A triphenylamine-based polymer with anthraquinone side chain as cathode material in lithium ion batteries

Regulating the Metal Nodes of In Situ Electropolymerized Metal-Organic Coordination Polymers for High Performance LIBs

Metal-organic coordination polymers (MOPs) comprised of redox-active organic moieties and metal ions emerge as an important class of electroactive materials for battery applications. The bipolar two transition metal-based (Fe and Co) coordination complexes bearing terpyridine-triphenylamine ligand are used as models to investigate the relationships between structure and electrochemical performance. It turned out that the choice of central metal atom has a profound influence on the practical voltage window and specific capacity. The high-performing poly(FeL)n electrode exhibits a reversible capacity of 272.5 mAh g-1 after 100 cycles at 50 mA g-1, excellent cycling stability up to 4000 cycles at 5A g-1 (capacity ration:83.1%), and excellent rate capacity. The poly(CoL)n electrode exhibits a significantly lower capacity of 107 mAh g-1 at the 100th cycle and inferior stability (54 mAh g-1 after 4000 cycles at 5A g-1, capacity retention: 38.7%). DFT analysis indicates that the metal center directly influences the electron cloud density of the metal-terpyridine structure, which in turn affects the redox activity of the polymer by varying the affinity to lithium ions and the charge transfer efficiency. These findings highlight the importance of metal centers in coordination polymers, providing direct guidance for the exploration of MOPs as novel resource-friendly cathode materials.

Novel triphenylamine-based polyimides as promising organic cathode for lithium/sodium-ion batteries

Organic carbonyl cathode materials are expected to be excellent candidates for widespread application in next-generation lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) owing to their high theoretical specific capacity, low cost, sustainability, environmental friendliness, and structural diversity. However, organic carbonyl cathode materials face some key challenges, including high solubility in organic electrolytes and low discharge platform, which hinder their practical applications. Herein, a novel poly(4-aminotriphenylamine-3,3',4,4'-benzophenone tetramide) (PTNBI) electrode has been synthesized through the polymerization of 4-aminotriphenylamine with 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA), addressing the two crucial issues of solubility and low discharge platform. As a cathode material for LIBs, the PTNBI electrode exhibits a high discharge platform of 3.5 V, and a good initial specific discharge capacity of ∼135 mA h g-1 at 50 mA g-1, whilst retaining good cycling stability after 100 cycles. The CV curves show that the redox potentials (∼3.5 V/∼4.0 V) correspond to the process of de-doping/doping of the PF6 - anions at the triphenylamine unit, whilst the redox potentials (∼2.26 V/∼2.41 V) correspond to the insertion/extraction of lithium ions at the carbonyl group of the anhydride. Meanwhile, as a cathode material for SIBs, the PTNBI electrode delivers a discharge platform of 3.0 V, and an initial specific discharge capacity of ∼106 mA h g-1 at 50 mA g-1 with remarkable cycling performance. The PTNBI material incorporates a triphenylamine unit with a high discharge voltage and a carbonyl anhydride with high theoretical capacity, which effectively addresses the issues of low discharge platform and high solubility, thereby enhancing the specific capacity. This approach provides guidance for other organic electrode materials by tackling high solubility and low discharge platform challenges.

Advanced Porous Aromatic Frameworks: A Comprehensive Overview of Emerging Functional Strategies and Potential Applications

