The shuttle effect of aluminum polysulfides (AlPSs) have been a source of concern for studying Al/S batteries. Due to the weak adsorption of C-S composites, research on cathode materials for Al/S batteries has been delayed. As it is generally known that Al2S3 decomposition demands a large Gibbs free energy, this work has tried to reduce the Al2S3 decomposition potential energy. Herein, the Ni/Co bimetallic selenide reduces the energy barrier conversion and mitigates the polarization effects, while morphology control enables the storage and anchoring of S, alleviating the shuttle effect. Additionally, the intermediate products serve as single-atom catalysts, increasing the active sites, synergistically enhancing the ion diffusion kinetics. DFT calculations verify that NiCo2Se4 has a moderate Gibbs free energy change during the rate-limiting step of S reduction and the most robust adsorption energy to Al2S3. NiCo2Se4@CS2/Al has a remaining capacity of 135 mAh/g after 450 cycles (at 200 mA g(-1)), pioneering novel ideas for the development of Al/S batteries.

Aluminum batteries (ABs) are identified as one of the most promising candidates for the next generation of large-scale energy storage elements because of their efficient three-electron reaction. Compared to ionic electrolytes, aqueous aluminum-ion batteries (AAIBs) are considered safer, less costly, and more environmentally friendly. However, considerable cycling performance is a key issue limiting the development of AAIBs. Stable, efficient, and electrolyte-friendly cathodes are most desirable for AAIBs. Herein, a rod-shaped defect-rich alpha-MnO2 is designed as a cathode, which is capable to deliver high performance with stable cycling for 180 cycles at 500 mA g(-1) and maintains a discharge specific capacity of approximate to 100 mAh g(-1). In addition, the infiltrability simulation is effectively utilized to corroborate the rapid electrochemical reaction brought about by the defective mechanism. With the formation of oxygen vacancies, the dual embedding of protons and metal ions is activated. This work provides a brand-new design for the development and characterization of cathodes for AAIBs.

Aqueous aluminum-ion batteries (AAIBs) are considered a strong candidate for the new generation of energy storage devices. The lack of suitable cathode materials has been a bottleneck factor hindering the future development of AAIBs. In this work, we design and construct a highly effective cathode with dual morphologies. Two-dimensional (2D) layered MXene materials possessed good conductivity and hydrophilicity, which are used as the substrates to deposit rod-shaped vanadium oxides (V2O5) to form a three-dimensional (3D) cathode. The cathode design provides a strong boost for the rapid electrochemical activities of rod-shaped V2O5 by embedding/extracting both protons (H+) and aluminum-ion (Al3+). As a result, the V2O5@MXene cathode based AAIB delivers an ultrahigh initial specific capacity of 626 mAh/g at 0.1 A/g with a stable cycle performance up to 100 cycles. This work is a breakthrough for the development of cathode materials for AAIBs.

Aluminum-ion batteries have garnered an extensive amount of attention due to their superior electrochemical performance, low cost, and high safety. To address the limitation of battery performance, exploring new cathode materials and understanding the reaction mechanism for these batteries are of great significance. Among numerous candidates, multiple structures and valence states make manganese-based oxides the best choice for aqueous aluminum-ion batteries (AAIBs). In this work, a new cathode consists of γ-MnO2 with abundant oxygen vacancies. As a result, the electrode shows a high discharge capacity of 481.9 mAh g-1 at 0.2 A g-1 and a sustained reversible capacity of 128.6 mAh g-1 after 200 cycles at 0.4 A g-1. In particular, through density functional theory calculation and experimental comparison, the role of oxygen vacancies in accelerating the reaction kinetics of H+ has been verified. This study provides insights into the application of manganese dioxide materials in aqueous AAIBs.

In recent years, thanks to the excellent safety performance and extremely high theoretical specific capacity of rechargeable Al batteries, the development of Al battery cathode materials has become extremely competitive. In the structural design of cathode materials, the yolk-shell structure has a large amount of storage space and abundant active sites, giving full play to the advantages of synergy in building high-performance cathode structures. The construction of MoS2/NiS@S heterojunction interface effectively improves the conductivity of monometallic sulfide as cathode and improves the discharge performance of the electrode. The surface folds and pores of the heterojunction provide excellent channels for the free insertion and release of Al3+, reducing binding energy and enhancing Al3+ binding efficiency. It has maintained a reversible capacity of 130.19 mAh g-1 at 500 mA g-1 after 2000 cycles. This provides additional ideas for the development of transition metal sulfide materials in Al batteries.

The development of rechargeable aluminum batteries (RABs) has consistently relied on the logical selection and design of cathode materials. Se has a high electrical conductivity while S has a high theoretical specific capacity; yet, both materials are known to present lethal shuttle effects, space expansion, and slow reaction kinetics. The development of RABs will be accelerated if the synergistic properties of both materials can be utilized. Various ratios of SexSy as the cathode materials for RABs, and a series of electrochemical tests are shown in this work. The rise in the ratio of Se and S leads to the improvement of the cycling performance. However, the shuttle effect of Se and S has a fatal blow to the performance of the battery. To solve this problem, (mesostructured carbon materials) CMK3 modified separators were employed between the cathode and anode to further limit the dissolution of Se, considerably improving the utilization of the active materials. Therefore, initial capacity of Al/GF/C@CMK-3/SexSy is about 539.4 mAh g-1 and reversible ca-pacity of 314.2 mAh g-1 was likewise maintained after 500 cycles at 1.0 A g-1. RABs based on Al/S and Al/Se batteries have promising research avenues opened up by Al/SexSy batteries based on CMK3 modified se-parators.(c) 2023 Elsevier B.V. All rights reserved.

