Rechargeable Aqueous Aluminum Organic Batteries

Charging the Future: Harnessing Nature's Designs for Bioinspired Molecular Electrodes

The transition toward electric-powered devices is anticipated to play a pivotal role in advancing the global net-zero carbon emission agenda aimed at mitigating greenhouse effects. This shift necessitates a parallel focus on the development of energy storage materials capable of supporting intermittent renewable energy sources. While lithium-ion batteries, featuring inorganic electrode materials, exhibit desirable electrochemical characteristics for energy storage and transport, concerns about the toxicity and ethical implications associated with mining transition metals in their electrodes have prompted a search for environmentally safe alternatives. Organic electrodes have emerged as promising and sustainable alternatives for batteries. This review paper will delve into the recent advancements in nature-inspired electrode design aimed at addressing critical challenges such as capacity degradation due to dissolution, low operating voltages, and the intricate molecular-level processes governing macroscopic electrochemical properties.

A phenazine-based conjugated microporous polymer as a high performing cathode for aluminium-organic batteries

One of the possible solutions to circumvent the sluggish kinetics, low capacity, and poor integrity of inorganic cathodes commonly used in rechargeable aluminium batteries (RABs) is the use of redox-active polymers as cathodes. They are not only sustainable materials characterised by their structure tunability, but also exhibit a unique ion coordination redox mechanism that makes them versatile ion hosts suitable for voluminous aluminium cation complexes, as demonstrated by the poly(quinoyl) family. Recently, phenazine-based compounds have been found to have high capacity, reversibility and fast redox kinetics in aqueous electrolytes because of the presence of a CN double bond. Here, we present one of the first examples of a phenazine-based hybrid microporous polymer, referred to as IEP-27-SR, utilized as an organic cathode in an aluminium battery with an AlCl3/EMIMCl ionic liquid electrolyte. The preliminary redox and charge storage mechanism of IEP-27-SR was confirmed by ex situ ATR-IR and EDS analyses. The introduction of phenazine active units in a robust microporous framework resulted in a remarkable rate capability (specific capacity of 116 mA h g-1 at 0.5C with 77% capacity retention at 10C) and notable cycling stability, maintaining 75% of its initial capacity after 3440 charge-discharge cycles at 1C (127 days of continuous cycling). This superior performance compared to reported Al//n-type organic cathode RABs is attributed to the stable 3D porous microstructure and the presence of micro/mesoporosity in IEP-27-SR, which facilitates electrolyte permeability and improves kinetics.

High throughput selection of organic cathode materials

Efficient and affordable batteries require the design of novel organic electrode materials to overcome the drawbacks of the traditionally used inorganic materials, and the computational screening of potential candidates is a very efficient way to identify prospective solutions and minimize experimental testing. Here we present a DFT high-throughput computational screening where 86 million molecules contained in the PUBCHEM database have been analyzed and classified according to their estimated electrochemical features. The 5445 top-performing candidates were identified, and among them, 2306 are expected to have a one-electron reduction potential higher than 4 V versus (Li/Li+ ). Analogously, one-electron energy densities higher than 800 Whkg-1 have been predicted for 626 molecules. Explicit calculations performed for certain materials show that at least 69 candidates with a two-electron energy density higher than 1300 Whkg-1 . Successful molecules were sorted into several families, some of them already commonly used electrode materials, and others still experimentally untested. Most of them are small systems containing conjugated CO, NN, or NC functional groups. Our selected molecules form a valuable starting point for experimentalists exploring new materials for organic electrodes.

Organic Cathode Materials for Rechargeable Aluminum-Ion Batteries

Organic electrode materials (OEMs) have shown enormous potential in ion batteries because of their varied structural components and adaptable construction. As a brand-new energy-storage device, rechargeable aluminum-ion batteries (RAIBs) have also received a lot of attention due to their high safety and low cost. OEMs are expected to stand out among many traditional RAIB cathode materials. However, how to improve the electrochemical performance of OEMs in RAIBs on a laboratory scale is still challenging. This work reviews and discusses the uses of conductive polymers, carbonyl compounds, imine polymers, polycyclic aromatic hydrocarbons, organic frameworks, and other organic materials as the cathodes of RAIBs, as well as energy-storage mechanisms and research progress. It is hoped that this Review can provide the design guidelines for organic cathode materials with high capacity and great stability used in aluminum-organic batteries and develop more efficient organic energy storage cathodes.

Phenoxazine Polymer-based p-type Positive Electrode for Aluminum-ion Batteries with Ultra-long Cycle Life

Aluminum-ion batteries (AIBs) are a promising candidate for large-scale energy storage due to the abundant reserves, low cost, good safety, and high theoretical capacity of Al. However, AIBs with inorganic positive electrodes still suffer from sluggish kinetics and structural collapse upon cycling. Herein, we propose a novel p-type poly(vinylbenzyl-N-phenoxazine) (PVBPX) positive electrode for AIBs. The dual active sites enable PVBPX to deliver a high capacity of 133 mAh g^-1 at 0.2 A g^-1 . More impressively, the expanded π-conjugated construction, insolubility, and anionic redox chemistry without bond rearrangement of PVBPX for AIBs contribute to an amazing ultra-long lifetime of 50000 cycles. The charge storage mechanism is that the AlCl₄ ^- ions can reversibly coordinate/dissociate with the N and O sites in PVBPX sequentially, which is evidenced by both experimental and theoretical results. These findings establish a foundation to advance organic AIBs for large-scale energy storage.

