Silicon (Si) has emerged as a promising anode material in the pursuit of higher energy-density lithium-ion batteries (LIBs). The large-scale applications of Si anode, however, are hindered by its significant swelling, severe pulverization, and continuous electrode-electrolyte reaction. Therefore, the development of an efficient approach to mitigate Si particle swelling and minimize interface parasitic reactions has emerged as a prominent research focus in both academia and industry. Here, a facile and scalable strategy is reported for the preparation of a double-layer coated submicron Si anode, comprising ceramic (silicon oxide) and graphene layers, denoted as Si@SiO_x@G. In this approach, SiOx is in situ synthesized on the surface of Si and bonded with graphene through hydrogen bond interactions. The prepared Si electrode shows exceptional structural integration and demonstrates outstanding electrochemical stability, with a capacity retention of 92.58% after 540 cycles at 1 A g⁻¹, as well as remarkable rate capability, achieving a specific capacity of 875 mAh g⁻¹ at 2 A g⁻¹. This study presents a straightforward yet pragmatic approach for the widespread implementation of high-energy-density siliconbased batteries.

Graphite is one of the most widely used anode materials in lithium-ion batteries (LIBs). The recycling of spent graphite (SG) from spent LIBs has attracted less attention due to its limited value, complicated contaminations, and unrestored structure. In this study, a remediation and regeneration process with combined hydrothermal calcination was proposed to remove different impurities as value-added resources from SG. This study focuses on the application of different removal methods for different impurity metals by hydrothermal and acid leaching under different conditions for the removal of Cu, Li, Co, Mn, and Ni from SG. Then, mild-tempreture calcination of SG was performed to remove residual organic compounds. The regenerated graphite (RG) was found to have a better morphology structure and increased pore volume, which is more favorable for the embedding and desorption of lithium (Li) in graphite. In terms of electrochemical performance, the first dischargespecific capacity of RG at 0.5 C is 359.40 mAh/g, with a retention of 353.49 mAh/g after 100 cycles (retention rate of 98.36%). This study can be a green and efficient candidate for the regeneration of graphite from spent lithium-ion batteries as anode material by reduced restoration temperature, with different metal resources as by-products.

High energy density Ni-rich layered oxide cathodes LiNi_0.83Co_0.12Mn_0.05–xAl_xO₂ (x = 0 [NMC], 0.025 [NMCA], 0.05 [NCA]) are fabricated in two different microstructural forms: (i) nanoparticles (NP) and (ii) nanofibers (NF), to evaluate the morphology and compositional effect on the electrochemical properties using same precursors, with the latter fabricated by electrospinning process. Although all the cathodes exhibit a similar crystal structure as confirmed using X-ray diffraction and Raman spectroscopy, the contrasting difference is observed in their electrochemical properties. XRD and XPS analyses indicate a higher amount of cationic disorder for the NP cathodes compared to their NF counterparts. Nanofibrous Ni-rich layered oxide cathodes exhibit higher discharge capacities at all C-rates in comparison to NP cathodes. When cycled at 1C-rate for 100 cycles, capacity retention of 81% is observed for NCA-NF, which is superior to all cathodes. Voltage decay as a function of the charge-discharge cycle is found to be low (0.2mV/cycle) for nanofibrous cathodes compared to 1.5mV/cycle for NP cathodes. The good rate capability and cyclic stability of nanofibrous Ni-rich layered oxide cathodes are attributed to a shorter pathway of Li⁺ diffusion and a large proportion of the active surface area.

Lithium-ion batteries suffer from severe capacity loss and even fail to work under subzero temperatures, which is mainly due to the sluggish Li+ transportation in the solid electrolyte interphase (SEI) and desolvation process. Ethyl acetate (EA) is a highly promising solvent for lowtemperature electrolytes, yet it has poor compatibility with graphite (Gr) anode. Here, we tuned the interfacial chemistry of EA-based electrolytes via synergies of anions. ODFB− with low solvation numbers, participates in the solvation sheath, significantly reducing the desolvation energy. Meanwhile, combined with the high dissociation of FSI⁻, the reduction of both anions constructs an inorganic-rich SEI to improve interfacial stability. The electrolyte enables Gr anode to deliver a capacity of 293 mA h g⁻¹ and 2.5 Ah LiFePO₄∥Gr pouch cell to exhibit 96.85% capacity retention at −20°C. Remarkably, LiFePO₄∥Gr pouch cell with the designed electrolyte can still retain 66.28% of its room-temperature capacity even at −40°C.

