One-Dimensional Cu2- xSe Nanorods as the Cathode Material for High-Performance Aluminum-Ion Battery

Research Advances of Cathode Materials for Rechargeable Aluminum Batteries

Rechargeable aluminum ion batteries (AIBs) have recently gained widespread research concern as energy storage technologies because of their advantages of being safe, economical, environmentally friendly, sustainable, and displaying high performance. Nevertheless, the intense Coulombic interactions between the Al3+ ions with high charge density and the lattice of the electrode body lead to poor cathode kinetics and limited cycle life in AIBs. This paper reviews the recent advances in the cathode design of AIBs to gain a comprehensive understanding of the opportunities and challenges presented by current AIBs. In addition, the advantages, limitations, and possible solutions of each cathode material are discussed. Finally, the future development prospect of the cathode materials is presented.

Ultrahigh Capacity from Complexation-Enabled Aluminum-Ion Batteries with C70 as the Cathode

Restricted by the available energy storage modes, currently rechargeable aluminum-ion batteries (RABs) can only provide a very limited experimental capacity, regardless of the very high gravimetric capacity of Al (2980 mAh g-1 ). Here, a novel complexation mechanism is reported for energy storage in RABs by utilizing 0D fullerene C70 as the cathode. This mechanism enables remarkable discharge voltage (≈1.65 V) and especially a record-high reversible specific capacity (750 mAh g-1 at 200 mA g-1 ) of RABs. By means of in situ Raman monitoring, mass spectrometry, and density functional theory (DFT) calculations, it is found that this elevated capacity is attributed to the direct complexation of one C70 molecule with 23.5 (super)halogen moieties (superhalogen AlCl4 and/or halogen Cl) in average, forming (super)halogenated C70 ·(AlCl4 )m Cln-m complexes. Upon discharging, decomplexation of C70 ·(AlCl4 )m Cln-m releases AlCl4 - /Cl- ions while preserving the intact fullerene cage. This work provides a new route to realize high-capacity and long-life batteries following the complexation mechanism.

Advances of Zn Metal-Free "Rocking-Chair"-Type Zinc Ion Batteries: Recent Developments and Future Perspectives

Aqueous zinc ion battery (AZIBs) has attracted the attention of many researchers because of its safety, economy, environmental protection, and high ionic conductivity of electrolytes. However, the battery greatly suffers from zinc dendrite produced by zinc metal anode leading to poor cycle life and even unsafe problems, which limit its further development for various important applications. It is known that the success of the commercialization of lithium-ion batteries (LIBs) is mainly due to replacement of lithium metal anode with graphite, which avoids the formation of Li dendrite. Therefore, it is an important step to develop aqueous zinc ion anode to replace conventional zinc metal one with zinc-metal free anode material. In this review, the working principle and development prospect of "rocking-chair" AZIBs are introduced. The research progress of different types of zinc metal-free anode materials and cathode materials in "rocking-chair" AZIBs is reviewed. Finally, the limitations and challenges of the Zn metal-free "rocking-chair" AZIBs as well as solutions are deeply discussed, aiming to provide new strategies for the development of advanced zinc-ion batteries.

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.

Effects of Multiple Ion Reactions Based on a CoSe2 /MXene Cathode in Aluminum-Ion Batteries

Rechargeable aluminum-ion batteries (RAIBs) have emerged as a promising battery storage technology owing to their cost-effectiveness, operational safety, and high energy density. However, their actual capacity is substantially lower than their true capacity and their cycling stability is poor. Therefore, understanding the energy-storage mechanism may contribute to the successful design of a stable electrode material, on which the performance can be optimized. The aim of this study is to investigate AlCl₄ ^- ions in transition metal cathode materials and mechanisms that enable for their high-energy-storage potential and low Coulombic efficiency. Results of theoretical analysis and experimental verification show that a multi-ion transport mechanism is responsible for the electrochemical behavior of the battery. The lattice distortion of CoSe₂ caused by AlCl₄ ^- ion intercalation, has a considerable effect on the initial stability of the battery. MXene as a support material reduces the size of CoSe₂ growing on its surface, effectively inhibiting the lattice distortion caused by the interaction with the aluminum-anion complex, thus addressing the issues of poor reversibility, cycle instability, and low Coulombic efficiency of the battery. Hence, understanding the impact of MXene on the battery may aid in further improving the design of electrode materials.

