Aqueous Al-ion Batteries Research Articles

High-performance aqueous Al-ion batteries

Electrochemistry Because of its high abundance, low production cost, and three-electron redox properties, aluminum (Al) has received considerable attention in recent years for the development of possible alternatives to conventional lithium-based batteries. Yan et al. propose an aqueous Al-ion battery configuration consisting of an Al x MnO2 cathode, a zinc substrate–supported Zn-Al alloy anode, and an Al(OTF)3 aqueous electrolyte. This battery demonstrates promising values for key performance indicators such as cycling life, reversible capacity, discharge voltage plateau, and rate capability. The present work is an important step in designing Al-ion–based batteries for practical applications. J. Am. Chem. Soc. 10.1021/jacs.0c05054 (2020).

Nanomanufacturing of RGO-CNT Hybrid Film for Flexible Aqueous Al-Ion Batteries.

A highly electrically conductive film-type current collector is an essential part of batteries. Apart from the metal-based current collectors, lightweight and highly conductive carbon materials such as reduced graphene oxide (RGO) and carbon nanotubes (CNTs) show great potential as current collectors. However, traditional RGO manufacturing usually requires a long time and high energy, which decreases the product yielding rate and manufacturing efficiency. Moreover, the performance of the manufactured RGO needs to be further improved. In this work, CNT and GO are evenly mixed into GO-CNT, which can be directly reduced into RGO-CNT by Joule heating at 2936 K within less than 1 min. The fabricated RGO-CNT achieves a high electrical conductivity of 2750 S cm-1 , and realizes a 106 -fold increase. The assembled flexible aqueous Al-ion battery with RGO-CNT as the current collector exhibits impressive electrochemical performance in terms of superior cycling stability and exceptional rate capability, and excellent mechanical ability regarding the tolerance to mechanical damage such as bending, folding, piercing, and cutting without detrimental consequences.

Architecting a Stable High-Energy Aqueous Al-Ion Battery.

Aqueous Al-ion batteries (AAIBs) are the subject of great interest due to the inherent safety and high theoretical capacity of aluminum. The high abundancy and easy accessibility of aluminum raw materials further make AAIBs appealing for grid-scale energy storage. However, the passivating oxide film formation and hydrogen side reactions at the aluminum anode as well as limited availability of the cathode lead to low discharge voltage and poor cycling stability. Here, we proposed a new AAIB system consisting of an AlxMnO2 cathode, a zinc substrate-supported Zn-Al alloy anode, and an Al(OTF)3 aqueous electrolyte. Through the in situ electrochemical activation of MnO, the cathode was synthesized to incorporate a two-electron reaction, thus enabling its high theoretical capacity. The anode was realized by a simple deposition process of Al3+ onto Zn foil substrate. The featured alloy interface layer can effectively alleviate the passivation and suppress the dendrite growth, ensuring ultralong-term stable aluminum stripping/plating. The architected cell delivers a record-high discharge voltage plateau near 1.6 V and specific capacity of 460 mAh g-1 for over 80 cycles. This work provides new opportunities for the development of high-performance and low-cost AAIBs for practical applications.

An Aqueous Al-Ion Battery Boosted by Triple-Ion Intercalation Chemistry with a High-Energy MnAl <sub>2</sub>O <sub>4</sub> Nanosphere Cathode

AlCl3 water-in-salt electrolyte has successfully expanded the electrochemical window of aqueous Al-ion battery to 4 volts, however, the limited Al intercalation capacity of graphite (165 mAh g-1 ) preclude higher energy density. A high-energy MnAl2O4 cathode was synthesized by a simple two-step hydrothermal method, which can utilize triple-ion intercalation chemistry to achieve a high specific capacity of 330 mAh g-1 with an average discharge voltage of 1.68V versus Al/Al3+ (a record energy density of 555 Wh kg-1 ). Besides, a higher discharge capacity of 830 Wh kg-1 was achieved with higher-concentration electrolyte, showing a potential capacity for cation intercalation. Unique triple-ion intercalation chemistry was firstly investigated thoroughly. Experimental characterization attributes this high voltage to the intercalation of anions, e.g., AlCl4- and Cl- , and Cl- was also revealed an interaction function with intercalated Al3+ cations, which can benefit the design of Aluminium-ion batteries (AIBs) in the future.

Water-in-Salt Electrolyte Promotes High-Capacity FeFe(CN)6 Cathode for Aqueous Al-Ion Battery.

