Environmentally-friendly aqueous Li (or Na)-ion battery with fast electrode kinetics and super-long life

Current rechargeable batteries generally display limited cycle life and slow electrode kinetics and contain environmentally unfriendly components. Furthermore, their operation depends on the redox reactions of metal elements. We present an original battery system that depends on the redox of I(-)/I3 (-) couple in liquid cathode and the reversible enolization in polyimide anode, accompanied by Li(+) (or Na(+)) diffusion between cathode and anode through a Li(+)/Na(+) exchange polymer membrane. There are no metal element-based redox reactions in this battery, and Li(+) (or Na(+)) is only used for charge transfer. Moreover, the components (electrolyte/electrode) of this system are environment-friendly. Both electrodes are demonstrated to have very fast kinetics, which gives the battery a supercapacitor-like high power. It can even be cycled 50,000 times when operated within the electrochemical window of 0 to 1.6 V. Such a system might shed light on the design of high-safety and low-cost batteries for grid-scale energy storage.

Poly(norbornyl-NDIs) as a potential cathode-active material in rechargeable charge storage devices

Two pendant-type naphthalene diimide (NDI) polymers bearing a polynorbornene backbone were prepared and their electrochemical properties explored.

A polyimide–MWCNTs composite as high performance anode for aqueous Na-ion batteries

A PNP@CNT electrode demonstrates a high reversible capacity of 149 mA h g⁻¹ at quite a low potential of −0.65 V (vs. SCE), superior rate capability and long-term cycling stability over 500 cycles.

In situ growth of polyphosphazene nanoparticles on graphene sheets as a highly stable nanocomposite for metal-free lithium anodes

A polyphosphazene/GN nanocomposite was readily synthesized by thermal polymerization of hexachlorocyclotriphosphazene with graphene oxide, which exhibits a stable and uniform nanostructure.

Large-Area Polyimide/SWCNT Nanocable Cathode for Flexible Lithium-Ion Batteries

A large-area flexible polymer electrode is fabricated using a new type of polyimide/single-walled carbon nanotube (SWCNT) nanocable composite. SWCNTs serve as the current collector and conductive network, and polyimide nanoparticles anchored on carbon nanotubes act as active materials. The electrode shows superior rate performance, good cycling stability, and high flexibility.

Poly(benzoquinonyl sulfide) as a High-Energy Organic Cathode for Rechargeable Li and Na Batteries

In concern of resource sustainability and environmental friendliness, organic electrode materials for rechargeable batteries have attracted increasing attentions in recent years. However, for many researchers, the primary impression on organic cathode materials is the poor cycling stability and low energy density, mainly due to the unfavorable dissolution and low redox potential, respectively. Herein, a novel polymer cathode material, namely poly(benzoquinonyl sulfide) (PBQS) is reported, for either rechargeable Li or Na battery. Remarkably, PBQS shows a high energy density of 734 W h kg^-1 (2.67 V × 275 mA h g^-1) in Li battery, or 557 W h kg^-1 (2.08 V × 268 mA h g^-1) in Na battery, which exceeds those of most inorganic Li or Na intercalation cathodes. Moreover, PBQS also demonstrates excellent long-term cycling stability (1000 cycles, 86%) and superior rate capability (5000 mA g^-1, 72%) in Li battery. Besides the exciting battery performance, investigations on the structure-property relationship between benzoquinone (BQ) and PBQS, and electrochemical behavior difference between Li-PBQS battery and Na-PBQS battery, also provide significant insights into developing better Li-organic and Na-organic batteries beyond conventional Li-ion batteries.

High-performance sodium batteries with the 9,10-anthraquinone/CMK-3 cathode and an ether-based electrolyte

We here report a much improved electrochemical performance of sodium batteries with the 9,10-anthraquinone (AQ) cathode encapsulated in CMK-3, an ether-based electrolyte of high-concentration CF3SO3Na (NaTFS) as a sodium salt in triethylene glycol dimethyl ether (TEGDME) solvent, and the Na anode.

Electrochemical polymerization of pyrene derivatives on functionalized carbon nanotubes for pseudocapacitive electrodes

Electrochemical energy-storage devices have the potential to be clean and efficient, but their current cost and performance limit their use in numerous transportation and stationary applications. Many organic molecules are abundant, economical and electrochemically active; if selected correctly and rationally designed, these organic molecules offer a promising route to expand the applications of these energy-storage devices. In this study, polycyclic aromatic hydrocarbons are introduced within a functionalized few-walled carbon nanotube matrix to develop high-energy, high-power positive electrodes for pseudocapacitor applications. The reduction potential and capacity of various polycyclic aromatic hydrocarbons are correlated with their interaction with the functionalized few-walled carbon nanotube matrix, chemical configuration and electronic structure. These findings provide rational design criteria for nanostructured organic electrodes. When combined with lithium negative electrodes, these nanostructured organic electrodes exhibit energy densities of ∼350 Wh kg⁻¹_electrode at power densities of ∼10 kW kg⁻¹_electrode for over 10,000 cycles.

