石墨炔在锂/钠离子电池负极中的应用

二维石墨炔优异的物理和化学性质受到了广泛的关注。近几年,与石墨炔相关的理论、合成和应用研究快速发展,并取得显著成果。基于石墨炔独特的制备方式与可控的分子结构,其已经在很多传统的研究领域展现出潜力,也在一些新兴的研究方向上产生重要影响,表明石墨炔的研究正逐渐成为一个非常热门研究领域。而石墨炔在电化学储能方面的研究越来越多,文章概述了石墨炔与电化学储能相关的优异特性,总结了石墨炔的常规制备方法,重点讨论了在低温制备优势下石墨炔家族成员的迅速壮大和相应石墨炔新成员独特结构对电化学储锂和储钠行为的影响。     

A Self‐Healing Aqueous Lithium‐Ion Battery

Flexible lithium‐ion batteries are critical for the next‐generation electronics. However, during the practical application, they may break under deformations such as twisting and cutting, causing their failure to work or even serious safety problems. A new family of all‐solid‐state and flexible aqueous lithium ion batteries that can self‐heal after breaking has been created by designing aligned carbon nanotube sheets loaded with LiMn₂O₄ and LiTi₂(PO₄)₃ nanoparticles on a self‐healing polymer substrate as electrodes, and a new kind of lithium sulfate/sodium carboxymethylcellulose serves as both gel electrolyte and separator. The specific capacity, rate capability, and cycling performance can be well maintained after repeated cutting and self‐healing. These self‐healing batteries are demonstrated to be promising for wearable devices.     

Molecularly Tailored Lithium–Arene Complex Enables Chemical Prelithiation of High‐Capacity Lithium‐Ion Battery Anodes

Prelithiation is of great interest to Li‐ion battery manufacturers as a strategy for compensating for the loss of active Li during initial cycling of a battery, which would otherwise degrade its available energy density. Solution‐based chemical prelithiation using a reductive chemical promises unparalleled reaction homogeneity and simplicity. However, the chemicals applied so far cannot dope active Li in Si‐based high‐capacity anodes but merely form solid–electrolyte interphases, leading to only partial mitigation of the cycle irreversibility. Herein, we show that a molecularly engineered Li–arene complex with a sufficiently low redox potential drives active Li accommodation in Si‐based anodes to provide an ideal Li content in a full cell. Fine control over the prelithiation degree and spatial uniformity of active Li throughout the electrodes are achieved by managing time and temperature during immersion, promising both fidelity and low cost of the process for large‐scale integration.     

Elastic and Wearable Wire‐Shaped Lithium‐Ion Battery with High Electrochemical Performance

A stretchable wire‐shaped lithium‐ion battery is produced from two aligned multi‐walled carbon nanotube/lithium oxide composite yarns as the anode and cathode without extra current collectors and binders. The two composite yarns can be well paired to obtain a safe battery with superior electrochemical properties, such as energy densities of 27 Wh kg^?1 or 17.7 mWh cm^?3 and power densities of 880 W kg^?1 or 0.56 W cm^?3, which are an order of magnitude higher than the densities reported for lithium thin‐film batteries. These wire‐shaped batteries are flexible and light, and 97 % of their capacity was maintained after 1000 bending cycles. They are also very elastic as they are based on a modified spring structure, and 84 % of the capacity was maintained after stretching for 200 cycles at a strain of 100 %. Furthermore, these novel wire‐shaped batteries have been woven into lightweight, flexible, and stretchable battery textiles, which reveals possible large‐scale applications.     