Aqueous zinc-based batteries (AZBs) with the advantages of high safety, low cost, and satisfactory energy density are regarded as one of the most promising candidates for future energy storage systems. Rampant dendrite growth and severe side reactions that occur at the Zn anode hinder its further development. Recently, a growing number of studies have demonstrated that side reactions are closely related to the active water molecules belonging to the Zn²⁺ solvated structure in the electrolyte, and reducing the occurrence of side reactions by regulating the relationship between the above two has proven to be a reliable pathway. Nevertheless, a systematic summary of the intrinsic mechanisms and practical applications of the route is lacking. This review presents a detailed description of the close connection between H₂O and side reactions at Zn anodes and gives a comprehensive review of experimental strategies to inhibit side reactions by modulating the relationship between Zn²⁺ and H₂O, including anode interface engineering and electrolyte engineering. In addition, further implementation of the above strategies and the modification means for future Zn anodes are discussed.

All-solid-state lithium (Li) metal batteries combine high power density with robust security, making them one of the strong competitors for the next generation of battery technology. By replacing the flammable and volatile electrolytes commonly found in traditional Li-ion batteries (LIBs) with noncombustible solid-state electrolytes (SSEs), we have the potential to fundamentally enhance safety measures. Concurrently, SSE would be capable of fitting high specific capacity (3860 mAh g^-1) metal Li and is expected to break through the upper limit of mass-energy density (350 Wh kg^-1) of existing LIBs system. Nevertheless, the growth of Li dendrites on the negative side or the nucleation of Li inside SSEs may give rise to battery short circuits, which is the primary factor limiting the application of Li metal. Recognizing this, the focus of this review is to provide a perspective for experimentalists and theorists who closely monitor various surface/interface and microstructure phenomena to understand Li dendrites. The strategies to reveal the complicated deposition mechanism and to control the dendrite growth of metal Li in solid-state batteries, as well as the advanced characterization methods of metal Li, provide suggestions for the practical research of solid-state Li metal batteries.

Wearable electronics are expected to be light, durable, flexible, and comfortable. Many fibrous, planar, and tridimensional structures have been designed to realize flexible devices that can sustain geometrical deformations, such as bending, twisting, folding, and stretching normally under the premise of relatively good electrochemical performance and mechanical stability. As a flexible electrode for batteries or other devices, it possesses favorable mechanical strength and large specific capacity and preserves efficient ionic and electronic conductivity with a certain shape, structure, and function. To fulfill flexible energy-storage devices, much effort has been devoted to the design of structures and materials with mechanical characteristics. This review attempts to critically review the state of the art with respect to materials of electrodes and electrolyte, the device structure, and the corresponding fabrication techniques as well as applications of the flexible energy storage devices. Finally, the limitations of materials and preparation methods, the functions, and the working conditions of devices in the future were discussed and presented.

Cu(OH)₂ has the advantages of ease of structural regulation, good conductivity, and relatively low cost, making it a suitable candidate material for use as an electrocatalyst. However, its catalytic efficiency and stability still need to be improved further. Therefore, Cu(OH)₂/Cu₂S was successfully prepared on copper foam (CF) using the in situ growth and hydrothermal method. The structural characterization showed that sulfidation treatment induced transformation of Cu(OH)₂/CF from smooth nanorods into a corallike structure, which exposed more active sites of Cu(OH)₂/Cu₂S and enhanced the performance of electrocatalytic hydrogen evolution reaction (HER). Compared with Cu(OH)₂, Cu(OH)₂/Cu₂S showed better alkaline HER performance, especially when the vulcanization concentration was 0.1 M, the overpotential of Cu(OH)₂/Cu₂S was 174 mV, and the reaction kinetics was 64 mv dec⁻¹ at a current density of 10mA cm⁻². In this work, the morphology and electronic structure of copper-based metal sulfide electrocatalysts were adjusted by sulfide treatment, which provided a new reference for improving HER performance.