Porous aromatic frameworks (PAFs) are a fundamental group of porous materials characterized by their distinct structural features and large surface areas. These materials are synthesized from aromatic building units linked by strong carbon-carbon bonds, which confer exceptional rigidity and long-term stability. PAFs functionalities may arise directly from the intrinsic chemistry of their building units or through the postmodification of aromatic motifs using well-defined chemical processes. Compared to other traditional porous materials such as zeolites and metallic-organic frameworks, PAFs demonstrate superior stability under severe chemical treatments due to their robust carbon-carbon bonding. Even in challenging environments, the chemical stability and ease of functionalization of PAFs demonstrate their flexibility and specificity. Research on PAFs has significantly expanded and accelerated over the past decade, necessitating a comprehensive overview of key advancements in this field. This review provides an in-depth analysis of the recent advances in the synthesis, functionalization, and dimensionality of PAFs, along with their distinctive properties and wide-ranging applications. This review explores the innovative methodologies in PAFs synthesis, the strategies for functionalizing their structures, and the manipulation of their dimensionality to tailor their properties for specific potential applications. Similarly, the key application areas, including batteries, absorption, sensors, CO2 capture, photo-/electrocatalytic usages, supercapacitors, separation, and biomedical are discussed in detail, highlighting the versatility and potential of PAFs in addressing modern scientific and industrial challenges.

Triphenylamine-Based Conjugated Microporous Polymers as the Next Generation Organic Cathode Materials

This paper presents a study on a novel porous polymer based on triphenylamine (LPCMP) as an excellent cathode material for lithium-ion batteries. Through structural design and a scalable post-synthesis approach, improvements in intrinsic conductivity, practical capacity, and redox potential in an organic cathode material is reported. The designed cathode achieves a notable capacity of 146 mAh g⁻¹ with an average potential of 3.6 V, using 70% active material content in the electrode. Additionally, through appropriate structural design, the capacity can increase to 160 mAh g-1. Even at a high current density of 20 A g⁻¹ (360C), the cathode maintains a capacity of 74 mAh g⁻¹, enabling full charge within 10 s. A high specific energy density of 569 Wh kg⁻¹ (at 0.1 A g⁻¹) is combined with a very high power density of 94.5 kW kg⁻¹ (at 20 A g⁻¹ corresponding to a specific energy density of 263 Wh kg⁻¹) surpassing the power density of graphene-based supercapacitors. It exhibits highly stable cyclic performance across various current densities, retaining almost 95% of its initial capacity after 1000 cycles at 5.5C. This work presents a significant breakthrough in developing high-capacity, high-potential organic materials for sustainable, high-energy, and high-power lithium-ion batteries.

Redox-active, photoluminescent porous polymers based on spirofluorene-bridged N-heterotriangulenes and their feasibility as organic cathode materials

Novel microporous polymers were synthesized through Yamamoto polymerization of selectively brominated spirofluorene-bridged N-heterotriangulenes. Extensive characterization, including combustion analysis, ToF-SIMS, IR, and Raman spectroscopy, confirmed the elemental composition and integrity of the polymers. The amorphous polymers, observed by scanning electron microscopy as globular particles aggregating into larger structures, exhibited remarkable thermal stability (decomposition temperatures > 400 °C) and BET surface areas up to 690 m2 g-1. Dispersions of the tert-butyl-substituted polymer in different solvents displayed bathochromically shifted emission with remarkable solvatochromism. The polymer is reversibly oxidized at +3.81 V (vs. Li/Li+) in composite electrodes with carbon black and reaches specific capacities up to 26 mA h g-1 and excellent cycling stability when implemented as cathode material in lithium-ion batteries. Our results highlight the potential of spirofluorene-bridged N-heterotriangulenes as versatile building blocks for the development of functional redox-active porous polymers.

Redox-Active High-Performance Polyimides as Versatile Electrode Materials for Organic Lithium- and Sodium-Ion Batteries

