High-performance Anode Materials For Lithium-ion Batteries Research Articles

A Review of Nanocarbon-Based Anode Materials for Lithium-Ion Batteries

Renewable and non-renewable energy harvesting and its storage are important components of our everyday economic processes. Lithium-ion batteries (LIBs), with their rechargeable features, high open-circuit voltage, and potential large energy capacities, are one of the ideal alternatives for addressing that endeavor. Despite their widespread use, improving LIBs’ performance, such as increasing energy density demand, stability, and safety, remains a significant problem. The anode is an important component in LIBs and determines battery performance. To achieve high-performance batteries, anode subsystems must have a high capacity for ion intercalation/adsorption, high efficiency during charging and discharging operations, minimal reactivity to the electrolyte, excellent cyclability, and non-toxic operation. Group IV elements (Si, Ge, and Sn), transition-metal oxides, nitrides, sulfides, and transition-metal carbonates have all been tested as LIB anode materials. However, these materials have low rate capability due to weak conductivity, dismal cyclability, and fast capacity fading owing to large volume expansion and severe electrode collapse during the cycle operations. Contrarily, carbon nanostructures (1D, 2D, and 3D) have the potential to be employed as anode materials for LIBs due to their large buffer space and Li-ion conductivity. However, their capacity is limited. Blending these two material types to create a conductive and flexible carbon supporting nanocomposite framework as an anode material for LIBs is regarded as one of the most beneficial techniques for improving stability, conductivity, and capacity. This review begins with a quick overview of LIB operations and performance measurement indexes. It then examines the recently reported synthesis methods of carbon-based nanostructured materials and the effects of their properties on high-performance anode materials for LIBs. These include composites made of 1D, 2D, and 3D nanocarbon structures and much higher Li storage-capacity nanostructured compounds (metals, transitional metal oxides, transition-metal sulfides, and other inorganic materials). The strategies employed to improve anode performance by leveraging the intrinsic features of individual constituents and their structural designs are examined. The review concludes with a summary and an outlook for future advancements in this research field.

Polyvinylpyrrolidone-assisted sol–gel synthesis of efficient Li2TiSiO5/C composite anodes for Li-Ion batteries

This study presents the process of developing an effective anode material for lithium-ion batteries (LIBs) by usage of Li2TiSiO5 coated with a thin layer of carbon (LTSO/C). The material was prepared through a sol–gel method, where varying amounts of polyvinylpyrrolidone (PVP) were used as a carbon source during the synthesis process. The physicochemical analysis of the LTSO/C samples indicates that as the amount of PVP used during sol–gel synthesis increases, the particle diameter of LTSO decreases. Furthermore, the analysis shows that a thin amorphous carbon layer is deposited on the LTSO surfaces, along with additional carbon networks between the LTSO particles. Based on the electrochemical analysis conducted to optimize the amount of PVP during synthesis, the resulting LTSO/C composite electrode synthesized with 1 g of PVP exhibits a specific capacity of 274.5 mAh·g−1 at 0.1C after 150 cycles, which is quite close to the theoretical capacity. In addition, this LTSO/C electrode demonstrates exceptional electrochemical performance when operated at high rates, surpassing a discharge capacity of 170 mAh g−1 up to 2C. Therefore, the LTSO/C is an excellent choice for high-performance anode material in LIBs.

Robust nitrogen-doped porous carbon encapsulated NiCo2S4 nanodecahedrons for enhanced lithium storage

