Peering into Alloy Anodes for Sodium‐Ion Batteries: Current Trends,Challenges, and Opportunities

Sodium‐ion batteries (SIBs) are regarded as a complementary technology to lithium‐ion batteries (LIBs) in the effort of searching for alternative energy solutions that are cost‐effective and sustainable. The identification of suitable alternative anode materials is essential to close the gap in energy density between SIBs and LIBs. Solid‐state alloying reactions that work beyond intercalation mechanism are able to provide a significant improvement in specific capacity. This review describes key advances in SIBs with a primary emphasis on alloy anodes. Recent information and results published in the literatures are stressed to provide an overview of their development in SIBs. With the discussion of some of the remaining challenges and possible solutions, the authors hope to sketch out the scope for future studies in this field.     

Structure Code for Advanced Polymer Electrolyte in Lithium-Ion Batteries

Over the past decade, lithium-ion batteries (LIBs) have been widely applied in consumer electronics and electric vehicles. Polymer electrolytes (PEs) play an essential role in LIBs and have attracted great interest for the development of next-generation rechargeable batteries with high energy density. Due to the several practical applications of LIBs and high demands for LIBs performance, many state-of-the-art PEs with different structures and functionalities have been developed to regulate the LIBs performance, especially their rate capability, cycling durability, and lifespan. In this review, the recent advances in high-performance LIBs prepared using well-defined PEs are summarized. The ion-transport mechanisms and preparation techniques of various well-defined PE classes compared to conventional PEs are also discussed. The aim is to elucidate the structure code for advanced PEs with optimized properties, including ionic conductivity, mechanical properties, processability, accessibility, etc. The existing challenges and future perspectives are also discussed, setting the basis for designing novel PEs for energy conversion applications.     

Lithium-Ion and Sodium-Ion Hybrid Capacitors: From Insertion-Type Materials Design to Devices Construction

There is a great appeal to develop an omnipotent player combining lithium-ion batteries (LIBs) with the capacitive storage communities. Hybrid capacitors as a kind of promising energy storage device are attracting increasing attention in the main playground in recent years. Unlike supercapacitors (SCs) and LIBs, hybrid capacitors combine a capacitive electrode with a Faradaic battery electrode. In these hybrid cells, the capacitive electrode brings the power while the energy mainly comes from the Faradaic one. Numerous efforts have been conducted in the past decades; however, the research about hybrid capacitors is still at its infancy stage, and it is not expected to replace LIBs or SCs in the near future utterly. Here, the advances of hybrid capacitors, including insertion-type materials, lithium-ion capacitors, and sodium-ion capacitors, are reviewed. This review aims to offer useful guidance for the design of faradic battery electrodes and hybrid cell construction. Brief challenges and opportunities for future research on hybrid capacitors are finally presented.     

Stable Hollow-Structured Silicon Suboxide-Based Anodes toward High-Performance Lithium-Ion Batteries

Silicon has been regarded as an attractive high-capacity anode material for next-generation lithium-ion batteries (LIBs). However, Si anodes suffer from huge volume variation during cycling, which poses a critical challenge for stable battery operation. Compared with Si, Si suboxide (SiO_x) is one of the most promising candidates for high-energy-density LIBs because of its alleviated swelling and highly stable cycling performance. Whereas, the poor electronic conductivity and low (initial) Coulombic efficiency of SiO_x anodes severely hinder practical applications for LIBs. Herein, for the first time, these issues are successfully solved through rationally designing hollow-structured SiO_x@carbon nanotubes (CNTs)/C architectures with graphitic carbon coatings and in situ growth of CNTs. When applied as anodes in LIBs, the SiO_x@CNTs/C anodes exhibit high reversible capacity, high initial Coulombic efficiency (88%), outstanding cycling performance, and extraordinary mechanical strength during the calendaring process (200 MPa). This work paves the way for developing SiO_x-based anode materials for high-energy-density LIBs.     

High Performance Composite Polymer Electrolytes for Lithium-Ion Batteries

Today, there is an urgent demand to develop all solid-state lithium-ion batteries (LIBs) with a high energy density and a high degree of safety. The core technology in solid-state batteries is a solid-state electrolyte, which determines the performance of the battery. Among all the developed solid electrolytes, composite polymer electrolytes (CPEs) have been deemed as one of the most viable candidates because of their comprehensive performance. In this review, the limitations of traditional solid polymer electrolytes and the recent progress of CPEs are introduced. The effect and mechanism of inorganic fillers to the various properties of electrolytes are discussed in detail. Meanwhile, the factors affecting ionic conductivity are intensively reviewed. The recent representative CPEs with synthetic fillers and natural clay-based fillers are highlighted because of their great potential. Finally, the remaining challenges and promising prospects are outlined to provide strategies to develop novel CPEs for high-performance LIBs.     

