Silicon-Based Lithium Ion Battery Systems: State-of-the-Art from Half and Full Cell Viewpoint

Lithium-ion batteries (LIBs) have been occupying the dominant position in energy storage devices. Over the past 30 years, silicon (Si)-based materials are the most promising alternatives for graphite as LIB anodes due to their high theoretical capacities and low operating voltages. Nevertheless, their extensive volume changes in battery operation causes the structural collapse of Si-based electrodes, as well as severe side reactions. In this review, the preparation methods and structure optimizations of Si-based materials are highlighted, as well as their applications in half and full cells. Meanwhile, the developments of promising electrolytes, binders and separators that match Si-based electrodes in half and full cells have made great progress. Pre-lithiation technology has been introduced to compensate for irreversible Li⁺ consumption during battery operation, thereby improving the energy densities and lifetime of Si-based full cells. More importantly, almost all related mechanisms of Si-based electrodes in half and full cells are summarized in detail. It is expected to provide a comprehensive insight on how to develop high-performance Si-based full cells. The work can help us understand what happens during the lithiation process, the primary causes of Si-based half and full cells failure, and strategies to overcome these challenges.     

硅基发光材料研究进展

阐述了等电子杂质、掺Er硅、硅基量子结构(包括量子阱、量子线和量子点)及多孔硅的发光机理,综述了90年代以来a-Si/SiO2、SiGe/Si等Si基异质结构材料的优异特性和诱人的应用前景,着重介绍了能带工程为Si基异质结构带来的新特性、新功能,重点介绍了硅基量子点的制备和发光机理,综述了半导体量子点材料的最新发展动态和发展趋势。     

Nanostructured Silicon Anodes for High‐Performance Lithium‐Ion Batteries

Despite the high theoretical capacity of Si anodes, the electrochemical performance of Si anodes is hampered by severe volume changes during lithiation and delithiation, leading to poor cyclability and eventual electrode failure. Nanostructured silicon and its nanocomposite electrodes could overcome this problem holding back the deployment of Si anodes in lithium‐ion batteries (LIBs) by providing facile strain relaxation, short lithium diffusion distances, enhanced mass transport, and effective electrical contact. Here, the recent progress in nanostructured Si‐based anode materials such as nanoparticles, nanotubes, nanowires, porous Si, and their respective composite materials and fabrication processes in the application of LIBs have been reviewed. The ability of nanostructured Si materials in addressing the above mentioned challenges have been highlighted. Future research directions in the field of nanostructured Si anode materials for LIBs are summarized.     

Bi Dots Confined by Functional Carbon as High-Performance Anode for Lithium Ion Batteries

Fabrication of Bi/C composites is a common approach to alleviate the severe volume expansion of Bi alloy-based anodes with a high theoretical capacity of 3800 mAh cm⁻³ for lithium ion batteries (LIBs). However, the complicated and tedious synthetic routes restrict its large-scale preparation and practical applications. Herein, a spongiform porous Bi/C composite (marked as Bi@PC) through the carbothermal reduction (CTR) method is constructed. Bi nanodots are in situ confined in a porous carbon substrate activated by the gases produced from the decomposition of the sodium phytate precursor, indicating the feasibility and simplicity of this route. In charge/discharge processes, Bi nanodots embedded in carbon matrix are effective enough to accommodate the strain change and shorten the migration distance. In addition, the porous carbon forms an efficient conductive network for electron shutting. When utilized for lithium storage, a superb capacity of 520 mAh g⁻¹ at 0.2 A g⁻¹ after 100 cycles and a satisfying long cyclic stability of 380 mAh g⁻¹ at 0.5 A g⁻¹ after 500 cycles are achieved. The excellent Li-storage performance and this handy preparation method jointly make this Bi/C composite a potential anode for LIBs, and could inspire the preparation of other alloy-type anodes.     

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.     

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.     

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.     

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.     

Hierarchically Structured Porous Materials for Energy Conversion and Storage

Materials with hierarchical porosity and structures have been heavily involved in newly developed energy storage and conversion systems. Because of meticulous design and ingenious hierarchical structuration of porosities through the mimicking of natural systems, hierarchically structured porous materials can provide large surface areas for reaction, interfacial transport, or dispersion of active sites at different length scales of pores and shorten diffusion paths or reduce diffusion effect. By the incorporation of macroporosity in materials, light harvesting can be enhanced, showing the importance of macrochannels in light related systems such as photocatalysis and photovoltaics. A state‐of‐the‐art review of the applications of hierarchically structured porous materials in energy conversion and storage is presented. Their involvement in energy conversion such as in photosynthesis, photocatalytic H₂ production, photocatalysis, or in dye sensitized solar cells (DSSCs) and fuel cells (FCs) is discussed. Energy storage technologies such as Li‐ions batteries, supercapacitors, hydrogen storage, and solar thermal storage developed based on hierarchically porous materials are then discussed. The links between the hierarchically porous structures and their performances in energy conversion and storage presented can promote the design of the novel structures with advanced properties.     