Transition metal sulfides (TMSs) are attractive anode materials for lithium-ion batteries (LIBs) due to their cost effectiveness, impressive redox properties, and high specific capacity. Among them, NiCo2S4 stands out with a substantial theoretical capacity of 703 mAh g−1 and a high electronic conductivity of 1.25 × 106 S m−1, making it a strong candidate for LIBs. However, NiCo2S4 experiences volume changes and mechanical stress during long-term cycling, leading to structural degradation and rapid capacity decay, which hinders its application. To address these issues, we have developed dodecahedral NiCo2S4 embedded within a nitrogen-doped porous carbon structure (NiCo2S4/NC). The optimal NiCo2S4/NC-300 material exhibits minimum charge transfer resistance, maximum pseudo-capacitive contribution, and exceptional lithium storage performance. At 0.1 A g−1, NiCo2S4/NC-300 exhibits an initial discharge/charge specific capacity of 1730.1/949.4 mAh g−1 and retains a discharge capacity of 454.4 mAh g−1 after 100 cycles. Even at 0.5 A g−1, it delivers an initial discharge/charge capacity of 1301.1/540.1 mAh g−1 with a capacity retention of 81.2 % after 500 cycles. This study presents significant potential for NiCo2S4/NC as a high-performance anode material for LIBs, providing new strategies and insights into the mechanisms for enhancing the performance of TMS-based bimetallic anode materials.

A Strategy for Anode Recovery and Upgrading by In Situ Growth of Iron-Based Oxides on Microwave-Puffed Graphite.

Faced with the increasing volume of retired lithium-ion batteries (LIBs), recycling and reusing the spent graphite (SG) is of great significance for resource sustainability. Here, a facile method for transforming the SG into a carbon framework as well as loading Fe2O3 to form a composite anode with a sandwich structure is proposed. Taking advantage of the fact that the layer spacing of the spent graphite naturally expands, impurities and intercalants are eliminated through microwave thermal shock to produce microwave-puffed graphite (MPG) with a distinct three-dimensional structure. Based on the mechanism of microwave-induced gasification intercalation, a Fe2O3-MPG intercalation compound (Fe2O3-MPGIC) anode material was constructed by introducing iron precursors between the framework layers and subsequently converting them into Fe2O3 through annealing. The Fe2O3-MPGIC anode exhibits a high reversible capacity of 1000.6 mAh g-1 at 200 mA g-1 after 100 cycles and a good cycling stability of 504.4 mAh g-1 at 2000 mA g-1 after 500 cycles. This work can provide a reference for the feasible recycling of SG and development of high-performance anode materials for LIBs.

Insight into graphene/boron arsenide heterostructure used for high-performance lithium-ion battery anode materials: The first principles study

Two-dimensional (2D) van der Waals (vdW) heterostructures demonstrate potential applications in Lithium-ion batteries (LIBs) characterized by their elevated energy storage capacity and extended operational longevity as anode materials. The structures and electronic properties of graphene/boron arsenide (Gr/BAs) heterostructures, along with the adsorption and migration of lithium (Li) atoms within the structures, are methodically analyzed through first-principles studies underpinned by density functional theory. Our calculations indicate the metallic Gr/BAs heterostructures have the structural stability, where their mechanical strength is confirmed from the elastic constant. Its diffusion barrier of Li atoms (0.25 eV) is superior among similar anode materials. The Li atoms' diffusion coefficient within the Gr/BAs heterostructure at 300 K (1.27 × 10−10 m2/s) exceeds that observed in Gr (2.0×10−11 m2/s). Besides, the presence of Gr assists in maintaining the open-circuit voltage (OCV) of Gr/BAs heterostructures in the range of 0-1 V. The theoretical specific capacity of proposed heterostructure reaches 920 mAh/g. The present calculations suggest that the Gr/BAs heterostructure could serve effectively as an anode in LIBs due to its excellent electrical conductivity, small diffusion barriers and appropriate open-circuit voltage.