Feasibility of Prelithiation in LiFePO4

Lithium iron phosphate (LiFePO₄) is widely applied as the cathode material for the energy storage Li-ion batteries due to its low cost and high cycling stability. However, the low theoretical specific capacity of LiFePO₄ makes its initial capacity loss more concerning. Therefore, lithium compensation by way of prelithiation and applications of sacrificial Li-rich additives in LiFePO₄ is imminent in elevating the energy density and/or prolonging the lifetime of the LiFePO₄-based Li-ion batteries (LIBs). Prelithiation in LiFePO₄ is herein carried out by electrochemical and chemical methods and its feasibility is proved on the basis of the electrochemical evaluations such as the initial charge capacity and the cycling stability. In addition, the site of the pre-intercalated Li-ions is found via comprehensive physical characterizations and the density functional theory (DFT) calculations. These findings open a new avenue for elevating the energy density and/or prolonging the lifetime of the high-energy-density batteries.     

PCB铜蚀刻废液的治理概述

概述了PCB铜蚀刻废液的传统治理方法并对其防治效果进行了分析。此外,介绍了一种新型治理技术——铜蚀刻废液的循环再生技术。     

Layered P2‐Type K0.65Fe0.5Mn0.5O2 Microspheres as Superior Cathode for High‐Energy Potassium‐Ion Batteries

Potassium‐ion batteries have been regarded as the potential alternatives to lithium‐ion batteries (LIBs) due to the low cost, earth abundance, and low potential of K (?2.936 vs standard hydrogen electrode (SHE)). However, the lack of low‐cost cathodes with high energy density and long cycle life always limits its application. In this work, high‐energy layered P2‐type hierarchical K_0.65Fe_0.5Mn_0.5O₂ (P2‐KFMO) microspheres, assembled by the primary nanoparticles, are fabricated via a modified solvent‐thermal method. Benefiting from the unique microspheres with primary nanoparticles, the K⁺ intercalation/deintercalation kinetics of P2‐KFMO is greatly enhanced with a stabilized cathodic electrolyte interphase on the cathode. The P2‐KFMO microsphere presents a highly reversible potassium storage capacity of 151 mAh g^?1 at 20 mA g^?1, fast rate capability of 103 mAh g^?1 at 100 mA g^?1, and long cycling stability with 78% capacity retention after 350 cycles. A full cell with P2‐KFMO microspheres as cathode and hard carbon as anode is constructed, which exhibits long‐term cycling stability (>80% of retention after 100 cycles). The present high‐performance P2‐KFMO microsphere cathode synthesized using earth‐abundant elements provides a new cost‐effective alternative to LIBs for large‐scale energy storage.     

A Review of Emerging Dual-Ion Batteries: Fundamentals and Recent Advances

Dual-ion batteries (DIBs), based on the working mechanism involving the storage of cations and anions separately in the anode and cathode during the charging/discharging process, are of great interest beyond lithium-ion batteries (LIBs) in high-efficiency energy storage due to the merits of high working voltage, material availability, as well as low cost and excellent safety. Despite the progress achieved, the practical applications of DIBs are still hindered by negative issues, such as limited capacity and cyclic stability, which triggers the development of suitable electrode materials with highly reversible capacities, and corresponding electrolytes with high oxidative stability as well as sufficient reaction kinetics of active ions. Herein, in this article, a systematic and comprehensive review of fundamentals and recent advances in current DIBs with subcategories of cathode materials, anode materials, and electrolytes are presented. In particular, their energy storage mechanisms, as well as their respective features, are dissected. Furthermore, some strategies and perspectives are proposed for facilitating the further development of DIBs in the future.     