One-Pot Synthesis of NiSe2 with Layered Structure for Nickel-Zinc Battery

Transition metal organic framework materials and their selenides are considered to be one of the most promising cathode materials for nickel-zinc (denoted as Ni-Zn) batteries due to their low cost, environmental friendliness, and controllable microstructure. Yet, their low capacity and poor cycling performance severely restricts their further development. Herein, we developed a simple one-pot hydrothermal process to directly synthesize NiSe₂ (denotes as NiSe₂-X based on the molar amount of SeO₂ added) stacked layered sheets. Benefiting from the peculiar architectures, the fabricated NiSe₂-1//Zn battery based on NiSe₂ and the Zn plate exhibits a high specific capacity of 231.6 mAh g^-1 at 1 A g^-1, and excellent rate performance (162.8 mAh g^-1 at 10 A g^-1). In addition, the NiSe₂//Zn battery also presents a satisfactory cycle life at the high current density of 8 A g^-1 (almost no decay compared to the initial specific capacity after 1000 cycles). Additionally, the battery device also exhibits a satisfactory energy density of 343.2 Wh kg^-1 and a peak power density of 11.7 kW kg^-1. This work provides a simple attempt to design a high-performance layered cathode material for aqueous Ni-Zn batteries.

Fe2(MoO4)3 assembled by cross-stacking of porous nanosheets enables a high-performance aluminum-ion battery

Rechargeable aluminum-ion batteries have attracted increasing attention owing to the advantageous multivalent ion storage mechanism thus high theoretical capacity as well as inherent safety and low cost of using aluminum. However, their development has been largely impeded by the lack of suitable positive electrodes to provide both sufficient energy density and satisfactory rate capability. Here we report a candidate positive electrode based on ternary metal oxides, Fe2(MoO4)3, which was assembled by cross-stacking of porous nanosheets, featuring superior rate performance and cycle stability, and most importantly a well-defined discharge voltage plateau near 1.9 V. Specifically, the positive electrode is able to deliver reversible capacities of 239.3 mA h g-1 at 0.2 A g-1 and 73.4 mA h g-1 at 8.0 A g-1, and retains 126.5 mA h g-1 at 1.0 A g-1 impressively, after 2000 cycles. Furthermore, the aluminum-storage mechanism operating on Al3+ intercalation in this positive electrode is demonstrated for the first time via combined in situ and ex situ characterization studies and density functional theory calculations. This work not only explores potential positive electrodes for aluminum-based batteries but also sheds light on the fundamental charge storage mechanism within the electrode.

Dual Protection Strategy by Constructing MXene-Coated Cu2Se-Cu1.8Se Heterojunction and CMK-3 Modification for High-Performance Aluminum-Ion Batteries