Research Trends of Transition Metal Carbonate for Lithium-Ion Batteries

Transition Metal Carbonates (TMCs) have emerged as promising candidates for advancing the performance of lithium-ion batteries (LIBs), driven by the increasing demand for high energy and power density in applications such as electric vehicles. This review paper provides a comprehensive overview of the potential of TMCs as anode materials for LIBs, focusing on their unique electrochemical properties and mechanisms. TMCs offer advantages such as eco-friendliness, low cost, and high capacity compared to traditional graphite anodes. Their electrochemical stability, achieved through redox reactions of transition metals, enables capacities exceeding theoretical limits. However, challenges including volumetric expansion and low electrical conductivity during cycling hinder their rate performance and cycling stability. This paper discusses ongoing research efforts to address these challenges, including strategies to mitigate volumetric expansion and enhance electrical conductivity. Furthermore, the lithiophilic nature of TMCs’ transition metals is explored for its role in stabilizing lithium metal surfaces and interfaces within lithium metal batteries, contributing to improved battery performance and safety. Moreover, integrating carbon capture, utilization, and storage (CCUS) technologies into TMC synthesis offers environmentally friendly synthesis methods, aligning with sustainability goals and reducing the carbon footprint of battery manufacturing processes. Overall, this review highlights the potential of TMCs as anode materials for high-performance LIBs, while also addressing challenges and opportunities for further research and development in this promising field.

Computational prediction of two dimensional Mo4BC as promising anode material for lithium-ion batteries

The rising demand for high-capacity energy storage systems drives the hunt for cutting-edge lithium-ion batteries. Herein, calculations based on density functional theory have been performed to investigate the properties of two-dimensional (2D) Mo4BC monolayer as an anode material with high stability and storage capacity. Phonon dispersion and ab initio molecular dynamics (AIMD) simulations were performed to determine the dynamic and thermal stability, respectively. A low diffusion barrier of 0.12 eV supports the ultrahigh ionic mobility of Li ions and cycling capability for this material, which is essential for the fast charging/discharging process. In addition, the Li-ion adsorption on Mo4BC shows a high capacity of about 800 mAhg−1 with an average open circuit voltage (Vocv) of 0.03 V. Comprehensive overview of Mo4BC as high-capacity anode material with negligible low diffusion barrier and metallic character provides a significant contribution towards the advancement of energy storage systems such as lithium-ion batteries (LIBs). Our findings suggest Mo4BC as a promising anode material for high-performance LIBs, thus offering valuable insights for exploring innovative anode materials.

Simple hydrothermal synthesis of HCNFs@CoNiO2 composite material for high-performance anode of lithium-ion batteries

In this study, a novel helical carbon nanofibers@CoNiO2 (HCNFs@CoNiO2) composite was first successfully synthesized by the simple hydrothermal method and utilized as anode materials of lithium-ion batteries (LIBs). CoNiO2 nanoparticles with a particle size of about 6 nm were distributed on the surface of HCNFs matrix. The HCNFs@CoNiO2 anode shows the excellent reversible specific capacity of 808.5 mAh/g after 100 cycles at 200 mA/g, which is about four and twenty times larger than that of HCNFs (193.5 mAh/g) and CoNiO2 (35.4 mAh/g), respectively. The electrochemical performance of HCNFs@CoNiO2 was improved due to the synergistic contribution of HCNFs and CoNiO2. In particular, HCNFs with the unique three-dimensional helical structure improve the conductivity and also provide a strong supporting network space during the volume expansion of CoNiO2 nanoparticles. The present study provides a useful reference for the development of the novel high-performance anode material for LIBs.

MOF-Derived Bimetallic Selenide CoNiSe2 Nanododecahedrons Encapsulated in Porous Carbon Matrix as Advanced Anodes for Lithium-Ion Batteries.