A Low Strain A-Site Deficient Perovskite Lithium Lanthanum Niobate Anode for Superior Li+ Storage

The oxide perovskite family holds great promise for diverse applications on account of their unique chemical and physical properties. However, owing to the inadequate Li⁺-storage sites, the insertion-type perovskite anodes for lithium-ion batteries (LIBs) are limited. A-site deficient perovskites with rich intrinsic vacancies and ion transport channels are believed to be the desirable hosts of superior Li⁺ storage. Herein, the perovskite Li_0.1La_0.3NbO₃ (LLNO) is designed and demonstrated as the remarkable anode for LIBs with a high specific capacity, a safe operating voltage, an excellent rate performance, and a long cycling life. More importantly, the outstanding cycling stability of LLNO is originated from its low strain characteristic with a maximum volume change of only 1.17%. The exceptional rate performance can be explained by the unconventional Li⁺ transport pathways with external → grain boundaries → lattice deficiencies. These results not only reveal that A-site deficient perovskite LLNO is a promising anode for LIBs but also provide fundamental insights into the Li⁺ ions transport mechanism, facilitating the development of high-performance perovskite anodes.     

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.     

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.     

Composite Separators for Robust High Rate Lithium Ion Batteries

Lithium ion batteries (LIBs) are one of the most potential energy storage devices among various rechargeable batteries due to their high energy/power density, long cycle life, and low self-discharge properties. However, current LIBs fail to meet the ever-increasing safety and fast charge/discharge demands. As one of the main components in LIBs, separator is of paramount importance for safety and rate performance of LIBs. Among the various separators, composite separators have been widely investigated for improving their thermal stability, mechanical strength, electrolyte uptake, and ionic conductivity. Herein, the challenges and limitations of commercial separators for LIBs are reviewed, and a systematic overview of the state-of-the-art research progress in composite separators is provided for safe and high rate LIBs. Various combination types of composite separators including blending, layer, core–shell, and grafting types are covered. In addition, models and simulations based on the various types of composite separators are discussed to comprehend the composite mechanism for robust performances. At the end, future directions and perspectives for further advances in composite separators are presented to boost safety and rate capacity of LIBs.     

Pristine Metal–Organic Frameworks and their Composites for Renewable Hydrogen Energy Applications

Metal–organic frameworks (MOFs) have emerged as ideal multifunctional platforms for renewable hydrogen (H₂) energy applications owing to their tunable chemical compositions and structures and high porosity. Their advanced component species and porous structure contribute greatly to the enhanced activity, electrical conductivity, photo response, charge-hole separation efficiency, and structural stability of MOF materials, which are promising for practical H₂ economy. In this review, we mainly introduce design strategies for the enhancement of electro-/photochemical behaviors or adsorption performance of porous MOF materials for H₂ production, storage, and utilization from compositional perspective. Following these engineering strategies, the correlation between composition and property-structure-performance of pristine MOFs and their composite with advanced components is illustrated. Finally, challenges and directions of future development of related MOFs and MOF composites for H₂ economy are provided.     

Insights on Artificial Interphases of Zn and Electrolyte: Protection Mechanisms,Constructing Techniques,Applicability, and Prospective

Aqueous zinc-ion batteries (ZIBs) with metallic Zn anodes have emerged as promising candidates for large-scale energy storage systems due to their inherent safety and competitive capacity. However, challenges of Zn anodes, including dendrite growth and side reactions, impede the commercialization of ZIBs. The regulation of the Zn/electrolyte interphase is a feasible method to achieve high-performance ZIBs with prolonged lifespan and high reversibility. Considering the as-made artificial interphase is the result of a combination of protection materials, protection mechanisms, and construction techniques, this review comprehensively summarizes the recent progress of interphase modulation and provides a systematic guideline for constructing ideal artificial layers. In addition to revealing the entanglement relationship between the failure behaviors of Zn anodes and timely concluding the emerging protection mechanisms for stable Zn/electrolyte interphase, this review also evaluates the constructing techniques in regard of commercialization, including engineering workflow, strength, shortcoming, applicable materials, and protection effect, aiming to pave the way to practical application. Finally, this review presents noteworthy points of ideal artificial layer. It is expected that this review can enlighten researchers to not only explore ideal interphases of Zn anodes for practical application, but also design other metal anodes in aqueous batteries with similar failure behaviors.     

