Design Strategies of High-Performance Positive Materials for Nonaqueous Rechargeable Aluminum Batteries: From Crystal Control to Battery Configuration

A Non-Flammable and Flexible Aluminum Derived Lithium-Ion Storage Device with a Wide Temperature Range of Operation

With the rapid development and increasing popularity of electric vehicles and wearables, battery safety has become a leading focus in the field of energy storage research. Specifically, aluminum-ion batteries are gaining increasing attention as low-cost energy-storage systems with high safety levels and theoretical energy density. However, the dense alumina passivation layer on the aluminum anode surface and slow kinetic performance of commonly used ionic liquid electrolytes still render poor performance. This report presents a new type of aluminum-derived lithium-ion battery (ALIB) that maintains a certain discharge performance under damaging conditions, including continuous bending, high- and low-temperature environments, and shearing. This new ALIB effectively meets the current demand for flexible and wearable batteries. The prepared ALIB achieves a stable cycle of 130 mAh g-1 specific capacity and ≈260 Wh kg-1 theoretical energy density at a wide voltage platform of 2 V and a test temperature of 25 °C without undergoing combustion. Additionally, the study analyzes the reaction mechanism of this ALIB based on density functional theory and conducts ex situ XRD and XPS analyses to elucidate the underlying storage mechanism.

Enhancing Electrochemical Performance of Aluminum-Oxygen Batteries with Graphene Aerogel Cathode

Aluminum-oxygen batteries (AOBs) own the benefits of high energy density (8.14 kWh kg-1 ), low cost, and high safety. However, the design of a cathode with high surface area, structure integrity, and good catalytic performance is still challenging for rechargeable AOBs. Herein, the fabrication of a robust self-supporting cathode using 3D graphene aerogel (3DGA) for rechargeable AOBs is demonstrated. Electroanalysis showed that the 3DGA presented good catalytic activity in both oxygen reduction and evolution reactions, which allowed the AOB to operate for >90 cycles with low overpotentials at a current density of 0.2 mA cm-2 , and a high Coulombic efficiency of ca. 99% using ionic liquid as electrolyte. In comparison, the cell with the carbon paper cathode can only cycle for 50 rounds. The excellent cyclic performance can be attributed to the porous structure, large surface area, good electric conductivity, and catalytic activity of the 3DGA, which is prospective to be applied for other metal-air batteries, fuel cells, and supercapacitors.

High-performance MnSe2-MnSe heterojunction hollow sphere for aluminum ion battery

With its consistent thermal runaway temperature and superior capacity, aluminum ion batteries have emerged as a key area for battery development. At the moment, electrode material is the main focus of aluminum ion battery capacity enhancement. Selenide is anticipated to develop into a high-performance cathode for aluminum ion batteries, since it is a type of high energy density electrode material. However, because selenide is soluble in acid electrolytes, Al-Se batteries have low cycle performance and cannot keep up with the present demand for electronic gadgets. Here, homogeneous-structured precursors were created via a hydrothermal reaction, and MnSe2-MnSe heterojunction hollow spheres were created a step further via temperature control of the selenidation reaction. With 103.76 mAh/g of specific capacity remaining after 3000 cycles at 1.0 A/g, this novel heterojunction material exhibits astounding cycle stability. After additional investigation, it was shown that the MnSe2-MnSe heterojunction may prevent the dispersion of the active substances, significantly enhancing the cycle performance. The density of states (DOS) of electrode materials demonstrates the superior electronic conductivity of this heterojunction material. Meanwhile, it was computationally demonstrated that the MnSe2-MnSe heterojunction has a strong adsorption energy for AlCl4-, thus accelerating the reaction kinetics. In summary, the performance of selenides has been improved by this novel heterojunction material, which also makes for a superior cathode material.

Selection principles of polymeric frameworks for solid-state electrolytes of non-aqueous aluminum-ion batteries

Liquid electrolyte systems of aluminum-ion batteries (AIBs) have restrictive issues, such as high moisture sensitivity, strong corrosiveness, and battery leakage, so researchers have turned their attention to developing high safety, leak-free polymer electrolytes. However, the stability of the active factor of AIB systems is difficult to maintain with most of polymeric frameworks due to the special Al complex ion balance in chloroaluminate salts. Based on this, this work clarified the feasibility and specific mechanism of using polymers containing functional groups with lone pair electrons as frameworks of solid-state electrolytes for AIBs. As for the polymers reacting unfavorably with AlCl₃, they cannot be used as the frameworks directly due to the decrease or even disappearance of chloroaluminate complex ions. In contrast, a class of polymers represented by polyacrylamide (PAM) can interact with AlCl₃ and provide ligands, which not only have no effect on the activity of Al species but also provide chloroaluminate complex ions through complexation reactions. According to DFT calculations, amide groups tend to coordinates with AlCl₂ ⁺ via O atoms to form [AlCl₂(AM)₂]⁺ cations, while disassociating chloroaluminate anions. Furthermore, the PAM-based solid-state and quasi-solid-state gel polymer electrolytes were also prepared to investigate their electrochemical properties. This work is expected to provide new theoretical and practical directions for the further development of polymer electrolytes for AIBs.