Transition metal selenides have received considerable attention as promising candidates for lithium-ion battery (LIB) anode materials due to their high theoretical capacity and safety characteristics. However, their commercial viability is hampered by insufficient conductivity and volumetric fluctuations during cycling. To address these issues, we have utilized bimetallic metal-organic frameworks to fabricate CoNiSe2/C nanodecahedral composites with a high specific surface area, abundant pore structures, and a surface-coated layer of the carbon-based matrix. The optimized material, CoNiSe2/C-700, exhibited impressive Li+ storage performance with an initial discharge specific capacity of 2125.5 mA h g-1 at 0.1 A g-1 and a Coulombic efficiency of 98% over cycles. Even after 1000 cycles at 1.0 A g-1, a reversible discharge specific capacity of 549.9 mA h g-1 was achieved. The research highlights the synergistic effect of bimetallic selenides, well-defined nanodecahedral structures, stable carbon networks, and the formation of smaller particles during initial cycling, all of which contribute to improved electronic performance, reduced volume change, increased Li+ storage active sites, and shorter Li+ diffusion paths. In addition, the pseudocapacitance behavior contributes significantly to the high energy storage of Li+. These features facilitate rapid charge transfer and help maintain a stable solid-electrolyte interphase layer, which ultimately leads to an excellent electrochemical performance. This work provides a viable approach for fabricating bimetallic selenides as anode materials for high-performance LIBs through architectural engineering and compositional tailoring.

Two-dimensional architecture of N,S-codoped nanocarbon composites embedding few-layer MoS2 for efficient lithium storage.

The exploration and advancement of highly efficient anode materials for lithium-ion batteries (LIBs) are critical to meet the growing demands of the energy storage market. In this study, we present an easily scalable synthesis method for the one-pot formation of few-layer MoS2 nanosheets on a N,S dual-doped carbon monolith with a two-dimensional (2D) architecture, termed MoS2/NSCS. Systematic electrochemical measurements demonstrate that MoS2/NSCS, when employed as the anode material in LIBs, exhibits a high capacity of 681 mA h g-1 at 0.2 A g-1 even after 110 cycles. The exceptional electrochemical performance of MoS2/NSCS can be attributed to its unique porous 2D architecture. The few-layer MoS2 sheets with a large interlayer distance reduce ion diffusion pathways and enhance ion mobility rates. Additionally, the N,S-doped porous carbon matrix not only preserves structural integrity but also facilitates electronic conductivity. These combined factors contribute to the reversible electrochemical activities observed in MoS2/NSCS, highlighting its potential as a promising anode material for high-performance LIBs.

Novel nitrogen-doped carbon-coated SnSe2 based on a post-synthetically modified MOF as a high-performance anode material for LIBs and SIBs.

SnSe2 with high theoretical capacity has been identified as an emerging anode candidate for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). However, the rate performance and cycling performance of this material in practical applications are still limited by unavoidable volume expansion and low conductivity. In this work, we designed and synthesized nitrogen-doped carbon-coated SnSe2/C-N composites using 2-aminoterephthalic acid (C8H7NO4) as a nitrogen-containing compound for modification by hydrothermal and vacuum calcination methods to achieve efficient utilization of active sites and optimization of the electronic structure. The carbon skeleton inherited from the Sn-MOF precursor can effectively improve the electronic conduction properties of SnSe2. N-doping in the Sn-MOF can increase the positive and negative electrostatic potential energy regions on the molecular surface to further improve the electrical conductivity, and effectively reduce the binding energy with Li+/Na+ which was determined by Density Functional Theory (DFT) methods. In addition, the N-doped carbon skeleton also introduces a larger space for Li+/Na+ intercalation and enhances the mechanical properties. In particular, the post-synthetically modified MOF-derived SnSe2/C-N materials exhibit excellent cyclability, with a reversible capacity of 695 mA h g-1 for LIBs and 259 mA h g-1 for SIBs after 100 cycles at 100 mA g-1.

Effects of Secondary Phase on Electrochemical Performance of Co-Free High Entropy Spinel Oxide Anodes for Lithium-Ion Batteries