Prussian blue analogues (PBAs) are considered to be ideal multivalent cation host materials due to their unique open-framework structure. In aqueous solution, however, the PBAs' cathodes have a low reversible capacity limited by the single electrochemical group Fe(CN)63- and high crystal water content. They also suffer from fast cycle fading, resulting from significant oxygen/hydrogen evolution and cathode dissolution. In this work, a high-capacity PBA-type FeFe(CN)6 cathode with double transition metal redox sites is successfully demonstrated in 5 m Al(CF3SO3)3 Water-in-Salt electrolyte (Al-WISE). Due to Al-WISE having a wide electrochemical window (2.65 V) and low dissolution of the cathode, our PBA cathode exhibits a high discharge capacity of 116 mAh/g and the superior cycle stability >100 cycles with capacity fading of 0.39% per cycle.

Hierarchically hybrid nanostructure of carbon nanoparticles decorated graphene sheets as an efficient electrode material for supercapacitors, aqueous Al-ion battery and capacitive deionization

A facile and rapid candle flame treatment technique has been developed to synthesize the hybrid nanostructure of soot-based carbon nanoparticles decorated graphene sheets (CN-GS) from graphene oxide. In this technique, candle flame serves the dual purpose i.e. acting as reducing medium for the graphene oxide reduction into graphene and it also acts as a source of carbon nanoparticles. During the flame treatment, these nanoparticles get uniformly deposited on the graphene sheets. The as-prepared nanocomposite has been characterized thoroughly and studied as an electrode material for supercapacitors, aqueous Al-ion battery and capacitive deionization (CDI) applications. The CN-GS based symmetric supercapacitor device exhibits an excellent gravimetric specific capacitance of 351 F g−1 and energy density of 12.2 Wh kg−1. The electrochemical performance of this material has also been tested for the aqueous Al-ion battery cathode, where it was found to possess 152.7 mAh g−1 of specific capacity. In addition to this, CN-GS based CDI electrode exhibited the salt adsorption capacity of 30.7 mg g−1. The CN-GS should be a promising electrode material for highly efficient energy storage devices and CDI applications due to its excellent electrochemical performance and long cyclic stability.

Reversible Intercalation of Multivalent Al3+ Ions into Potassium-Rich Cryptomelane Nanowires for Aqueous Rechargeable Al-Ion Batteries.

The development of new battery technology that utilizes abundant electrode materials that are environmentally benign is an important area of research. To alleviate the reliance on Li-ion batteries new energy storage mechanisms are urgently needed. To address these issues, MnO2 nanowires were investigated as a possible electrode material for use in rechargeable Al ion batteries that can operate in aqueous conditions. The use of this type of material and an aqueous electrolyte ensures safe operation as well as easy recycling of spent batteries. A potassium-rich cryptomelane structure was presented, and a new mechanism of electrochemical energy storage was elucidated based on the intercalation and deintercalation of small-radius Al3+ ions interchanging with larger K+ ions in the cryptomelane MnO2 nanowires, which was supported by DFT calculations. This first-time use of a cryptomelane MnO2 cathode for an aqueous Al ion system yielded a discharge capacity of 109 mAh g-1 , which indicates the potential commercial viability of rechargeable aqueous Al-ion batteries.

A flexible aqueous Al ion rechargeable full battery

With the fast development of flexible and wearable electronics, the design of secondary energy storage system based on aqueous metal ion battery with outstanding flexibility, safety and low cost is critical for their practical application. As low-cost alternatives to lithium ion battery, multivalent metal ion technologies including Mg2+, Zn2+, Ca2+, and Al3+ are investigated increasingly in the past few years. The investigation based on Al-ion chemistry is also underway considering the aluminum’s advantages of natural abundance, small ion size together with three-electron-redox properties. Herein, a flexible aqueous Al-ion battery is successfully fabricated for the first time with copper hexacyanoferrate cathode and polypyrrole (PPy) coated MoO3 anode sandwiched by gel electrolyte. The as-assembled Al-ion battery based on intercalation chemistry exhibits an excellent cycling stability of 83.2% capacity retention after 100 cycles and good rate capability benefiting from the conductive PPy coating layer on MoO3 anode. Besides, the battery demonstrates impressive flexibility and safety to sustain various deformations and mechanical abuse including bending, squeezing, folding, twisting as well as arbitrary drilling and tailoring into any desired shapes. Obviously, the flexible aqueous Al-ion battery developed in this study paves the way of multivalent metal ion battery as energy storage device towards various wearable electronics.