Bismuth Nanoparticles Embedded in Carbon Spheres as Anode Materials for Sodium/Lithium‐Ion Batteries

Sodium‐ion batteries (SIBs) are regarded as an attractive alternative to lithium‐ion batteries (LIBs) for large‐scale commercial applications, because of the abundant terrestrial reserves of sodium. Exporting suitable anode materials is the key to the development of SIBs and LIBs. In this contribution, we report on the fabrication of Bi@C microspheres using aerosol spray pyrolysis technique. When used as SIBs anode materials, the Bi@C microsphere delivered a high capacity of 123.5 mAh g^?1 after 100 cycles at 100 mA g^?1. The rate performance is also impressive (specific capacities of 299, 252, 192, 141, and 90 mAh g^?1 are obtained under current densities of 0.1, 0.2, 0.5, 1, and 2 A g^?1, respectively). Furthermore, the Bi@C microsphere also proved to be suitable LIB anode materials. The excellent electrochemical performance for both SIBs and LIBs can attributed to the Bi@C microsphere structure with Bi nanoparticles uniformly dispersed in carbon spheres.     

Solvated Graphene Frameworks as High‐Performance Anodes for Lithium‐Ion Batteries

A solvent‐exchange approach for the preparation of solvated graphene frameworks as high‐performance anode materials for lithium‐ion batteries is reported. The mechanically strong graphene frameworks exhibit unique hierarchical solvated porous networks and can be directly used as electrodes with a significantly improved electrochemical performance compared to unsolvated graphene frameworks, including very high reversible capacities, excellent rate capabilities, and superior cycling stabilities.     

Multiple Active Sites: Lithium Storage Mechanism of Cu‐TCNQ as an Anode Material for Lithium‐Ion Batteries

Recently, carboxylate metal‐organic framework (MOF) materials were reported to perform well as anode materials for lithium‐ion batteries (LIBs); however, the presumed lithium storage mechanism of MOFs is controversial. To gain insight into the mechanism of MOFs as anode materials for LIBs, a self‐supported Cu‐TCNQ (TCNQ: 7,7,8,8‐tetracyanoquinodimethane) film was fabricated via an in situ redox routine, and directly used as electrode for LIBs. The first discharge and charge specific capacities of the self‐supported Cu‐TCNQ electrode are 373.4 and 219.4 mAh g^?1, respectively. After 500 cycles, the reversible specific capacity of Cu‐TCNQ reaches 280.9 mAh g^?1 at a current density of 100 mA g^?1. Mutually validated data reveal that the high capacity is ascribed to the multiple‐electron redox conversion of both metal ions and ligands, as well as the reversible insertion and desertion of Li⁺ ions into the benzene rings of ligands. This work raises the expectation for MOFs as electrode materials of LIBs by utilizing multiple active sites and provides new clues for designing improved electrode materials for LIBs.     

MnO@Carbon Core–Shell Nanowires as Stable High‐Performance Anodes for Lithium‐Ion Batteries

A facile method is presented for the large‐scale preparation of rationally designed mesocrystalline MnO@carbon core–shell nanowires with a jointed appearance. The nanostructures have a unique arrangement of internally encapsulated highly oriented and interconnected MnO nanorods and graphitized carbon layers forming an external coating. Based on a comparison and analysis of the crystal structures of MnOOH, Mn₂O₃, and MnO@C, we propose a sequential topotactic transformation of the corresponding precursors to the products. Very interestingly, the individual mesoporous single‐crystalline MnO nanorods are strongly interconnected and maintain the same crystallographic orientation, which is a typical feature of mesocrystals. When tested for their applicability to Li‐ion batteries (LIB), the MnO@carbon core–shell nanowires showed excellent capacity retention, superior cycling performance, and high rate capability. Specifically, the MnO@carbon core–shell nanostructures could deliver reversible capacities as high as 801 mA h g^?1 at a high current density of 500 mA g^?1, with excellent electrochemical stability after testing over 200 cycles, indicating their potential application in LIBs. The remarkable electrochemical performance can mainly be attributed to the highly uniform carbon layer around the MnO nanowires, which is not only effective in buffering the structural strain and volume variations of anodes during repeated electrochemical reactions, but also greatly enhances the conductivity of the electrode material. Our results confirm the feasibility of using these rationally designed composite materials for practical applications. The present strategy is simple but very effective, and appears to be sufficiently versatile to be extended to other high‐capacity electrode materials with large volume variations and low electrical conductivities.     