The fabrication of cathode materials with ideal kinetic behavior is important to improve the electrochemical performance of aluminum-ion batteries (AIBs). Transition metal selenides have the advantages of abundant reserves and high discharge specific capacity and discharge voltage plateau, which makes them a promising material for rechargeable AIBs. It is well-known that the low structural stability and relatively poor reaction kinetics pose a considerable challenge to the development of AIBs. The cubic structure of Cu₂Se-Cu_1.8Se can adapt to the volume change of the active material during cycling and facilitate the intercalation and deintercalation of chloroaluminate anions in the cathode material. We created a two-fold protection mechanism for AIBs with a CMK-3 modified separator and a Cu₂Se-Cu_1.8Se heterojunction coated with MXene in order to better mitigate the detrimental impacts. In addition to offering numerous electronic transmission routes, MXene and CMK-3 help prevent the solubilization of active species. This novel design enables the Cu₂Se-Cu_1.8Se@MXene composite to have a high initial discharge capacity of 705.5 mAh g^-1 at 1.0 A g^-1. Even after 1500 cycles at 2.0 A g^-1, the capacity is still maintained at 225.1 mAh g^-1. Furthermore, the reaction mechanism of AlCl₄^- intercalated/deintercalated into Cu₂Se-Cu_1.8Se heterojunction is revealed during charge/discharge. This work to construct novel cathode materials has greatly improved the electrochemical performance of AIBs.

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

Rechargeable aluminum batteries (RABs) have been paid considerable attention in the field of electrochemical energy storage batteries due to their advantages of low cost, good safety, high capacity, long cycle life, and good wide-temperature performance. Unlike traditional single-ion rocking chair batteries, more than two kinds of active ions are electrochemically participated in the reaction processes on the positive and negative electrodes for nonaqueous RABs, so the reaction kinetics and battery electrochemistries need to be given more comprehensive assessments. In addition, although nonaqueous RABs have made significant breakthroughs in recent years, they are still facing great challenges in insufficient reaction kinetics, low energy density, and serious capacity attenuation. Here, the research progresses of positive materials are comprehensively summarized, including carbonaceous materials, oxides, elemental S/Se/Te and chalcogenides, as well as organic materials. Later, different modification strategies are discussed to improve the reaction kinetics and battery performance, including crystal structure control, morphology and architecture regulation, as well as flexible design. Finally, in view of the current research challenges faced by nonaqueous RABs, the future development trend is proposed. More importantly, it is expected to gain key insights into the development of high-performance positive materials for nonaqueous RABs to meet practical energy storage requirements.

Alternate Storage of Opposite Charges in Multisites for High-Energy-Density Al-MOF Batteries

The limited active sites of cathode materials in aluminum-ion batteries restrict the storage of more large-sized Al-complex ions, leading to a low celling of theoretical capacity. To make the utmost of active sites, an alternate storage mechanism of opposite charges (AlCl₄ ^- anions and AlCl₂ ⁺ cations) in multisites is proposed herein to achieve an ultrahigh capacity in Al-metal-organic framework (MOF) battery. The bipolar ligands (oxidized from 18π to 16π electrons and reduced from 18π to 20π electrons in a planar cyclic conjugated system) can alternately uptake and release AlCl₄ ^- anions and AlCl₂ ⁺ cations in charge/discharge processes, which can double the capacity of unipolar ligands. Moreover, the high-density active Cu sites (Cu nodes) in the 2D Cu-based MOF can also store AlCl₂ ⁺ cations for a higher capacity. The rigid and extended MOF structure can address the problems of high solubility and poor stability of small organic molecules. As a result, three-step redox reactions with two-electron transfer in each step are demonstrated in charge/discharge processes, achieving high reversible capacity (184 mAh g^-1 ) and energy density (177 Wh kg^-1 ) of the optimized cathode in an Al-MOF battery. The findings provide a new insight for the rational design of stable high-energy Al-MOF batteries.

Constructing NiCo2Se4/NiCoS4 heterostructures for high-performance rechargeable aluminum battery cathodes

An aluminum battery based on the NiCo2Se4/NiCoS4 cathode delivers a capacity of 112 mA h g−1 after 195 cycles. The charge–discharge principle of the NiCo2Se4/NiCoS4 cathode is the Al3+ intercalation and valence state transition of the Ni, Co, and S elements.