Oxygen-Rich Hierarchical Porous Graphene as an Excellent Electrode for Supercapacitors, Aqueous Al-Ion Battery, and Capacitive Deionization

In this study, we have described the synthesis of oxygen-rich hierarchical porous graphene (O-PG) using focused solar radiation on nitric acid treated graphene oxide film. This nitric acid treatment for graphene oxide helps in generating micropores on the graphene sheets and introducing oxygen-containing functional groups when solar light is focused. This unique hierarchical porous structure along with high surface area and oxygenated functional groups makes O-PG as suitable electrode in energy storage and also for capacitive deionization. The as-prepared O-PG exhibits high specific capacitance of 354 F g–1 along with energy storage of 110.6 Wh kg–1 at 1 A g–1 current density. O-PG also delivers high specific capacity of 90 mAh g–1 as high-performance cathode in aqueous Al-ion battery with an exceptionally high cyclic stability up to 10 000 cycles of charging–discharging processes at high current density of 0.5 A g–1. In addition, the electrosorption studies of salt ions were done using capacitive deioniz...

Expression of concern: Black mesoporous anatase TiO2 nanoleaves: a high capacity and high rate anode for aqueous Al-ion batteries

Expression of concern for ‘Black mesoporous anatase TiO2 nanoleaves: a high capacity and high rate anode for aqueous Al-ion batteries’ by Ying Juan He et al., J. Mater. Chem. A, 2014, 2, 1721–1731.

Retraction: Black mesoporous anatase TiO2 nanoleaves: a high capacity and high rate anode for aqueous Al-ion batteries

Retraction of ‘Black mesoporous anatase TiO2 nanoleaves: a high capacity and high rate anode for aqueous Al-ion batteries’ by Ying Juan He et al., J. Mater. Chem. A, 2014, 2, 1721–1731.

Electrochemically Treated TiO₂ for Enhanced Performance in Aqueous Al-Ion Batteries.

The potential for low cost, environmentally friendly and high rate energy storage has led to the study of anatase-TiO2 as an electrode material in aqueous Al3+ electrolytes. This paper describes the improved performance from an electrochemically treated composite TiO2 electrode for use in aqueous Al-ion batteries. After application of the cathodic electrochemical treatment in 1 mol/dm3 KOH, Mott–Schottky analysis showed the treated electrode as having an increased electron density and an altered open circuit potential, which remained stable throughout cycling. The cathodic treatment also resulted in a change in colour of TiO2. Treated-TiO2 demonstrated improved capacity, coulombic efficiency and stability when galvanostatically cycled in 1 mol·dm−3AlCl3/1 mol·dm−3 KCl. A treated-TiO2 electrode produced a capacity of 15.3 mA·h·g−1 with 99.95% coulombic efficiency at the high specific current of 10 A/g. Additionally, X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy were employed to elucidate the origin of this improved performance.

High surface area TiO2 nanospheres as a high-rate anode material for aqueous aluminium-ion batteries

Aluminium-ion batteries are promising electrochemical energy storage systems in replacement of Li-ion batteries owing to the low cost, non-toxicity, safety and three-electron transfer nature of Al-intercalation process. Anatase titanium dioxide has been suggested as a potential anode material for aqueous Al-ion batteries. In this work, TiO2 nanospheres (TiO2-NSs) with highly mesoporous morphology and large specific surface area (179.9m2g−1) were synthesized via hydrolysis of titanium glycolate precursor and subsequent hydrothermal treatment and calcination in an argon atmosphere. The structure and morphology of the prepared TiO2-NSs were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy and nitrogen adsorption-desorption. The high surface area TiO2-NSs provide large electrode/electrolyte interface and good electrolyte-holding characteristic, leading to shorten the diffusion path of electrons and ions to the active material, which results in the better high-rate performance. The TiO2-NSs anode exhibited a high initial discharge capacity of 183mAhg−1 at a current rate of 0.15C and a superior rate performance with a capacity of 108mAhg−1 even at a discharge current rate of 6.0C, which are much higher than those of TiO2-P25 electrode.

Copper hexacyanoferrate nanoparticles as cathode material for aqueous Al-ion batteries

Copper hexacyanoferrate (CuHCF) nanoparticles with Prussian blue structure present the ability to insert Al ions reversibly in aqueous solution.