h‐BN Nanosheets as 2D Substrates to Load 0D Fe3O4 Nanoparticles: A Hybrid Anode Material for Lithium‐Ion Batteries

h‐BN, as an isoelectronic analogue of graphene, has improved thermal mechanical properties. Moreover, the liquid‐phase production of h‐BN is greener since harmful oxidants/reductants are unnecessary. Here we report a novel hybrid architecture by employing h‐BN nanosheets as 2D substrates to load 0D Fe₃O₄ nanoparticles, followed by phenol/formol carbonization to form a carbon coating. The resulting carbon‐encapsulated h‐BN@Fe₃O₄ hybrid architecture exhibits synergistic interactions: 1) The h‐BN nanosheets act as flexible 2D substrates to accommodate the volume change of the Fe₃O₄ nanoparticles; 2) The Fe₃O₄ nanoparticles serve as active materials to contribute to a high specific capacity; and 3) The carbon coating not only protects the hybrid architecture from deformation but also keeps the whole electrode highly conductive. The synergistic interactions translate into significantly enhanced electrochemical performances, laying a basis for the development of superior hybrid anode materials.     

Oxygen-Vacancy-Abundant Ferrites on N-Doped Carbon Nanosheets as High-Performance Li-Ion Battery Anodes

Transition metal oxides, as one of the most promising anode materials for lithium-ion batteries, often suffer from poor electronic conductivity and serious structural collapse. In this work, oxygen-vacancy-abundant CoFe₂O₄ and NiFe₂O₄ deposited on N-doped carbon nanosheets are designed and fabricated through a calcination procedure and a solvothermal strategy using Zn-hexamine coordination frameworks as precursors. The as-prepared NC@CoFe₂O₄ and NC@NiFe₂O₄ hybrids display improved cycle performances and rate capacities compared with CoFe₂O₄, NiFe₂O₄, and Fe₂O₃. The enhanced lithium storage performances of NC@CoFe₂O₄ and NC@NiFe₂O₄ are attributed to the oxygen vacancies and conductive N-doped carbon nanosheets, which increase the electronic conductivity and electrochemical reaction kinetics. The synthetic process in this work provides a new perspective for designing other high-performance transition metal oxide anodes.     

Unveiling the Advances of Nanostructure Design for Alloy‐Type Potassium‐Ion Battery Anodes via In Situ TEM

Nanostructure design and in situ transmission electron microscopy (TEM) are combined to demonstrate Sb‐based nanofibers composed of bunched yolk–shell building units as a significantly improved anode for potassium‐ion batteries (PIBs). Particularly, a metal–organic frameworks (MOFs)‐engaged electrospinning strategy coupled to a confined ion‐exchange followed by a subsequent thermal reduction is proposed to fabricate yolk–shell Sb@C nanoboxes embedded in carbon nanofibers (Sb@CNFs). In situ TEM analysis reveals that the inner Sb nanoparticles undergo a significant volume expansion/contraction during the alloying/dealloying processes, while the void space can effectively relieve the overall volume change, and the plastic carbon shell maintains the structural integrity of electrode material. This work provides an important reference for the application of advanced characterization techniques to guide the optimization of electrode material design.     

High‐Loading Nano‐SnO2 Encapsulated in situ in Three‐Dimensional Rigid Porous Carbon for Superior Lithium‐Ion Batteries

Tin oxide nanoparticles (SnO₂ NPs) have been encapsulated in situ in a three‐dimensional ordered space structure. Within this composite, ordered mesoporous carbon (OMC) acts as a carbon framework showing a desirable ordered mesoporous structure with an average pore size (≈6 nm) and a high surface area (470.3 m² g^?1), and the SnO₂ NPs (≈10 nm) are highly loaded (up to 80 wt %) and homogeneously distributed within the OMC matrix. As an anode material for lithium‐ion batteries, a SnO₂@OMC composite material can deliver an initial charge capacity of 943 mAh g^?1 and retain 68.9 % of the initial capacity after 50 cycles at a current density of 50 mA g^?1, even exhibit a capacity of 503 mA h g^?1 after 100 cycles at 160 mA g^?1. In situ encapsulation of the SnO₂ NPs within an OMC framework contributes to a higher capacity and a better cycling stability and rate capability in comparison with bare OMC and OMC ex situ loaded with SnO₂ particles (SnO₂/OMC). The significantly improved electrochemical performance of the SnO₂@OMC composite can be attributed to the multifunctional OMC matrix, which can facilitate electrolyte infiltration, accelerate charge transfer, and lithium‐ion diffusion, and act as a favorable buffer to release reaction strains for lithiation/delithiation of the SnO₂ NPs.     