Unleashing the Potential of Sodium-Ion Batteries: Current State and Future Directions for Sustainable Energy Storage

Rechargeable sodium-ion batteries (SIBs) are emerging as a viable alternative to lithium-ion battery (LIB) technology, as their raw materials are economical, geographically abundant (unlike lithium), and less toxic. The matured LIB technology contributes significantly to digital civilization, from mobile electronic devices to zero electric-vehicle emissions. However, with the increasing reliance on renewable energy sources and the anticipated integration of high-energy-density batteries into the grid, concerns have arisen regarding the sustainability of lithium due to its limited availability and consequent price escalations. In this context, SIBs have gained attention as a potential energy storage alternative, benefiting from the abundance of sodium and sharing electrochemical characteristics similar to LIBs. Furthermore, high-entropy chemistry has emerged as a new paradigm, promising to enhance energy density and accelerate advancements in battery technology to meet the growing energy demands. This review uncovers the fundamentals, current progress, and the views on the future of SIB technologies, with a discussion focused on the design of novel materials. The crucial factors, such as morphology, crystal defects, and doping, that can tune electrochemistry, which should inspire young researchers in battery technology to identify and work on challenging research problems, are also reviewed.     

Achieving High Volumetric Lithium Storage Capacity in Compact Carbon Materials with Controllable Nitrogen Doping

Although nanostructured/nanoporous carbon and silicon‐based materials are a potential replacement for graphite as cost‐effective anodes for lithium ion batteries (LIBs), their extremely low packing density leads to considerably reduced volumetric capacities. Herein, a highly compact carbon anode material constructed from sub‐2 nm nanosized graphitic domains is reported that exhibits excellent capacity density. By introducing a coordination agent in the synthesis precursors, an unusually high concentration of N‐doping (≈26.56 wt%) is achieved, which is mainly confined at the graphitic edges with the pyrrolic‐N and pyridinic‐N configurations. As further supported experimentally and theoretically, the edge‐N dopants, particularly the pyrrolic‐N, favor both ion diffusion kinetics and lithium storage via adsorption. Based on the lithiation‐state electrode volume, the compact anode shows a capacity density of 951 mAh cm_total^?3 that is comparable with Si anodes and surpasses all reported carbon‐based anodes, revealing its potential in promoting the performance of future LIBs.     

A Self‐Standing and Flexible Electrode of Li4Ti5O12 Nanosheets with a N‐Doped Carbon Coating for High Rate Lithium Ion Batteries

Flexible energy‐storage devices have attracted growing attention with the fast development of bendable electronic systems. Thus, the search for reliable electrodes with both high mechanical flexibility and excellent electron and lithium‐ion conductivity has become an urgent task. Carbon‐coated nanostructures of Li₄Ti₅O₁₂ (LTO) have important applications in high‐performance lithium ion batteries (LIBs). However, these materials still need to be mixed with a binder and carbon black and pressed onto metal substrates or, alternatively, by be deposited onto a conductive substrate before they are assembled into batteries, which makes the batteries less flexible and have a low energy density. Herein, a simple and scalable process to fabricate LTO nanosheets with a N‐doped carbon coating is reported. This can be assembled into a film which can be used as a binder‐free and flexible electrode for LIBs that does not require any current collectors. Such a flexible electrode has a long life. More significantly, it exhibits an excellent rate capability due to the thin carbon coating and porous nanosheet structures, which produces a highly conductive pathway for electrons and fast transport channels for lithium ions.     

Nanostructured Metal Chalcogenides for Energy Storage and Electrocatalysis

Energy storage and conversion technologies are vital to the efficient utilization of sustainable renewable energy sources. Rechargeable lithium‐ion batteries (LIBs) and the emerging sodium‐ion batteries (SIBs) are considered as two of the most promising energy storage devices, and electrocatalysis processes play critical roles in energy conversion techniques that achieve mutual transformation between renewable electricity and chemical energies. It has been demonstrated that nanostructured metal chalcogenides including metal sulfides and metal selenides show great potential for efficient energy storage and conversion due to their unique physicochemical properties. In this feature article, the recent research progress on nanostructured metal sulfides and metal selenides for application in SIBs/LIBs and hydrogen/oxygen electrocatalysis (hydrogen evolution reaction, oxygen evolution reaction, and oxygen reduction reaction) is summarized and discussed. The corresponding electrochemical mechanisms, critical issues, and effective strategies towards performance improvement are presented. Finally, the remaining challenges and perspectives for the future development of metal chalcogenides in the energy research field are proposed.     