Tailored Chiral Copper Selenide Nanochannels for Ultrasensitive Enantioselective Recognition and Detection

We constructed a tailorable membrane channel system consisting of penicillamine molecules intercalated in copper selenide nanoparticles (Cu_2-x Se NPs), which exhibited circular dichroism (CD) bands in the near infrared region (CD, 800-1600 nm) with a maximum intensity of 164.5 mdeg at 1440 nm. The chiral ligand hybridized to the surface of achiral Cu_2-x Se NPs by breaking the intrinsic symmetry of Cu_2-x Se NPs and further large-scale assembly induced strong optical activity. The fabricated multilayer chiral membrane achieved an increased rectification ratio (RR) up to 114. The integration of penicillamine allowed for high enantioselective recognition against naproxen,which displayed high sensitivity with a limit of detection (LOD) as low as 0.027 nM.

A facile synthesis of Ni0.85Se@Cu2-xSe nanorods as high-performance supercapacitor electrode materials

Transition-metal selenides are regarded as promising electrode materials due to their superior electrochemical performances for supercapacitors. In this study, a nanorod-like hybrid of Ni_0.85Se@Cu_2-xSe on a Ni-foam substrate is successfully synthesized via a facile one-step route. The Ni_0.85Se@Cu_2-xSe nanorods are found to be deposited uniformly on the Ni-form substrates. When used as a battery-type electrode in a supercapacitor, the as-deposited Ni_0.85Se@Cu_2-xSe electrode exhibits a high specific capacity of 1831 F g^-1 at 1 A g^-1 and 78.4% of capacitance retention after 8000 cycles at 10 A g^-1. Moreover, the assembled Ni_0.85Se@Cu_2-xSe//AC asymmetric supercapacitor (ASC) exhibits an energy density of 63.2 W h kg^-1 at a power density of 800.1 W kg^-1, as well as good cycling stability (92.1% capacitance retention after 5000 cycles).

High-Performance MnO2 /Al Battery with In Situ Electrochemically Reformed Alx MnO2 Nanosphere Cathode

Aqueous Al-ion battery (AAIB) is regarded as a promising candidate for large-scale energy storage systems due to its high capacity, high safety, and low cost, with MnO₂ proved to be a high-performance cathode. However, the potential commercial application of this type of battery is plagued by the frequent structural collapse of MnO₂ . Herein, an in situ, electrochemically reformed, urchin-like Al_x MnO₂ cathode is developed for water-in-salt electrolyte-based AAIBs. Benefiting from its unique α-MnO₂ coated Mn₂ AlO₄ structure, a high Al ion storage capacity is achieved together with a high discharge voltage plateau of 1.9 V by reversible MnO₂ electrolysis. Consequently, the battery exhibits a high specific capacity of 285 mAh g^-1 and a high energy density of 370 Wh kg^-1 at a high current density of 500 mA g^-1 . Improved stability with record capacity retention is also obtained at an ultrahigh current density of 5 A g^-1 after 500 cycles. Such a high-capacity and high-stability Al_x MnO₂ cathode would pave the way for in situ electrochemical transformation of cathode design and thus boost the practical application of AAIBs.

A cobalt-based metal-organic framework and its derived material as sulfur hosts for aluminum-sulfur batteries with the chemical anchoring effect

With the urgent need to explore high-performance electrochemical energy storage systems, rechargeable Al-ion batteries (AIBs) have attracted attention from researchers and engineers due to their traits, such as abundance and safety. Among all the issues waiting to be solved, the development of a reliable positive electrode material with high specific capacity is an absolute priority for the commercialization of AIBs. Sulfur has a natural advantage when used as the active material, and its theoretical specific capacity is as high as 1675 mA h g-1. MOFs and MOF-derived materials have been proved to be promising hosts for Li-S batteries. Herein, we report a novel Al-S battery system employing MOF (ZIF-67) and MOF-derived materials as sulfur host materials. After being chemically combined with sulfur, the composite still maintains its unique well-defined polyhedron morphology. The voltage hysteresis phenomenon is effectively alleviated with the aid of the host matrix. DFT calculations confirm that ZIF-67 and carbonized ZIF-67-700 polyhedrons can act as an anchor point towards sulfur (S8) and polysulfides (Al2S3, Al2S6, Al2S12, and Al2S18), preventing the detrimental dissolution and shuttle effect. These findings can enlighten future researchers regarding Al-S batteries and broaden the application of MOFs in the field of electrochemical energy storage systems.