High entropy oxide (HEO) anode materials have recently gained significant attention in lithium-ion batteries (LIBs) due to their exceptional cycling stability, high specific capacity, and unique adjustable properties. The exclusive feature of HEO allows the use of endless element combinations to create new electrode materials with exciting and unexplored properties. In the context of Li-ion battery anode materials, unlike conventional thinking, where a single-phase high entropy oxide (HEO) is considered sufficient and necessary for delivering good electrochemical performance, we report here that this is not a necessary condition. This study demonstrates the advantages of a secondary phase in HEO. Two types of Co-free high entropy spinel oxide (HESO) are synthesized using solvothermal and hydrothermal methods, resulting in single-phase cubic HESO (HESO (C)) and binary-phase (cubic + tetragonal) HESO (HESO (C+T)), respectively. The secondary tetragonal spinel phase introduces phase boundaries and defects/oxygen vacancies in HESO (C+T), which can improve the redox kinetics and reversibility during electrode lithiation/delithiation. The minor tetragonal phase in the HESO (C+T) anode sustains after cycling, largely reducing the morphology deterioration due to improved reversibility, thus contributing to enhanced cyclability. Density functional theory calculation is performed to assess the phase stability of cubic spinel, tetragonal spinel, and rock-salt structures, and validate the cycling stability of the HEO electrodes upon lithiation/delithiation. This is the first time that the effects of a secondary phase in HEO on the electrochemical properties have been reported. A HESO (C+T)||LiNi0.8Co0.1Mn0.1O2 full cell delivers an energy density of ~610 Wh kg−1, demonstrating a great potential of the HESO (C+T) for use in LIBs. The results provide useful guidelines for designing new high-performance anode materials for LIBs.

Surface-wave-sustained plasma synthesis of graphene@Fe–Si nanoparticles for lithium-ion battery anodes

Silicon encapsulated in conductive layers has proven to be an excellent method for retaining the high capacity of silicon in lithium-ion batteries (LIBs) throughout cycling. This study presents an ultra-fast, single-step, and scalable method for synthesizing graphene@Fe–Si nanoparticles via an atmospheric pressure surface-wave-sustained plasma. The verification of the synthesized nanoparticles, encompassing graphene cladding and silicon nanoparticles encapsulated in iron, was conducted through energy-dispersive x-ray spectroscopy mapping, line scanning in the transmission electron microscopy mode, and high-resolution transmission electron microscopy. Additionally, Raman spectroscopy corroborated the identity of the cladding as graphene. This study provides a viable strategy for the industrial production of anode materials for high-performance LIBs.

N/O/P ternary-doped coal-based hierarchical porous carbon networks for high lithium-ion storage performance

Constructing porous structure and surface modification are effective ways to enhance the Li-ion storage performance of commercial graphite anode for lithium-ion batteries (LIBs). Herein, nitrogen, oxygen and phosphorus ternary-doped coal-based hierarchical porous carbon networks (N/O/P-CCNs) were prepared through liquid oxidation combined with self-assembly method. The N/O/P-CCNs have a three-dimensional porous carbon network structure formed by cross-linking carbon nanosheets with an appropriate specific surface area (321 m2 g−1) and distribution of micro-, meso- and macropore, while the surfaces of carbon nanosheets are doped with nitrogen, oxygen and phosphorus. Due to unique hierarchical porous structure and the synergistic effect of ternary doping, the N/O/P-CCNs anode exhibits excellent Li-ion storage properties with initial reversible capacity of 1079 mAh g−1, which is much higher than that of coal-based graphite anode (382 mAh g−1). Besides, the N/O/P-CCNs anode also has superior rate capability (336 and 275 mAh g−1 at 1.0 and 2.0 A g−1) and cycle stability with a high capacity retention (near 100 % after 100 cycles). The excellent electrochemical performance is not only related to the hierarchical pore structure that can provide efficient channels for lithium-ion transport, but also to the ternary-doping of nitrogen, oxygen and phosphorus that can provide more active sites for lithium-ion storage and enhance conductivity. This work provides a novel and effective design strategy for developing high-performance anode materials for LIBs.