Organic electrode materials for rechargeable batteries show great promise for improving the storage capacity, reducing production costs, and minimizing environmental impact toward sustainability. In this study, we report a series of newly synthesized arylamine-based polyimides, TPPA-PIs, with three different bridge functionalizations on the imide rings and isomeric constituents that can work as versatile battery electrodes. As a lithium-ion battery cathode, a maximum energy density of 248 Wh kg-1 with high voltage operation up to 4.0 V can be achieved. As a lithium-ion battery anode, the TPPA-PIs showed a reversible storage capacity of 806 mA h g-1 at 100 mA g-1 current density with good rate capability up to a current density of 2000 mA g-1. Moreover, when applied as sodium-ion battery anodes, TPPA-PIs delivered an optimum specific capacity of up to 218 mA h g-1 after 50 cycles at a 50 mA g-1 current density and revealed a long cycling stability up to 1000 cycles under a high current density of 1000 mA g-1. More importantly, these electrochemical performances of TPPA-PIs are among the best compared with other reported polymer-based electrodes. The mechanistic studies show that both bridge functionalization on the imide units and isomerism impact the electrochemical performance by regulating their intrinsic properties such as charge storage behavior, ion diffusivity, and activation energy. We believe that such a detailed study of the structural design to electrochemical performance of these polymeric electrodes will offer insights into materials development and optimization for next-generation multifunctional energy storage devices in a wide range of applications.

Rational Design of Naphthol Groups Functionalized Bipolar Polymer Cathodes for High Performance Alkali-Ion Batteries

Redox-active organic compounds gather significant attention for their potential application as electrodes in alkali ion batteries, owing to the structural versatility, environmental friendliness, and cost-effectiveness. However, their practical applications of such compounds are impeded by insufficient active sites with limited capacity, dissolution in electrolytes, and sluggish kinetics. To address these issues, a naphthol group-containing triarylamine polymer, namely poly[6,6'-(phenylazanediyl)bis(naphthol)] (poly(DNap-OH)) is rationally designed and synthesized, via oxidative coupling polymerization. It is capable of endowing favorable steric structures that facilitate fast ion diffusion, excellent chemical stability in organic electrolytes, and additional redox-active sites that enable a bipolar redox reaction. By exploiting these advantages, poly(DNap-OH) cathodes demonstrate remarkable cycling stability in both lithium-ion batteries (LIBs) and potassium-ion batteries (PIBs), showcasing enhanced specific capacity and redox reaction kinetics in comparison to the conventional poly(4-methyltriphenylamine) cathodes. Overall, this work offers insights into molecular design strategies for the development of high-performance organic cathodes in alkali-ion batteries.

Donor-acceptor type triphenylamine-based porous aromatic frameworks (TPA-PAFs) for photosynthesis of benzimidazoles

The development of efficient and recyclable photocatalysts for organic synthesis is of great interest. This study presents the synthesis of triphenylamine-based porous aromatic frameworks (TPA-PAFs) in an alternating donor-acceptor (D-A) manner. The light absorption range and the optical band gaps of TPA-PAFs are effectively tuned by changing the electron acceptor units, which further determine their photocatalytic properties. As a result, TPA-PAFs exhibit excellent catalytic performance for the photosynthesis of benzimidazoles in high yields (up to 99%), broad substrate scope (18 examples), and good recyclability (up to 10 cycles). This work provides a feasible approach toward the facile design and synthesis of efficient and stable PAF-based photocatalysts, which further broadens the application of PAFs catalytic materials in photocatalytic organic synthesis.

Bio-Based Polyhydroxyanthraquinones as High-Voltage Organic Electrode Materials for Batteries