Tetradiketone macrocycle for divalent aluminium ion batteries

Contrary to early motivation, the majority of aluminium ion batteries developed to date do not utilise multivalent ion storage; rather, these batteries rely on monovalent complex ions for their main redox reaction. This limitation is somewhat frustrating because the innate advantages of metallic aluminium such as its low cost and high air stability cannot be fully taken advantage of. Here, we report a tetradiketone macrocycle as an aluminium ion battery cathode material that reversibly reacts with divalent (AlCl²⁺) ions and consequently achieves a high specific capacity of 350 mAh g⁻¹ along with a lifetime of 8000 cycles. The preferred storage of divalent ions over their competing monovalent counterparts can be explained by the relatively unstable discharge state when using monovalent AlCl₂⁺ ions, which exert a moderate resonance effect to stabilise the structure. This study opens an avenue to realise truly multivalent aluminium ion batteries based on organic active materials, by tuning the relative stability of discharged states with carrier ions of different valence states.

Aluminium ion batteries have been developed based on the storage of monovalent complex ions, impairing their original motivation of storing multivalent ions. Here, the authors demonstrate the divalent ion storage of tetradiketone macrocycles by tuning the relative stability of discharged states.

Nonaqueous Rechargeable Aluminum Batteries: Progresses, Challenges, and Perspectives

For significantly increasing the energy densities to satisfy the growing demands, new battery materials and electrochemical chemistry beyond conventional rocking-chair based Li-ion batteries should be developed urgently. Rechargeable aluminum batteries (RABs) with the features of low cost, high safety, easy fabrication, environmental friendliness, and long cycling life have gained increasing attention. Although there are pronounced advantages of utilizing earth-abundant Al metals as negative electrodes for high energy density, such RAB technologies are still in the preliminary stage and considerable efforts will be made to further promote the fundamental and practical issues. For providing a full scope in this review, we summarize the development history of Al batteries and analyze the thermodynamics and electrode kinetics of nonaqueous RABs. The progresses on the cutting-edge of the nonaqueous RABs as well as the advanced characterizations and simulation technologies for understanding the mechanism are discussed. Furthermore, major challenges of the critical battery components and the corresponding feasible strategies toward addressing these issues are proposed, aiming to guide for promoting electrochemical performance (high voltage, high capacity, large rate capability, and long cycling life) and safety of RABs. Finally, the perspectives for the possible future efforts in this field are analyzed to thrust the progresses of the state-of-the-art RABs, with expectation of bridging the gap between laboratory exploration and practical applications.

Nano Polymorphism-Enabled Redox Electrodes for Rechargeable Batteries

Nano polymorphism (NPM), as an emerging research area in the field of energy storage, and rechargeable batteries, have attracted much attention recently. In this review, the recent progress on the composition and formation of polymorphs, and the evolution processes of different redox electrodes in rechargeable metal-ion, metal-air, and metal-sulfur batteries are highlighted. First, NPM and its significance for rechargeable batteries are discussed. Subsequently, the current NPM modulation strategies of different types of representative electrodes for their corresponding rechargeable battery applications are summarized. The goal is to demonstrate how NPM could tune the intrinsic material properties, and hence, improve their electrochemical activities for each battery type. It is expected that the analysis of polymorphism and electrochemical properties of materials could help identify some "processing-structure-properties" relationships for material design and performance enhancement. Lastly, the current research challenges and potential research directions are discussed to offer guidance and perspectives for future research on NPM engineering.