Preparation and electrochemical properties of two novel high entropy spinel oxides (MgTiZnNiFe)3O4 and (CoTiZnNiFe)3O4 by solid state reaction

High entropy oxides (HEOs), a novel class of single-phase inorganic materials with high specific capacity, excellent cycling performance, high structural stability, and super-electronic conductivity, exhibit a wide range of useful properties. It is believed that there is one of the most promising anode materials for lithium-ion batteries (LIBs). Being able to create new electrode materials using an infinite number of elemental combinations thanks to the HEO's distinctive adjustable chemical composition characteristics is advantageous. Herein, two varieties of high entropy spinel oxides, (MgTiZnNiFe)3O4 and (CoTiZnNiFe)3O4 by solid state sintering method, and their material characterization and electrochemical properties were investigated respectively. The outcomes of the experiment demonstrate that the particle size distribution of the two samples is uniform. In the electrochemical test, the capacity is unaffected after 800 cycles at the current density of 1000 mA·g−1, and the two powders exhibit excellent cycle stability and magnification performance. Due to the abundant oxygen vacancies, quick three-dimensional Li+ transport path, and entropy stabilization effect of the spinel structure, all HESOs exhibit exceptional cycle stability and rate capability when serving as the anode of LIBs. The next generation of high-performance lithium-ion battery anode materials may gain from the logical design of high-entropy oxides with a variety of electrochemically active elements and novel structures, according to this research, which proposes a novel method for producing high-entropy energy storage materials.

Mixed-valent Nb boosted the electrochemical performance of K3Nb6P4O26@C anode material for lithium-ion batteries

Niobium-based anode materials have good prospects for application in lithium-ion batteries (LIBs) due to the advantages of high specific capacity and high safety. However, the low electronic conductivity poses the main obstacle that limits its performance at present. Here, a mixed-valent niobium based phosphate, K3Nb6P4O26@C (KNPO@C), was designed and prepared as the anode material for LIBs. The mixed-valent Nb in KNPO provides multi-electron electrochemical reactions and presents an electronic conductivity higher than that of a sole Nb5+-based material. In addition, the three-dimensional (3D) channels in the crystal structure of KNPO facilitate the rapid transport of lithium-ions. KNPO@C anode delivers a high specific capacity of 250 mA h g–1 at 0.1 C and an excellent cycling stability was measured with a capacity retention of 60.7 % after 1000 cycles at 2 C. The charge/discharge mechanism of KNPO@C was systematically investigated by ex-situ XRD and ex-situ XPS. The kinetic information obtained from the cyclic voltammetry (CV) suggests that the pseudocapacitance effect also play an important role in the specific capacity. These results demonstrate the potential of KNPO@C as a practical anode material for high-performance LIBs.

Two-dimensional CrP2 with high specific capacity and fast charge rate for lithium-ion battery

The electrode material is regarded as one of the key factors that determine the performance of lithium-ion batteries (LIBs). However, it is still a challenge to search for an anode material with large capacity, low diffusion barrier, and good stability. In the present work, two new CrP2 monolayers (Pmmn-CrP2 and Pmma-CrP2) are predicted by means of first principles swarm structure search. Our study shows that both the two CrP2 monolayers have high dynamical and thermal stability, as well as excellent electron conductivity. Additionally, Pmmn-CrP2 exhibits a remarkably high storage capacity of 705 mA⋅h⋅g−1 for Li, meanwhile the diffusion energy barrier of Li on the surface of this monolayer is 0.21 eV, ensuring it as a high-performance anode material for LIBs. We hope that our study will inspire researchers to search for new-type two-dimensional (2D) transition metal phosphides for the electrode materials of LIBs.