A Zn–CO2 Flow Battery Generating Electricity and Methane

Metal–CO₂ batteries represent an economical and efficient CO₂ utilization technique, which provides a mechanism combining CO₂ reduction with electricity generation instead of electricity input. Existing metal–CO₂ batteries generally work in a closed system by recycling CO₂. In this study, a flow battery is designed with a hollow fiber of carbon nanotubes (cathode), Zn wire (anode), and 1‐ethyl‐3‐methylimidazolium tetrafluoroborate (electrolyte). The battery can continuously consume CO₂ to produce CH₄ under ambient conditions and promptly output the gaseous product through the hollow fiber, with a Faradaic efficiency up to 94%. Simultaneously, the battery generates electricity, with an energy density of 288.3 Wh kg^?1 (based on the zinc mass) and a stability up to 8 days. The high selectivity and efficiency of the battery is attributed to a water‐shuttling assisted proton mechanism and delicate electrode–electrolyte interplay. Moreover, the Zn anode is electrochemically renewed and the battery assembled with the regenerated Zn anode restores battery performances to the former level. The renewable characteristic implies that, if the regeneration of Zn anode is coupled to excessive renewable energy sources, then the Zn–CO₂ flow battery will be promising to accomplish a net reduction of CO₂ emission.     

Tin Oxide with Controlled Morphology and Crystallinity by Atomic Layer Deposition onto Graphene Nanosheets for Enhanced Lithium Storage

As one of the most promising negative electrode materials in lithium‐ion batteries (LIBs), SnO₂ experiences intense investigation due to its high specific capacity and energy density, relative to conventional graphite anodes. In this study, for the first time, atomic layer deposition (ALD) is used to deposit SnO₂, containing both amorphous and crystalline phases, onto graphene nanosheets (GNS) as anodes for LIBs. The resultant SnO₂‐graphene nanocomposites exhibit a sandwich structure, and, when cycled against a lithium counter electrode, demonstrate a promising electrochemical performance. It is demonstrated that the introduction of GNS into the nanocomposites is beneficial for the anodes by increasing their electrical conductivity and releasing strain energy: thus, the nanocomposite electrode materials maintain a high electrical conductivity and flexibility. It is found that the amorphous SnO₂‐GNS is more effective than the crystalline SnO₂‐GNS in overcoming electrochemical and mechanical degradation; this observation is consistent with the intrinsically isotropic nature of the amorphous SnO₂, which can mitigate the large volume changes associated with charge/discharge processes. It is observed that after 150 charge/discharge cycles, 793 mA h g^?1 is achieved. Moreover, a higher coulombic efficiency is obtained for the amorphous SnO₂‐GNS composite anode. This study provides an approach to fabricate novel anode materials and clarifies the influence of SnO₂ phases on the electrochemical performance of LIBs.     

Fundamental Understanding and Facing Challenges in Structural Design of Porous Si-Based Anodes for Lithium-Ion Batteries

As one of the most electrochemical energy storage devices, lithium-ion batteries (LIBs) remain the workhorse of the energy market due to their unparalleled advantages. Remarkably, Si-based materials play a pivotal role in LIBs anodes owing to ultrahigh theoretical capacity of Si and rich natural resources. However, bulk silicon materials are difficult to meet the current commercial demand because of their low conductivity, sluggish reaction kinetics, and huge volume expansion. The construction of porous structures has been acknowledged as an effective way to solve the above issues. Herein, the delicate design of porous Si-based anode materials including synthetic strategies, the engineering of surface morphology and micro/nano-structure, and the regulation of different compositions, as well as their applications in LIBs is systematically summarized. Particularly, the fine engineering of different pore parameters for Si-based materials is on focus. Importantly, the relationship between thick electrodes and tortuosity/porosity, and the structural effect between pores and battery performance are also discussed in depth. Finally, the applications of porous Si-based anodes in full-cells and their commercial achievements are briefly described. This review is expected to provide a basic understanding and deep insight into developing porous Si-based anodes for high-energy lithium storage.     

Magnetic Multi‐Functional Nano Composites for Environmental Applications

A novel concept is proposed to synthesize a new class of composites featuring magnetic, molecular sieve and metallic nanoparticle properties. These multi‐functional materials have potential applications as recyclable catalysts, disinfectants and sorbents. The magnetic property enables effective separation of the spent composites from complex multiphase systems for regeneration and recycle, safe disposal of the waste and/or recovery of loaded valuable species. The zeolite molecular sieve provides a matrix which supports a remarkably new, simple, efficient and economical method to make stable, supported silver nanoparticles by silver ion exchange and controlled thermal reduction. The silver nanoparticles generated in this way have excellent properties such as high reactivity and good thermal stability without aggregation, which act as nano reactors for desired functionality in a wide range of applications. Magnetic component (Fe₃O₄), molecular sieve matrix (zeolite) and silver nanoparticles generated by ion exchange followed by controlled reduction, together form this unique novel composite with designed functions. It represents a practically operational, economical, sustainable and environmentally friendly new advanced functional material. This paper focuses on the novel synthesis and characterization of the composite, with an example of applications as sorbents for the removal of vapor‐phase mercury from the flue gas of coal‐fired power plants.     