Organic materials have gained much attention as sustainable electrode materials for batteries. Especially bio-based organic electrode materials (OEMs) are very interesting due to their geographical independency and low environmental impact. However, bio-based OEMs for high-voltage batteries remain scarce. Therefore, in this work, a family of bio-based polyhydroxyanthraquinones (PHAQs)-namely 1,2,3,4,5,6,7,8-octahydroxyanthraquinone (OHAQ), 1,2,3,5,6,7-hexahydroxyanthraquinone (HHAQ), and 2,3,6,7-tetrahydroxyanthraquinone (THAQ)-and their redox polymers were synthesized. These PHAQs were synthesized from plant-based precursors and exhibit both a high-potential polyphenolic redox couple (3.5-4.0 V vs Li/Li+) and an anthraquinone redox moiety (2.2-2.8 V vs Li/Li+), while also showing initial charging capacities of up to 381 mAh g-1. To counteract the rapid fading caused by dissolution into the electrolyte, a facile polymerization method was established to synthesize PHAQ polymers. For this, the polymerization of HHAQ served as a model reaction where formaldehyde, glyoxal, and glutaraldehyde were tested as linkers. The resulting polymers were investigated as cathode materials in lithium metal batteries. PHAQ polymer composites synthesized using formaldehyde as linker and 10 wt % multiwalled carbon nanotubes (MWCNTs), namely poly(THAQ-formaldehyde)-10 wt % MWCNTs and poly(HHAQ-formaldehyde)-10 wt % MWCNTs, exhibited the best cycling performance in the lithium metal cells, displaying a high-voltage discharge starting at 4.0 V (vs Li/Li+) and retaining 81.6 and 77.3 mAh g-1, respectively, after 100 cycles.

Nonconjugated Redox-Active Polymers: Electron Transfer Mechanisms, Energy Storage, and Chemical Versatility

The storage of electric energy in a safe and environmentally friendly way is of ever-growing importance for a modern, technology-based society. With future pressures predicted for batteries that contain strategic metals, there is increasing interest in metal-free electrode materials. Among candidate materials, nonconjugated redox-active polymers (NC-RAPs) have advantages in terms of cost-effectiveness, good processability, unique electrochemical properties, and precise tuning for different battery chemistries. Here, we review the current state of the art regarding the mechanisms of redox kinetics, molecular design, synthesis, and application of NC-RAPs in electrochemical energy storage and conversion. Different redox chemistries are compared, including polyquinones, polyimides, polyketones, sulfur-containing polymers, radical-containing polymers, polyphenylamines, polyphenazines, polyphenothiazines, polyphenoxazines, and polyviologens. We close with cell design principles considering electrolyte optimization and cell configuration. Finally, we point to fundamental and applied areas of future promise for designer NC-RAPs.

Triphenylamine-anthraquinone based donor-acceptor conjugated microporous polymers for photocatalytic hydroxylation of phenylboronic acids

Triphenylamine-based donor-acceptor conjugated microporous polymers, namely PTPA-AQ and PTPA-AM, were synthesized for the first time via Suzuki-Miyaura coupling of tris(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)-amine as a donor with 2,6-dibromoanthracene-9,10-dione and 2,2'-(2,6-dibromoanthracene-9,10-diylidene)dimalononitrile acceptors for efficient visible-light driven oxidative hydroxylation of various phenylboronic acids. The dimalononitrile derivative having greater acceptor ability showed tunable photophysical properties of PTPA-AM (lower band gap of 1.47 eV and better exciton separation efficiency) as well as porosity (lower Brunauer-Emmett-Teller (BET) surface area of 43 m² g^-1). PTPA-AQ having higher BET surface area (400 m² g^-1), suitable HOMO-LUMO positions and an optimal band gap (1.94 eV) showed better photocatalytic activity for the hydroxylation with yields up to 96%.

Highly electrochemically and thermally stable donor–π–acceptor triphenylamine-based hole-transporting homopolymers via oxidative polymerization

Polymers combining high electrochemical and thermal stability, good solubility, high Tg and high coke residue with low-lying HOMO levels and reasonable hole mobilities in thin films are reported in this study.