Electrochemically active organic molecules are an important class of electrode materials for energy storage. Here, the authors report organic electrodes made of polycyclic aromatic hydrocarbons and functionalized few-walled carbon nanotubes, which show promising electrochemical performance.

High-Performance Organic Lithium Batteries with an Ether-Based Electrolyte and 9,10-Anthraquinone (AQ)/CMK-3 Cathode

Organic carbonyl electrode materials of lithium batteries have shown multifunctional molecule design and high capacity, but have the problems of poor cycling and low rate performance due to their high solubility in traditional carbonate-based electrolytes and low conductivity. High-performance organic lithium batteries with modified ether-based electrolyte (2 m LiN(CF₃SO₂)₂ in 1,3-dioxolane/dimethoxyethane solvent with 1% LiNO₃ additive (2m-DD-1%L)) and 9,10-anthraquinone (AQ)/CMK-3 (AQC) nanocomposite cathode are reported here. The electrochemical results manifest that 2m-DD-1%L electrolyte promotes the cycling performance due to the restraint of AQ dissolution in ether-based electrolyte with high Li salt concentration and formation of a protection film on the surface of the anode. Additionally, the AQC nanocomposite improves the rate performance because of the nanoconfinement effect of CMK-3 and the decrease of charge transfer impedance. In 2m-DD-1%L electrolyte, AQC nanocomposite delivers an initial discharge capacity of 205 mA h g^-1 and a capacity of 174 mA h g^-1 after 100 cycles at 0.2 C. Even at a high rate of 2 C, its capacity is 146 mA h g^-1. This strategy is also used for other organic carbonyl compounds with quinone substructures and they maintain high stable capacities. This sheds light on the development of advanced organic lithium batteries with carbonyl electrode materials and ether-based electrolytes.

Heavily n-Dopable π-Conjugated Redox Polymers with Ultrafast Energy Storage Capability

We report here the first successful demonstration of a "π-conjugated redox polymer" simultaneously featuring a π-conjugated backbone and integrated redox sites, which can be stably and reversibly n-doped to a high doping level of 2.0 with significantly enhanced electronic conductivity. The properties of such a heavily n-dopable polymer, poly{[N,N'-bis(2-octyldodecyl)-1,4,5,8-naphthalenedicarboximide-2,6-diyl]-alt-5,5'-(2,2'-bithiophene)} (P(NDI2OD-T2)), were compared vis-à-vis to those of the corresponding backbone-insulated poly{[N,N'-bis(2-octyldodecyl)-1,4,5,8-naphthalenedicarboximide-2,6-diyl]-alt-5,5'-[2,2'-(1,2-ethanediyl)bithiophene]} (P(NDI2OD-TET)). When evaluated as a charge storage material for rechargeable Li batteries, P(NDI2OD-T2) delivers 95% of its theoretical capacity at a high rate of 100C (72 s per charge-discharge cycle) under practical measurement conditions as well as 96% capacity retention after 3000 cycles of deep discharge-charge. Electrochemical, impedance, and charge-transport measurements unambiguously demonstrate that the ultrafast electrode kinetics of P(NDI2OD-T2) are attributed to the high electronic conductivity of the polymer in the heavily n-doped state.

Renewable-juglone-based high-performance sodium-ion batteries

A renewable-biomolecule-based electrode is developed through a facile synchronous reduction and self-assembly process, without any binder or additional conductive agent. The hybridized electrodes can be fabricated with arbitrary size and shape and exhibit superior capacity and cycle performance. The renewable-biomaterial-based high-performance electrodes will hold a place in future energy-storage devices.

Electrochemically active, crystalline, mesoporous covalent organic frameworks on carbon nanotubes for synergistic lithium-ion battery energy storage

Organic batteries free of toxic metal species could lead to a new generation of consumer energy storage devices that are safe and environmentally benign. However, the conventional organic electrodes remain problematic because of their structural instability, slow ion-diffusion dynamics, and poor electrical conductivity. Here, we report on the development of a redox-active, crystalline, mesoporous covalent organic framework (COF) on carbon nanotubes for use as electrodes; the electrode stability is enhanced by the covalent network, the ion transport is facilitated by the open meso-channels, and the electron conductivity is boosted by the carbon nanotube wires. These effects work synergistically for the storage of energy and provide lithium-ion batteries with high efficiency, robust cycle stability, and high rate capability. Our results suggest that redox-active COFs on conducting carbons could serve as a unique platform for energy storage and may facilitate the design of new organic electrodes for high-performance and environmentally benign battery devices.