Ideally, once batteries reach their end-of-life, they are expected to be collected, dismantled, and converted into black mass (BM), which contains significant amounts of valuable metals. BM can be regarded as a sort of urban mine, where recyclers extract and reintroduce the materials into new battery manufacturing. Focusing on BM, this article discusses the necessity of BM recovery and current recycling situations. Although the benefits of recycling are widely acknowledged, many challenges and issues remain. The BM market is still in its infancy and relevant regulatory frameworks need to be updated with respect to the widespread use and advancement of lithium-ion batteries. Current BM producing and processing technologies are gaining momentum and still have room for large improvements in terms of economic feasibility and environmental footprint. Finding solutions for these challenges in the end requires efforts from both researchers and industrial stakeholders with growing interests and long-term patient engagement. Battery regulations and legal support are highly anticipated for industries to keep high levels of commitment to long-term investments.

Layered oxides are successful cathode materials for sodium-ion batteries. Many of these oxides show interesting kinetic behavior but have poor structural stability. To overcome this limitation, an alternative material containing potassium in the interlayer space in trigonal prismatic coordination is studied here. The transition-metal layers are formed by sustainable transition elements such as iron and manganese. The solid was prepared using a sol-gel procedure that led to a product with relatively high purity, with a P’3-type structure indexable in the C2/m space group of the monoclinic system. Its electrochemical behavior was studied in sodium metal half-cells. When the cell is charged up to 4.3 V, it is observed that the potassium extraction is not complete. The subsequent discharge of the cell is associated with the intercalation of sodium from the electrolyte. Thus, it is possible to incorporate a greater number of alkaline ions than those extracted in the previous charge. The residual potassium in the structure was found to be favorable to maintaining the structural integrity of the compound upon cycling. This can be explained by the beneficial effect of potassium, which would act as a structural “pillar” in the interlayer, which would reduce structural degradation during cycling.

Despite their great promise as high-energy-density alternatives to Li-ion batteries, the extensive use of lithium-oxygen (Li-O₂) batteries is constrained by the slow kinetics of both the oxygen evolution reaction and oxygen reduction reaction. To increase the overall performance of Li-O₂ batteries, it is essential to increase the efficiency of oxygen electrode reactions by constructing effective electrocatalysts. As a high-efficiency catalyst for Li-O₂ batteries, high entropy perovskite oxide (La_0.8Sr_0.2)(Mn_0.2Fe_0.2Cr_0.2Co_0.2Ni_0.2)O₃ (referred to as LS (MFCCN)O₃) is designed and investigated in this article. The introduction of dissimilar metals in LS(MFCCN)O₃ has the potential to cause lattice deformation, thereby enhancing electron transfer between transition metal ions and facilitating the formation of numerous oxygen vacancies. This feature is advantageous for the reversible production and breakdown of discharge product Li₂O₂. Consequently, the Li-O₂ battery utilizing LS(MFCCN)O₃ as a catalyst achieves an impressive discharge capacity of 17,078.2mAh g⁻¹ and exhibits an extended cycling life of 435 cycles. This study offers a useful method for adjusting the catalytic performance of perovskite oxides toward oxygen redox reactions in Li-O₂ batteries.