A General Strategy for Antimony-Based Alloy Nanocomposite Embedded in Swiss-Cheese-Like Nitrogen-Doped Porous Carbon for Energy Storage

Due to its suitable working voltage and high theoretical storage capacity, antimony is considered a promising negative electrode material for lithium-ion batteries (LIBs) and has attracted widespread attention. The volume effect during cycling, however, will cause the antimony anode to undergo a severe structural collapse and a rapid decrease in capacity. Here, a general in situ self-template-assisted strategy is proposed for the rational design and preparation of a series of M Sb (M = Ni, Co, or Fe) nanocomposites with M N C coordination, which are firmly anchored on Swiss-cheese-like nitrogen-doped porous carbon as anodes for LIBs. The large interface pore network structure, the introduction of heteroatoms, and the formation of strong metal N C bonds effectively enhance their electronic conductivity and structural integrity, and provide abundant interfacial lithium storage. The experimental results have proved the high rate performance and excellent cycling stability of antimony-based composite materials. Electrochemical kinetics studies have demonstrated that the increase in capacity during cycling is mainly controlled by the diffusion mechanism rather than the pseudocapacitance contribution. This facile strategy can provide a new pathway for low-cost and high-yield synthesis of Sb-based composites with high performance, and is expected to be applied in other energy-related fields such as sodium-/potassium-ion batteries or electrocatalysis.     

Additive Manufacturing of 3D Aerogels and Porous Scaffolds: A Review

Aerogels are highly porous structures produced by replacing the liquid solvent of a gel with air without causing a collapse in the solid network. Unlike conventional fabrication methods, additive manufacturing (AM) has been applied to fabricate 3D aerogels with customized geometries specific to their applications, designed pore morphologies, multimaterial structures, etc. To date, three major AM technologies (extrusion, inkjet, and stereolithography) followed by a drying process have been proposed to additively manufacture 3D functional aerogels. 3D-printed aerogels and porous scaffolds showed great promise for a variety of applications, including tissue engineering, electrochemical energy storage, controlled drug delivery, sensing, and soft robotics. In this review, the details of steps included in the AM of aerogels and porous scaffolds are discussed, and a general frame is provided for AM of those. Then, the different postprinting processes are addressed to achieve the porosity (after drying); and mechanical strength, functionality, or both (after postdrying thermal or chemical treatments) are provided. Furthermore, the applications of the 3D-printed aerogels/porous scaffolds made from a variety of materials are also highlighted. The review is concluded with the current challenges and an outlook for the next generation of 3D-printed aerogels and porous scaffolds.     

Wood‐Derived Materials for Advanced Electrochemical Energy Storage Devices

Over the past decade, wood‐derived materials have attracted enormous interest for both fundamental research and practical applications in various functional devices. In addition to being renewable, environmentally benign, naturally abundant, and biodegradable, wood‐derived materials have several unique advantages, including hierarchically porous structures, excellent mechanical flexibility and integrity, and tunable multifunctionality, making them ideally suited for efficient energy storage and conversion. In this article, the latest advances in the development of wood‐derived materials are discussed for electrochemical energy storage systems and devices (e.g., supercapacitors and rechargeable batteries), highlighting their micro/nanostructures, strategies for tailoring the structures and morphologies, as well as their impact on electrochemical performance (energy and power density and long‐term durability). Furthermore, the scientific and technical challenges, together with new directions of future research in this exciting field, are also outlined for electrochemical energy storage applications.     

MoS2‐Quantum‐Dot‐Interspersed Li4Ti5O12 Nanosheets with Enhanced Performance for Li‐ and Na‐Ion Batteries

Rational nanoscale surface engineering of electroactive nanoarchitecture is highly desirable, since it can both secure high surface‐controlled energy storage and sustain the structural integrity for long‐time and high‐rate cycling. Herein, ultrasmall MoS₂ quantum dots (QDs) are exploited as surface sensitizers to boost the electrochemical properties of Li₄Ti₅O₁₂ (LTO). The LTO/MoS₂ composite is prepared by anchoring 2D LTO nanosheets with ultrasmall MoS₂ QDs using a simple and effective assembly technique. Impressively, such 0D/2D heterostructure composites possess enhanced surface‐controlled Li/Na storage behavior. This unprecedented Li/Na storage process provides a LTO/MoS₂ composite with outstanding Li/Na storage properties, such as high capacity and high‐rate capability as well as long‐term cycling stability. As anodes in Li‐ion batteries, the materials have a stable specific capacity of 170 mAhg^?1 after 20 cycles and are able to retain 94.1% of this capacity after 1000 cycles, i.e., 160 mAhg^?1, at a high rate of 10 C. Due to these impressice performance, the presented 0D/2D heterostructure has great potential in high‐performance LIBs and sodium‐ion batteries.     

硅基量子点的制备及其发光特性

硅基光电子学无疑是今后光电子学发展的方向，这就要求硅基材料能够满足发光器件的要求，从而达到光电集成的目的。因为硅体具有非直接带隙的特点，共发光效率低，所以利用硅基低维量子结构，尤其是量子点结构提高硅基材料的发光性能一直是国内外本领域的一个研究特点。本文对近年来硅基量子点的制备及发光特性研究所取得的进展和结果进行了总结和评述，并对今后的发展提出了看法。