Redox-active polyimide–polyether block copolymers as electrode materials for lithium batteries

Excellent cyclability of polyimide–polyether block copolymers used as cathode materials in lithium batteries was demonstrated.

Cyclic aromatic imides as a potential class of molecules for supramolecular interactions

Prospects of stacking interactions of imides beneficial to generation of new soft materials are projected by analysing examples of primary building blocks that provide a basis for understanding at the molecular level.

Synthesis of ordered mesoporous phenanthrenequinone-carbon via π-π interaction-dependent vapor pressure for rechargeable batteries

The π-π interaction-dependent vapour pressure of phenanthrenequinone can be used to synthesize a phenanthrenequinone-confined ordered mesoporous carbon. Intimate contact between the insulating phenanthrenequinone and the conductive carbon framework improves the electrical conductivity. This enables a more complete redox reaction take place. The confinement of the phenanthrenequinone in the mesoporous carbon mitigates the diffusion of the dissolved phenanthrenequinone out of the mesoporous carbon, and improves cycling performance.

Synthesis and characterization of thermally stable, hydrophobic hyperbranched polyimides derived from a novel triamine

A novel aromatic triamide 1,3,5-tri[4-(4-aminophenoxy)phenyl] benzene (TAPOPB) with prolonged chain segments and ether bonds was successfully prepared through a three-step reaction. Then a series of hyperbranched polyimides (HBPIs) were synthesized using A2 + B3 polycondensation from various commercial aromatic dianhydrides and TAPOPB. The HBPIs showed good solubility, thermal stability with glass transition temperatures ( Tg) between 218°C and 320°C, and temperature at 10% weight loss of 502.1–561.7°C in nitrogen atmosphere. Meanwhile, they had decent mechanical properties whose tensile strength and modulus were higher than 72.37 MPa and 1.039 GPa, respectively. Water uptake of less than 0.96% was obtained. The truncation wavelengths of the films were all greater than 400 nm with a good application prospect in UV protective coating. Most contact angles were more than 90°, promising to be used as hydrophobic material.

Environmentally-friendly lithium recycling from a spent organic li-ion battery

A simple and straightforward method using non-polluting solvents and a single thermal treatment step at moderate temperature was investigated as an environmentally-friendly process to recycle lithium from organic electrode materials for secondary lithium batteries. This method, highly dependent on the choice of electrolyte, gives up to 99% of sustained capacity for the recycled materials used in a second life-cycle battery when compared with the original. The best results were obtained using a dimethyl carbonate/lithium bis(trifluoromethane sulfonyl) imide electrolyte that does not decompose in presence of water. The process implies a thermal decomposition step at a moderate temperature of the extracted organic material into lithium carbonate, which is then used as a lithiation agent for the preparation of fresh electrode material without loss of lithium.

Electrochemical Properties of Poly(Anthraquinonyl Sulfide)/Graphene Sheets Composites as Electrode Materials for Electrochemical Capacitors

Poly(anthraquinonyl sulfide) (PAQS)/graphene sheets (GSs) composite was synthesized through in situ polymerization to evaluate its performance as an electrode material for electrochemical capacitors. PAQS was successfully synthesized in the presence of GSs with uniform distribution. PAQS/GSs showed a pair of reversible redox peaks at around 0 V (vs. Ag/AgCl). The specific capacitance of PAQS/GSs was 349 F·g⁻¹ (86 mAh·g⁻¹) at a current density of 500 mA·g⁻¹, and a capacitance of 305 F·g⁻¹ was maintained even at a high current density of 5000 mA·g⁻¹. The in situ polymerization of PAQS with GSs facilitated their interaction and enabled faster charge transfer and redox reaction, resulting in enhanced electrode properties.

Flexible and binder-free organic cathode for high-performance lithium-ion batteries

Fabrication of a flexible organic electrode by growing polyimide nanoflakes on single-wall carbon nanotube films is presented. The flexible electrode exhibits high capacity and outstanding rate capability. This electrode is promising for the application in high-power flexible lithium-Ion batteries.

Organic nanohybrids for fast and sustainable energy storage

A nanohybridization strategy is presented for the fabrication of high performance lithium ion batteries based on redox-active organic molecules. The rearrangement of electroactive aromatic molecules from bulk crystalline particles into molecular layers is achieved by non-covalent nanohybridization of active molecules with conductive scaffolds. As a result, nano-hybrid organic electrodes in the form of a flexible self-standing paper-free of binder/additive and current collector-are synthesized, which exhibit high energy and power densities combined with excellent cyclic stability.