Bismuth trioxide (BT) is considered a fascinating anode material for hybrid supercapacitors (HSCs) due to its high theoretical capacity, but the low conductivity limits further applications. With this in mind, Ce-doped Bi₂O₃ (Ce-BT) nanoflower spheres were synthesized by a facile and rapid microwave-assisted solvothermal method for HSCs anode materials. It is found that the morphology of BT could be controlled by Ce doping from stacked nanosheets to well-dispersed nanoflowers spheres and producing abundant amorphous regions, thus expediting the ion transport rate. Consequently, when the added Bi to Ce molar ratio is 40:1 (Ce-BT-40), it exhibited a specific capacity of 220 mAh g^-1 at 0.5 A g^-1. Additionally, when fabricating HSCs with as-prepared Ce-BT-40 and CeNiCo-LDH, an energy density of 59.1 Wh kg^-1 is provided at a power density of 652Wkg^-1. This work not only reveals the mechanism of the effect of Ce doping on the electrochemical properties of BTs, but also proposes a rapid synthesis method of Ce-BTs by microwave-assisted solvent method, which provides new insights for building advanced HSCs with high energy density and low cost.

As demand for extended range in electric vehicles and longer battery lifetimes in consumer electronics has grown, so have the requirements for higher energy densities and longer cycle lifetimes of the cells that power them. One solution to this is the implementation of an “anode-free” battery. By removing the anode and plating lithium directly onto the current collector, it is possible to access the same capacities and voltage windows as traditional lithium metal batteries, with the entirety of the lithium source coming from the cathode. Herein, a copper foil current collector coated with niobium oxide or lithium niobium oxide through atomic layer deposition (ALD) is applied to extend the cycling life of the anode-free batteries by reducing dendrite formation and improving the stability of the lithium metal surface throughout cycling. The ALD coatings are able to extend the cycle lifetime in full coin cells from 20 cycles to 80% capacity retained in the bare copper controls to 50 and 115 cycles for the NbO and LiNbO coatings, respectively. Over the lifetime of the cells, the ALD-LiNbO is able to cumulatively offer a staggering improvement of an additional 100 kWh L⁻¹ compared to the bare copper control.

Rechargeable lithium-metal batteries (LMBs) hold great promise for providing high-energy density. However, their widespread commercial adoption has been inhibited by critical challenges, for example, the capacity fading from irreversible processes at electrolyte/electrode interfaces and safety concerns originating from the inhomogeneous lithium deposition. Polymer electrolytes benefiting from enhanced electrolyte/electrode contact and low interfacial impedance provide a variable solution to address these challenges and enable a high-energy and flexible battery system. Although promising, inefficient bulky ionic conductivity and poor mechanical stability confront the stable operation of polymer electrolytes in tangible batteries, which highly requires the development of innovative polymer electrolyte chemistries. Among various polymer materials, microporous polymers stand out due to their abundant porosity and customizable micropore structure, positioning them as promising candidates for next-generation electrolyte membranes. This review, therefore, summarizes recent advances in electrolyte membranes based on two new chemistries, hypercrosslinked polymers (HCPs) and porous coordination polymers (PCPs). Other microporous polymers, such as covalent organic polymers, porous organic cages, and polymers of intrinsic microporosity, are also discussed with an emphasis on their applications in LMBs. Most importantly, by reviewing the design strategies, synthesis protocols, and performance in LMBs, we gain insights into the design principles of highperformance electrolyte membranes based on HCPs and PCPs and highlight potential future research directions.

The aqueous metal–H₂O₂ batteries have been paid rapidly increasing attention due to their large theoretical energy densities, attractive power density, and multiple applications (air, land, and sea), especially in low-content oxygen or nonoxygen conditions in which metal–air cells are out of work. However, the requirements of metal–H₂O₂ batteries are different due to the order of metal activities (Mg > Al > Zn) as well as metal–air cells. Aqueous metal–H₂O₂ batteries mainly include Al–H₂O₂, Mg–H₂O₂, and Zn–H₂O₂ batteries with the respective scientific problems, including battery structures, single/dualelectrolyte systems, electrocatalysts for O2 reduction/evolution reactions, H₂O₂ reduction/production/decomposition, and the designability of anode to inhibit self-corrosion. In this review, we summarized battery architectures, possible mechanisms, and recent progress in metal–H₂O₂ batteries, including Al–H₂O₂, Mg–H₂O₂, and Zn–H₂O₂ batteries. Several perspectives are also provided for these research fields, which may be focused on in the future.