Metal-organic framework based electrode materials for lithium-ion batteries: a review

Metal-organic frameworks (MOFs) with efficient surface and structural properties have risen as a distinctive class of porous materials through the last few decades, which has enabled MOFs to gain attention in a wide range of applications like drug delivery, gas separation and storage, catalysis and sensors. Likewise, they have also emerged as efficient active materials in energy storage devices owing to their remarkable conducting properties. Metal-organic frameworks (MOFs) have garnered great interest in high-energy-density rechargeable batteries and super-capacitors. Herein the study presents their expanding diversity, structures and chemical compositions which can be tuned at the molecular level. It also aims to evaluate their inherently porous framework and how it facilitates electronic and ionic transportation through the charging and discharging cycles of lithium-ion batteries. In this review we have summarized the various synthesis paths to achieve a particular metal-organic framework. This study focuses mainly on the implementation of metal-organic frameworks as efficient anode and cathode materials for lithium-ion batteries (LIBs) with an evaluation of their influence on cyclic stability and discharge capacity. For this purpose, a brief assessment is made of recent developments in metal-organic frameworks as anode or cathode materials for lithium-ion batteries which would provide enlightenment in optimizing the reaction conditions for designing a MOF structure for the battery community and electrochemical energy storage applications.

Dicyanotriphenylamine-Based Polyimides as High-Performance Electrodes for Next Generation Organic Lithium-Ion Batteries

Aromatic polyimide (PI) derivatives have recently been investigated as redox-active electrode materials for Li-ion batteries because of their high thermal stability and thermo-oxidative stability complemented by excellent solvent resistance, good electrical and mechanical properties, and chemical resistance. In this work, we report two PI derivatives from a newly synthesized 4,4'-diamino-3″,4″-dicyanotriphenylamine (DiCN-TPA) monomer and two dianhydrides, pyromellitic dianhydride (PMDA) and 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA); designated as TPA-PMPI and TPA-NTCPI, respectively, as electrode materials for Li-ion batteries. Characterizations of the PIs reveal excellent thermal stability and bipolar property. The incorporation of DiCN-TPA into the polymer structure resulted to a disordered chain arrangement, thus giving high glass transition temperatures (T_g). Electrochemical performance tests reveal that TPA-NTCPI cathode delivered a reversible specific capacity of 150 mAh g^-1 at 0.1 A g^-1 and exhibited a stability up to 1000 cycles. On the other hand, TPA-PMPI anode delivered a high specific capacity of up to 1600 mAh g^-1 at 0.1 A g^-1 after 100 cycles. The electrochemical performance of TPA-NTCPI cathode and TPA-PMPI anode are both among the best compared with other reported aromatic PI-based electrodes. The long cycle lifetime and excellent battery performance further suggest that TPA-NTCPI and TPA-PMPI are promising organic electrode materials for next generation Li-ion batteries.

Polytriphenylamine composites for energy storage electrodes: effect of pendant vs. backbone polymer architecture of the electroactive group

Polymers are an increasingly used class of materials in semiconductors, photovoltaics and energy storage. Polymers bearing triphenylamine (TPA) or its derivatives in their structures have shown promise for application in electrochemical energy storage devices. The aim of this work is to systematically synthesize polymers bearing TPA units either as pendant groups or directly along the backbone of the polymer and evaluate their performance as electrochemical energy storage electrode materials. The first was obtained via radical polymerization of an acrylate monomer bearing TPA as a side group, resulting in a non-conjugated polymer with individual redox active sites (rP). The latter was obtained by oxidative polymerization of a substituted TPA, resulting in a conjugated polymer with TPA units along its backbone (cP). These polymers were then developed into electrodes by separately blending them with multi-wall carbon nanotubes (rC and cC). The electrodes were characterized and their charge storage stability and mechanical properties were investigated for up to 1000 cycles by cyclic voltammetry, galvanostatic charge–discharge measurements and nanoindentation. The results show that cC offers a higher initial charge capacity than rC as well as improved carbon nanotube dispersion due to its conjugated structure. Although the improved dispersion results in a higher elastic modulus for cC (compared to rC), the stiffer nature of cP made it more vulnerable to degrade upon repetitive volumetric change, while with rP, the decoupled acrylate monomer remained more protected when its redox active units of TPA underwent charge–discharge cycling.

Interaction between (a) CNT-rP-CNT with CNTs sliding next to each other, (b) CNT-cP-CNT with CNTs repulsed via steric hinderance.