A New Anode for Lithium‐Ion Batteries Based on Single‐Walled Carbon Nanotubes and Graphene: Improved Performance through a Binary Network Design

Carbon nanomaterials, especially graphene and carbon nanotubes, are considered to be favorable alternatives to graphite‐based anodes in lithium‐ion batteries, owing to their high specific surface area, electrical conductivity, and excellent mechanical flexibility. However, the limited number of storage sites for lithium ions within the sp²‐carbon hexahedrons leads to the low storage capacity. Thus, rational structure design is essential for the preparation of high‐performance carbon‐based anode materials. Herein, we employed flexible single‐walled carbon nanotubes (SWCNTs) with ultrahigh electrical conductivity as a wrapper for 3D graphene foam (GF) by using a facile dip‐coating process to form a binary network structure. This structure, which offered high electrical conductivity, enlarged the electrode/electrolyte contact area, shortened the electron‐/ion‐transport pathways, and allowed for efficient utilization of the active material, which led to improved electrochemical performance. When used as an anode in lithium‐ion batteries, the SWCNT‐GF electrode delivered a specific capacity of 953 mA h g^?1 at a current density of 0.1 A g^?1 and a high reversible capacity of 606 mA h g^?1 after 1000 cycles, with a capacity retention of 90 % over 1000 cycles at 1 A g^?1 and 189 mA h g^?1 after 2200 cycles at 5 A g^?1.     

One‐Step Solvothermal Synthesis of Single‐Crystalline TiOF2 Nanotubes with High Lithium‐Ion Battery Performance

Single‐crystalline TiOF₂ nanotubes were prepared by a one‐step solvothermal method. The nanotubes are rectangular in shape with a length of 2–3 μm, width of 200–300 nm, and wall thickness of 40–60 nm. The formation of TiOF₂ nanotubes is directly driven by the interaction between TiF₄ and oleic acid in octadecane to form the 1D nanorods, and this is followed by a mass diffusion process to form the hollow structures. The synthesis approach can be extended to grow TiOF₂ nanoparticles and nanorods. Compared with TiO₂, which is the more commonly considered anode material in lithium‐ion batteries, TiOF₂ has the advantages of a lower Li‐intercalation voltage (e.g., to help increase the total voltage of the battery cell) and higher specific capacities. The TiOF₂ nanotubes showed good Li‐storage properties with high specific capacities, stable cyclabilities, and good rate capabilities.     

Electrospun Cu/Sn/C Nanocomposite Fiber Anodes with Superior Usable Lifetime for Lithium‐ and Sodium‐Ion Batteries

Cu/Sn/C composite nanofibers were synthesized by using dual‐nozzle electrospinning and subsequent carbonization. The composite nanofibers are a homogeneous amorphous matrix comprised of Cu, Sn, and C with a trace of crystalline Sn. The Li‐ and Na‐ion storage performance of the Cu/Sn/C fiber electrodes were investigated by using cyclic voltammetry, galvanostatic cycling, and electrochemical impedance spectroscopy. Excellent, stable cycling performance indicates capacities of 490 and 220 mA h g^?1 for Li‐ion (600 cycles) and Na‐ion (200 cycles) batteries, respectively. This is a significant improvement over other reported Sn/C nanocomposite devices. These superior electrochemical properties could be attributed to the advantages of incorporating one‐dimensional nanostructures into the electrodes, such as short electron diffusion lengths, large specific surface areas, ideal homogeneous structures for buffering volume changes, and better electronic conductivity that results from the amorphous copper and carbon matrix.     