CoSe nanoparticles in-situ grown in 3D honeycomb carbon for high-performance lithium storage

Although transition metal selenides are considered to be extremely promising anode materials for lithium-ion batteries (LIBs), severe volume changes and low electronic conductivity are their huge and unavoidable challenges. To solve these problems, CoSe nanoparticles in-situ grown on the inner surface of every macropore of 3D honeycomb C is successfully synthesized by three simple steps: dense assembling of polystyrene spheres, calcination and gaseous selenylation. The sizes of CoSe and honeycomb pores are 10–15 nm and 190 nm, respectively. The content of CoSe is 72 wt%. This unique architecture guarantees high electrochemical activity, rapid reaction kinetics and excellent structural stability of CoSe, as identified by cycling and rate performance measurements, various electrochemical kinetics analyses and ex-situ characterization of the cycled electrode material. As a result, the CoSe@honeycomb C anode exhibits extraordinary cycling performance (823.5 mAh g−1 after 200 cycles at 0.5 A g−1, 610.1 mAh g−1 after 250 cycles at 2 A g−1, 247 mAh g−1 after 1500 cycles at 5 A g−1) and exceptional rate capability (261.9 mAh g−1 at 10 A g−1, 1491.4 mAh g−1 at 0.1 A g−1), demonstrating that it is a potential anode material for high-performance LIBs.

Molten salt-assisted valorization of waste PET plastics into nanostructured SnO2@terephthalic acid with excellent Li-ion storage performance

Polyethylene terephthalate (PET) is one of the most widely used plastic materials, and therefore, its clean, efficient and low-cost valorization into high-value materials is of substantial economic and environmental interest. Here, for the first time, the utilization of molten salts for the facile, scalable and fast depolymerization of PET into terephthalic acid (C8H6O4) is reported. It is asserted that the simple heat-treatment of PET in molten KCl-LiCl containing SnCl2 in air leads to the green preparation of nanocrystalline terephthalic acid embedded with SnO2 nanocrystals, with an excellent performance as the anode of lithium ion batteries (LIBs). The structural, morphological, thermal, surface, electrical and electrochemical characteristics of plastic-derived nanocomposites are evaluated by various techniques. The sample prepared at 500 °C (PDN-500) contains 28.3 wt% SnO2, and exhibits an enhanced bulk electrical conductivity of 447.3 S m−1, and an excellent Li-ion storage capacity of 498 mAh g-1 after 500 cycles, corresponding to 1657 mAh per gram of SnO2. This performance is accompanied by an enhanced lithium ions diffusion coefficient of 8.51 × 10−10 cm2 s−1 recorded after 300 cycles, and a capacitive storage contribution of above 42 %. The sustainability of the presented molten salt approach is discussed from two complementary points of view, in terms of the clean conversion of waste plastics into high-performance anode materials for LIBs, as well as the facile and scalable depolymerization of PET, reducing the waste plastics in our environment. This article proposes an efficient and green strategy for the valorization of waste plastics into nanostructured SnO2@terephthalic acid for energy storage applications.

Ordered sandwich silicon quantum dot/Fe3O4/reduced graphene oxide architectures for high-performance lithium-ion batteries

Iron-based oxides are one of the most promising anode materials for lithium-ion batteries (LIBs) because of their high theoretical capacity, low cost, and eco-friendliness. However, its poor cycle stability and low-rate performance limit its wide application. In this work, a novel ordered sandwich-structured nanocomposite consisting of Fe3O4, silicon quantum dots (Si-QDs), and reduced graphene oxide (rGO) is synthesized via a self-assembly approach combined with subsequent annealing. Si-QDs are vital to guide the uniform formation and homogeneous distribution of nano-sized Fe3O4 on the rGO nanosheets. The resultant Si-QDs/Fe3O4/rGO composite possesses a unique ordered sandwich structure, in which Si-QDs and Fe3O4 particles are evenly anchored on rGO nanosheets. Si-QDs/Fe3O4/rGO delivers high specific capacity, outstanding cycling stability, and rate capability. At a current density of 100 mA·g−1, it displays an initial discharge-specific capacity of 1489.6 mAh·g−1 and maintained a specific capacity of 1367.1 mAh·g−1 after 80 cycles. The crucial effect of Si-QDs on the composite's morphology, structure, and electrochemical performances is deeply investigated by corresponding characterizations. The preparation strategy may be introduced in other metal-oxide-based nanocomposites with ordered sandwich structures and points out an ingenious way to design anode materials for high-performance LIBs.