Nonmetal Current Collectors: The Key Component for High-Energy-Density Aluminum Batteries

As one of the emerging safe energy-storage devices with high energy-to-cost ratio, nonaqueous aluminum batteries with enhanced energy density are intensively pursued by researchers. Although significant progress has been made on positive electrode materials, the effective energy density of aluminum batteries is still limited by the presence of high-density refractory metal current collectors, which are known to be electrochemically inert in highly acidic ionic-liquid electrolytes. To address such critical issues, here, a novel low-density (<2 g cm^-3 ) nonmetal current collector is presented, which uses poly(ethylene terephthalate) (PET) substrates coated with indium tin oxide (ITO), with the purpose of significantly reducing the ratio of nonactive components in the electrodes. In addition to the excellent chemical and electrochemical stability (with voltage as high as ≈2.75 V vs Al³⁺ /Al), this nonmetal current collector, also encompassing a carboxymethyl cellulose (CMC) binder, allows as-assembled pouch cells to deliver a reversible specific capacity of ≈120 mAh g^-1 at a current density of 50 mA g^-1 . In comparison with the high-density refractory metal Mo or Ta current collectors, these nonmetal current collectors offer a novel strategy for constructing high-energy-density aluminum batteries by substituting the key components, with the aim of boosting the energy density of nonaqueous aluminum batteries.

Three-Dimensional Molybdenum Diselenide Helical Nanorod Arrays for High-Performance Aluminum-Ion Batteries

The rechargeable aluminum-ion battery (AIB) is a promising candidate for next-generation high-performance batteries, but its cathode materials require more development to improve their capacity and cycling life. We have demonstrated the growth of MoSe₂ three-dimensional helical nanorod arrays on a polyimide substrate by the deposition of Mo helical nanorod arrays followed by a low-temperature plasma-assisted selenization process to form novel cathodes for AIBs. The binder-free 3D MoSe₂-based AIB shows a high specific capacity of 753 mAh g^-1 at a current density of 0.3 A g^-1 and can maintain a high specific capacity of 138 mAh g^-1 at a current density of 5 A g^-1 with 10 000 cycles. Ex situ Raman, XPS, and TEM characterization results of the electrodes under different states confirm the reversible alloying conversion and intercalation hybrid mechanism during the discharge and charge cycles. All possible chemical reactions were proposed by the electrochemical curves and characterization. Further exploratory works on interdigital flexible AIBs and stretchable AIBs were demonstrated, exhibiting a steady output capacity under different bending and stretching states. This method provides a controllable strategy for selenide nanostructure-based AIBs for use in future applications of energy-storage devices in flexible and wearable electronics.

Rod-shaped Cu1.81Te as a novel cathode material for aluminum-ion batteries

Aluminum-ion batteries (AIBs) are supposed to be one of the energy storage systems with great potentialities on account of their high safety, low cost and high theoretical volumetric capacity. Herein, we report a novel rod-shaped Cu1.81Te cathode material for AIBs. At 40 mA g-1, the initial discharge capacity can reach 144 mA h g-1. The diffusion coefficient of Al3+ calculated by the galvanostatic intermittent titration technique (GITT) and cyclic voltammetry (CV) tests at different scan rates is larger than that in sulfides, indicating that telluride has faster kinetics. The results of ex situ X-ray photoelectron spectroscopy (XPS), ex situ X-ray diffraction (XRD) and 27Al nuclear magnetic resonance (NMR) prove that the mechanism of the charging and discharging processes is the reversible intercalation and deintercalation of Al3+, which is very important for the subsequent researchers to understand and investigate the mechanism of the Al/Cu1.81Te battery. This work also proves that telluride can also be used as a cathode material for aluminum storage.

A strategy for massively suppressing the shuttle effect in rechargeable Al–Te batteries

Due to the chemical and electrochemical dissolution of active materials in Lewis acid electrolytes, an AB–PVDF-MS has been constructed to promote the utilization of active materials and rechargeability at both positive and negative electrodes.