Advanced High‐Voltage Aqueous Lithium‐Ion Battery Enabled by “Water‐in‐Bisalt” Electrolyte

A new super‐concentrated aqueous electrolyte is proposed by introducing a second lithium salt. The resultant ultra‐high concentration of 28 m led to more effective formation of a protective interphase on the anode along with further suppression of water activities at both anode and cathode surfaces. The improved electrochemical stability allows the use of TiO₂ as the anode material, and a 2.5 V aqueous Li‐ion cell based on LiMn₂O₄ and carbon‐coated TiO₂ delivered the unprecedented energy density of 100 Wh kg^?1 for rechargeable aqueous Li‐ion cells, along with excellent cycling stability and high coulombic efficiency. It has been demonstrated that the introduction of a second salts into the “water‐in‐salt” electrolyte further pushed the energy densities of aqueous Li‐ion cells closer to those of the state‐of‐the‐art Li‐ion batteries.     

晶态Li12Si7锂离子电池负极材料的电化学性能研究

通过加热摩尔比为12:7的LiH/Si球磨混合物,避免了Li与Si之间巨大的熔点差异,成功制备了晶态Li₁₂Si₇合金,研究了其电化学性能和储锂机制. 发现Li₁₂Si₇在0.02 ~ 0.6 V的嵌脱锂过程中,只发生晶胞体积的变化,而不产生相变,呈现出明显的固溶储锂机制. 该固溶储锂机制的存在,有效抑制了Si基负极材料嵌脱锂过程中由于相变导致的体积效应,使得晶态Li₁₂Si₇在0.02 ~ 0.6 V电压范围内具有显著改善的电化学性能,其首次库伦效率高达100%,30次循环后的可逆容量保持率约为74%,分别优于相同条件下原始Si电极的55%和37%.     

Lithium Germanate (Li2GeO3): A High‐Performance Anode Material for Lithium‐Ion Batteries

A simple, cost‐effective, and easily scalable molten salt method for the preparation of Li₂GeO₃ as a new type of high‐performance anode for lithium‐ion batteries is reported. The Li₂GeO₃ exhibits a unique porous architecture consisting of micrometer‐sized clusters (secondary particles) composed of numerous nanoparticles (primary particles) and can be used directly without further carbon coating which is a common exercise for most electrode materials. The new anode displays superior cycling stability with a retained charge capacity of 725 mAh g^?1 after 300 cycles at 50 mA g^?1. The electrode also offers excellent rate capability with a capacity recovery of 810 mAh g^?1 (94 % retention) after 35 cycles of ascending steps of current in the range of 25–800 mA g^?1 and finally back to 25 mA g^?1. This work emphasizes the importance of exploring new electrode materials without carbon coating as carbon‐coated materials demonstrate several drawbacks in full devices. Therefore, this study provides a method and a new type of anode with high reversibility and long cycle stability.     

Integration of Graphite and Silicon Anodes for the Commercialization of High‐Energy Lithium‐Ion Batteries

Silicon is considered a most promising anode material for overcoming the theoretical capacity limit of carbonaceous anodes. The use of nanomethods has led to significant progress being made with Si anodes to address the severe volume change during (de)lithiation. However, less progress has been made in the practical application of Si anodes in commercial lithium‐ion batteries (LIBs). The drastic increase in the energy demands of diverse industries has led to the co‐utilization of Si and graphite resurfacing as a commercially viable method for realizing high energy. Herein, we highlight the necessity for the co‐utilization of graphite and Si for commercialization and discuss the development of graphite/Si anodes. Representative Si anodes used in graphite‐blended electrodes are covered and a variety of strategies for building graphite/Si composites are organized according to their synthetic methods. The criteria for the co‐utilization of graphite and Si are systematically presented. Finally, we provide suggestions for the commercialization of graphite/Si combinations.