High Performance and Long-cycle Life Rechargeable Aluminum Ion Battery: Recent Progress, Perspectives and Challenges

The rising energy crisis and environmental concerns caused by fossil fuels have accelerated the deployment of renewable and sustainable energy sources and storage systems. As a result of immense progress in the field, cost-effective, high-performance, and long-life rechargeable batteries are imperative to meet the current and future demands for sustainable energy sources. Currently, lithium-ion batteries are widely used, but limited lithium (Li) resources have caused price spikes, threatening progress toward cleaner energy sources. Therefore, post-Li, batteries that utilize highly abundant materials leading to cost-effective energy storage solutions while offering desirable performance characteristics are urgently needed. Aluminum-ion battery (AIB) is an attractive concept that uses highly abundant aluminum while offering a high theoretical gravimetric and volumetric capacity of 2980 mAh g^-1 and 8046 mAh cm^-3 , respectively. As a result, intensified efforts have been made in recent years to utilize numerous electrolytes, anodes, and cathode materials to improve the electrochemical performance of AIBs, and potentially create high-performance, low-cost, and safe energy storage devices. Herein, recent progress in the electrolyte, anode, and cathode active materials and their utilization in AIBs and their related characteristics are summarized. Finally, the main challenges facing AIBs along with future directions are highlighted.

Rechargeable Aqueous Aluminum-Ion Battery: Progress and Outlook

The high cost and scarcity of lithium resources have prompted researchers to seek alternatives to lithium-ion batteries. Among emerging "Beyond Lithium" batteries, rechargeable aluminum-ion batteries (AIBs) are yet another attractive electrochemical storage device due to their high specific capacity and the abundance of aluminum. Although the current electrochemical performance of nonaqueous AIBs is better than aqueous AIBs (AAIBs), AAIBs have recently gained attention due to their low cost and enhanced safety. Extensive efforts are devoted to developing AAIBs in the last few years. Yet, it is still challenging to achieve stable electrodes with good electrochemical performance and electrolytes without side reactions. This review summarizes the recent progress in the exploration of anode and cathode materials and the selection of electrolytes of AAIBs. Lastly, the main challenges and future research outlook of high-performance AAIBs are also presented.

Heterocyclic Conjugated Polymer Nanoarchitectonics with Synergistic Redox-Active Sites for High-Performance Aluminium Organic Batteries

The development of cost‐effective and long‐life rechargeable aluminium ion batteries (AIBs) shows promising prospects for sustainable energy storage applications. Here, we report a heteroatom π‐conjugated polymer featuring synergistic C=O and C=N active centres as a new cathode material in AIBs using a low‐cost AlCl₃/urea electrolyte. Density functional theory (DFT) calculations reveal the fused C=N sites in the polymer not only benefit good π‐conjugation but also enhance the redox reactivity of C=O sites, which enables the polymer to accommodate four AlCl₂(urea)₂⁺ per repeating unit. By integrating the polymer with carbon nanotubes, the hybrid cathode exhibits a high discharge capacity and a long cycle life (295 mAh g⁻¹ at 0.1 A g⁻¹ and 85 mAh g⁻¹ at 1 A g⁻¹ over 4000 cycles). The achieved specific energy density of 413 Wh kg⁻¹ outperforms most Al–organic batteries reported to date. The synergistic redox‐active sites strategy sheds light on the rational design of organic electrode materials.

Proton-Assisted Aqueous Manganese-Ion Battery Chemistry

Aqueous manganese-ion batteries (MIBs) are promising energy storage systems because of the distinctive merits of Mn metal, in terms of high abundance, low cost, nontoxicity, high theoretical capacity and low redox potential. Conventional MIBs are based on the Mn²⁺ ion storage mechanism, whereas the capacity in cathode materials is generally limited due to the high charge density and large solvated ionic radius of Mn²⁺ ions in aqueous electrolytes. Herein, proton intercalation chemistry is introduced in aqueous MIBs, in which the layered Al_0.1 V₂ O₅ ⋅1.5 H₂ O (AlVO) cathode exhibits a consequent Mn²⁺ and H⁺ ion intercalation/extraction process. Such an energy storage mechanism contributes to enhanced electrochemical performance, including high capacity, fast reaction kinetics and stable cycling behavior. Benefiting from this proton intercalation chemistry, the aqueous Mn||AlVO cells could deliver high specific energy and power simultaneously. This work provides a route for the design of high-performance aqueous MIBs.

Solvation Effect on the Improved Sodium Storage Performance of N-Heteropentacenequinone for Sodium-Ion Batteries

The performance of electrode material is correlated with the choice of electrolyte, however, how the solvation has significant impact on electrochemical behavior is underdeveloped. Herein, N-heteropentacenequinone (TAPQ) is investigated to reveal the solvation effect on the performance of sodium-ion batteries in different electrolyte environment. TAPQ cycled in diglyme-based electrolyte exhibits superior electrochemical performance, but experiences a rapid capacity fading in carbonate-based electrolyte. The function of solvation effect is mainly embodied in two aspects: one is the stabilization of anion intermediate via the compatibility of electrode and electrolyte, the other is the interfacial electrochemical characteristics influenced by solvation sheath structure. By revealing the failure mechanism, this work presents an avenue for better understanding electrochemical behavior and enhancing performance from the angle of solvation effect.