Challenges and benefits of post-lithium-ion batteries

Post-Li-ion batteries based on Na, Mg, and Al offer substantial electrochemical and economic advantages in comparison with Li-ion batteries.

Nanosized MoSe2@Carbon Matrix: A Stable Host Material for the Highly Reversible Storage of Potassium and Aluminum Ions

Owing to their low cost and abundant reserves relative to conventional lithium-ion batteries (LIBs), potassium-ion batteries (PIBs), and aluminum-ion batteries (AIBs) have shown appealing potential for electrochemical energy storage, but progress so far has been limited by the lack of suitable electrode materials. In this work, we demonstrated a facile strategy to achieve highly reversible potassium and aluminum ions storage in strongly coupled nanosized MoSe₂@carbon matrix, induced through an ion complexation strategy. We present a broad range of electrochemical characterization of the synthesized product that exhibits high specific capacities, good rate capability, and excellent cycling stability toward PIBs and AIBs. Through a series of systematic ex situ X-ray photoelectron spectroscopy (XPS) characterizations and density functional theory (DFT) calculations, the Al³⁺ intercalation mechanism of MoSe₂-based AIBs are elucidated. Moreover, both the assembled PIBs and AIBs worked well when exposed to low and high temperatures within the range of -10 to 50 °C, showing promise for energy storage devices in harsh environment. The present study provides new insights into the exploration of MoSe₂ as high-performance electrode materials for PIBs and AIBs.

The Rechargeable Aluminum Battery: Opportunities and Challenges

Aluminum battery systems are considered as a system that could supplement current lithium batteries due to the low cost and high volumetric capacity of aluminum metal, and the high safety of the whole battery system. However, first the use of ionic liquid electrolytes leading to AlCl₄ ^- instead of Al³⁺ , the different intercalation reagents, the sluggish solid diffusion process and the fast capacity fading during cycling in aluminum batteries all need to be thoroughly explored. To provide a good understanding of the opportunities and challenges of the newly emerging aluminum batteries, this Review discusses the reaction mechanisms and the difficulties caused by the trivalent reaction medium in electrolytes, electrodes, and electrode-electrolyte interfaces. It is hoped that the Review will stimulate scientists and engineers to develop more reliable aluminum batteries.

H0.92K0.08TiNbO5 Nanowires Enabling High-Performance Lithium-Ion Uptake

HTiNbO₅ has been widely investigated in many fields because of its distinctive properties such as good redox activity, high photocatalytic activity, and environmental benignancy. Here, this work reports the synthesis of one-dimensional H_0.92K_0.08TiNbO₅ nanowires via simple electrospinning followed by an ion-exchange reaction. The H_0.92K_0.08TiNbO₅ nanowires consist of many small "lumps" with a uniform diameter distribution of around 150 nm. Used as an anode for lithium-ion batteries, H_0.92K_0.08TiNbO₅ nanowires exhibit high capacity, fast electrochemical kinetics, and high performance of lithium-ion uptake. A capacity of 144.1 mA h g^-1 can be carried by H_0.92K_0.08TiNbO₅ nanowires at 0.5 C in the initial charge, and even after 150 cycles, the reversible capacity can remain at 123.7 mA h g^-1 with an excellent capacity retention of 85.84%. For H_0.92K_0.08TiNbO₅ nanowires, the diffusion coefficient of lithium ions is 1.97 × 10^-11 cm² s^-1, which promotes the lithium-ion uptake effectively. The outstanding electrochemical performance is ascribed to its morphology and the formation of a stable phase during cycling. In addition, the in situ X-ray diffraction and ex situ transmission electron microscopy techniques are applied to reveal its lithium storage mechanism, which proves the structure stability and electrochemical reversibility, thus achieving high-performance lithium-ion uptake. All these advantages demonstrate that H_0.92K_0.08TiNbO₅ nanowires can be a possible alternative anode material for rechargeable batteries.