Selenides exhibit high energy density and long-cycle stability as aluminum-ion batteries cathode materials. It can provide a high number of electron transfer in the electrochemical reaction. Therefore, the selenides cathode material exhibits an outstanding initial specific capacity. Herein, one-dimensional Cu1.8Se nanofibers were prepared by electrospinning and high-temperature selenization. By changing the selenization temperature, Cu1.8Se-600, 800, 1000 were synthesized at 600, 800, and 1000 degrees C, respectively. Among them, Cu1.8Se-1000 has the highest crystallinity and the smallest grain size. High crystallinity means a high proportion of crystalline regions, and the crystal structure facilitates the intercalation/extraction of ions due to the ordered arrangement of molecules in three-dimensional space. Therefore, Cu1.8Se-1000 has an outstanding performance. Cu1.8Se-1000 exhibited the best electrochemical performance in the test: 152.12 mAh/g after 5000 cycles at 2.0 A/g. The obtained cathode material was assembled into a pouch battery, and the battery could still light up the diode in the folded state, which indicated the application prospect of this new cathode material in wearable devices.

As a favorable competitor of the next generation for large-scale energy storage components, aluminum batteries (ABs) have received attention from all walks of life. However, the air sensitivity and corrosiveness of nonaqueous electrolytes seriously hinder the further development of aluminum ion batteries (AIBs). ABs meet the needs of green development and become a key research object. An excellent performance is reflected in the energy storage system of Al/4 M Al(OTF)3+1M Ca(OTF)2(4Al+Ca)/AlxMnO2 & BULL;nH2O. It has an excellent discharge platform of 1.5 V, and can still maintain a high specific capacity of 233 mAh/g after 100 cycles. The cointercalation of metal ions and protons has been demonstrated by EELS and SSNMR. What is most interesting is that during discharging, Ca2+ has the dual function of balancing charge and supporting material. MnO undergoes in-situ electrochemical conversion during charging and combines with Al3+ to form AlxMnO2 & BULL;nH2O. In addition, the elaboration of the ion diffusion and solvation strategies inside the double-salt electrolyte is also an important exploration for the further development of aqueous aluminum batteries (AABs).

Aluminum is abundant and exhibits a high theoretical capacity and volumetric energy density. Additionally, the high safety of aqueous aluminum-ion batteries makes them strong candidates for large-scale energystorage systems. However, the frequent collapse of the cathode material and passive oxide film results in the difficult development of aqueous aluminum-ion batteries. This work provides a novel battery system, namely, Al-Zn/Al(OTF)3 +HOTF+Zn(OTF)2 /Alx Zny MnO2 ·nH2 O, with a mixed electrolyte. The cathode applies MnO topology transformation to ensure that the cathode forms Alx MnO2 ·nH2 O. Topology transformation alters the structure of the cathode material so that Zn2+ can be intercalated into the Alx MnO2 ·nH2 O spinel structure to provide support for the material structure. Regarding the anode, Zn2+ in the electrolyte is deposited onto Al of the anode to produce a regional Al-Zn alloy. Zn2+ is reduced to Zn metal during discharging, which adds a platform for secondary discharge beneficial for battery capacity enhancement. This system can provide a 1.6 V discharge platform, while the first cycle discharge can reach 554 mAh g-1 , thereby maintaining a high capacity of 313 mAh g-1 after 100 cycles. This study provides a new idea for the further development of aqueous aluminum-ion batteries (AAIBs).

Although the cathode materials of aluminum batteries have been extensively valued, their further development has encountered bottlenecks due to their low discharge capacity and low working voltage platform. In this study, we successfully prepare carbon-coated hollow nanocube ZnSe (ZnSe@C) by the selenization process of the zeolitic imidazolate framework (ZIF-67). The energy storage mechanism is found by X-ray photoelectron spectroscopy (XPS) and electrochemical analysis that the reversible reaction Se2-/Sex+ in ZnSe@C can be carried out during the electrochemical cycles. Moreover, the first and second capacities of ZnSe@C are 396.2 and 472.6 mA h g(-1) at 0.2 A g(-1), respectively. After 100 cycles, the capacity is still as high as 197.1 mA h g(-1) at 0.5 A g(-1). In addition, the working voltage (1.8 V) is much higher than the other cathode material of aluminum batteries such as oxides, sulfides, and phosphides. Therefore, it is obvious that the carbon-coated ZnSe constructed by ZIF-67 is beneficial to the research for aluminum batteries. (C) 2022 Elsevier B.V. All rights reserved.

Transition metal selenides have shown outstanding performance as cathode materials for aluminum-ion batteries and have thus become a popular choice for cathode materials. Herein, Mn-based carbon fibers (Mn/CNFs) were first synthesized by electrospinning as a precursor, and then MnSe composites were prepared by a melt-diffusion method. However, due to polyselenides and selenides being generated during electrochemical reactions, the cycling stability of MnSe cathode materials is poor. After 200 cycles, the discharge specific capacity is only 176 mA h/g. To suppress the shuttle effect of selenides and polyselenides, a CMK-3-modified separator was used instead of a glass fiber separator. Compared with MnSe-800, the replaced MnSe-800/CMK-3 has a great capacity improvement; the initial discharge specific capacity is 1029.85 mA h/g, which after 3000 cycles, still remains at 297.84 mA h/g. The soft pack battery can still light up the LED normally under different degrees of folding, which proves the application of this material in wearable devices. This work provides a new way to improve the performance of transition metal selenides.