Porosity‐ and Graphitization‐Controlled Fabrication of Nanoporous Silicon@Carbon for Lithium Storage and Its Conjugation with MXene for Lithium‐Metal Anode

Silicon (Si) and lithium metal are the most favorable anodes for high‐energy‐density lithium‐based batteries. However, large volume expansion and low electrical conductivity restrict commercialization of Si anodes, while dendrite formation prohibits the applications of lithium‐metal anodes. Here, uniform nanoporous Si@carbon (NPSi@C) from commercial alloy and CO₂ is fabricated and tested as a stable anode for lithium‐ion batteries (LIBs). The porosity of Si as well as graphitization degree and thickness of the carbon layer can be controlled by adjusting reaction conditions. The rationally designed porosity and carbon layer of NPSi@C can improve electronic conductivity and buffer volume change of Si without destroying the carbon layer or disrupting the solid electrolyte interface layer. The optimized NPSi@C anode shows a stable cyclability with 0.00685% capacity decay per cycle at 5 A g^?1 over 2000 cycles for LIBs. The energy storage mechanism is explored by quantitative kinetics analysis and proven to be a capacitance‐battery dual model. Moreover, a novel 2D/3D structure is designed by combining MXene and NPSi@C. As lithiophilic nucleation seeds, NPSi@C can induce uniform Li deposition with buffered volume expansion, which is proven by exploring Li‐metal deposition morphology on Cu foil and MXene@NPSi@C. The practical potential application of NPSi@C and MXene@NPSi@C is evaluated by full cell tests with a Li(Ni_0.8Co_0.1Mn_0.1)O₂ cathode.     

Review on the Binders for Sustainable High-Energy-Density Lithium Ion Batteries: Status,Solutions, and Prospects

The upsurging demand for electric vehicles and the rapid consumption of lithium-ion batteries (LIBs) calls for LIBs to possess high energy density and resource sustainability. The former requires the usage of electroactive materials with high capacity and the maximum amount within the fixed electrode volume. The latter essentially creates a closed-loop circulation scenario for electroactive materials. In all aspects, binders are of practical significance in bonding electroactive materials, maintaining electrode integrity and detaching electrode slurry from the current collector. Currently, the key role of binders in enhancing the electrochemical behavior of sustainable high-capacity electroactive materials has been recognized. Meanwhile, binders that are designed for easy and cost-effective recycling of electroactive materials are gradually reported. Herein, recently developed binders that hold promises in establishing sustainable high-energy-density LIBs are summarized. The role of binder in facilitating easy separation of electroactive materials are first highlighted. Subsequently, special attention is paid to conductive binders, contributing to less battery chemistries and higher energy density of electrode. Additionally, progress of emerging binders in high-capacity electroactive materials are also reviewed. It is believed that the advances in binders will open up opportunities for establishing a sustainable high-energy-density battery economy.     

Polymer Molecular Engineering Enables Rapid Electron/Ion Transport in Ultra-Thick Electrode for High-Energy-Density Flexible Lithium-Ion Battery

Flexible lithium-ion batteries (LIBs) with high energy density are of urgent need for the ever-increasing flexible and wearable electronic equipments, but limited by the low areal loading of active materials in traditional electrodes with lamellar structure. It is still a great challenge to solve the sluggish electron/ion transport problem caused by increasing the areal loading of active materials. Herein, a kind of ethylene vinyl acetate copolymer (EVA) is proposed to provide flexible supports and ion channels for ultra-thick flexible LFP/CNT/EVA cathode and LTO/CNT/EVA anode, thereby achieving high energy density and all flexible LIBs. LFP/CNT/EVA shows a ternary homogeneous structure formed by the entanglement of EVA chains and CNT on LFP, which attributes to LFP content up to 80wt% and adjustable thickness from 20 to 460 µm. In sharp contrast to previous studies LFP/CNT/EVA delivers basically the constant specific capacity of ≈160 mAh g⁻¹ at a 0.1 C rate with the thickness increasing, thus achieving ultrahigh areal capacity up to 4.56 mAh cm⁻². A flexible full LIBs based on LFP/CNT/EVA and LTO/CNT/EVA is demonstrated and exhibits favorable cycle performance under an alternant flat and bending state. Those findings are supposed to open new avenues for designing high-energy-density flexible LIBs for future wearable energy storage devices.