Anode Material Research Articles

Confining Conversion Chemistry in Intercalation Host for Aqueous Batteries.

Conversion-type anode materials with high theoretical capacities play a pivotal role in developing future aqueous rechargeable batteries (ARBs). However, their sustainable applications have long been impeded by the poor cycling stability and sluggish redox kinetics. Here we show that confining conversion chemistry in intercalation host could overcome the above challenges. Using sodium titanates as a model intercalation host, an integrated layered anode material of iron oxide hydroxide-pillared titanate (FeNTO) is demonstrated. The conversion reaction is spatially and kinetically confined within sub-nano interlayer, enabling superlow redox polarization (ca. 4-6 times reduced), ultralong lifespan (up to 8700 cycles) and excellent rate performance. Notably, the charge compensation of interlayer via universal cation intercalation into host endows FeNTO with the capability of operating well in a broad range of aqueous electrolytes (Li+, Na+, K+, Mg2+, Ca2+, etc.). We further demonstrate the large-scale synthesis of FeNTO thin film and powder, and rational design of quasi-solid-state high-voltage ARB pouch cells powering wearable electronics against extreme mechanical abuse. This work demonstrates a powerful confinement means to access disruptive electrode materials for next-generation energy devices.

Zinc Dicyanamide: A Potential High-Capacity Negative Electrode for Li-Ion Batteries.

We demonstrate that the β-polymorph of zinc dicyanamide, Zn[N(CN)2]2, can be efficiently used as a negative electrode material for lithium-ion batteries. Zn[N(CN)2]2 exhibits an unconventional increased capacity upon cycling with a maximum capacity of about 650 mAh·g-1 after 250 cycles at 0.5C, an increase of almost 250%, and then maintaining a large reversible capacity of more than 600 mAh·g-1 for 150 cycles. Such an increased capacity is primarily attributed to the increased level of activity in the conversion reaction. A combination of conversion-type and alloy-type mechanisms is revealed in this anode material via advanced characterization studies and theoretical calculations. This mechanism, observed here for the first time in transition-metal dicyanamides, is probably responsible for the outstanding electrochemical performance. We believe that this study guides the development of new high-capacity anode materials.

A Robust Network Sodium Carboxymethyl Cellulose-Epichlorohydrin Binder for Silicon Anodes in Lithium-Ion Batteries.

Silicon (Si), as an ideal anode component for lithium-ion batteries, is susceptible to substantial volume changes, leading to pulverization and excessive electrolyte consumption, ultimately resulting in a rapid decline in the cycle stability. Herein, a new sodium carboxymethyl cellulose-epichlorohydrin (CMC-ECH) binder featuring a three-dimensional (3D) network cross-linked structure is synthesized by a simple ring-opening reaction, which can effectively bond the Si anode through abundant covalent and hydrogen bonds to mitigate its pulverization. Benefitting from the merits of the CMC-ECH binder, the electrochemical performance is significantly enhanced compared to the CMC binder. The CMC-ECH binder is applied to Si anodes, a specific capacity of 1054.2 mAh g-1 can be maintained at 0.2 C following 200 cycles under an elevated Si mass loading of around 1.0 mg cm-2, and the corresponding capacity retention is 65.6%. In the case of the LiFePO4//Si@CMC-ECH full battery, the cycle stability exhibits a substantial enhancement compared with the LiFePO4//Si@CMC full battery. Furthermore, the CMC-ECH binder demonstrates compatibility with micron-Si anode materials. Based on the above, we have successfully developed a facilely prepared water-based CMC-ECH binder that is suitable for Si and micron-Si anodes in lithium-ion batteries.

Liquid Metal-Modified 3D Cu Foam for Dendrite-Free Sodium Plating.

Sodium metal is regarded as one of the most promising anode materials due to its high theoretical capacity (1166mAhg-1) and low redox potential (-2.714V vs standard hydrogen electrode). However, the practical application of sodium metal is hindered by the formation of dendrites during Na stripping and plating, which can degrade performance and cause potential safety hazards. To address this issue, previous work focuses on leveraging either 3D current collectors or liquid metal modification on current collectors. In this work, both strategies are simultaneously leveraged to design a 3D Cu foam with liquid metal modification (LM@Cu) for dendrite-free sodium plating. The 3D configuration of Cu effectively reduces local current density and evenly distributes electric fields, while the introduction of liquid metal enhances the sodiophilicity of Cu to lower the nucleation barrier for sodium, thereby promoting its uniform plating. As a result, symmetric cells of Na with LM@Cu maintain stable cycling for over 2800h. Additionally, full cells comprising Na-LM@Cu and Na3V2(PO4)3 sustain 97.5% of the capacity upon 1000 cycles, underscoring the great potentiality of liquid metal-mediated 3D current collectors in energy storage.

Multiple heteroatom-doped cobalt sulfoselenide@C yolk-shell microsphere as excellent anode materials for sodium-ion batteries and their conversion reaction mechanism with sodium ions

To address the sluggish reaction kinetics commonly associated with the transition metal chalcogenide anodes in their interaction with alkali metal ions, introducing heterostructures into these materials is proposed as a novel approach. Herein, we introduce a fabrication method for yolk-shell structured microsphere comprising heteroatom-doped cobalt sulfoselenide nanocrystals using a recycled solution. The prepared material demonstrates a composition of sulfur-doped cobalt selenide, forming hetero-anion metal compounds. A detailed study of the reaction mechanism in cobalt sulfoselenide reveals the formation of Na2S/Na2Se heterointerfaces during the conversion reaction, which facilitate a rapid diffusion of Na-ions. Furthermore, heteroatom doping in the cobalt sulfoselenide nanocrystals, induced by cobalt recycling process, leads to the lattice expansion, further enhancing the Na-ion diffusion kinetics. Additionally, through an infiltration of pitch solution and a simple heat-treatment, pitch-derived carbon is coated on the cobalt sulfoselenide nanocrystals. This carbon layer can effectively accommodate the volumetric stress during repeated cycling, enhancing the stability. Consequently, carbon-coated heteroatom-doped cobalt sulfoselenide yolk-shell microsphere anode exhibits stable cycling stability (560 mA h g−1 for 100 cycles at 0.2 A g−1) as well as great rate capability (140 mA h g−1 at 15 A g−1) for sodium-ion batteries (SIBs).

Efficient Regeneration of Graphite from Spent Lithium-Ion Batteries through Combination of Thermal and Wet Metallurgical Approaches

With the large-scale application of lithium-ion batteries (LIBs) in various fields, spent LIBs are considered one of the most important secondary resources. Few studies have focused on recycling anode materials despite their high value. Herein, a new efficient recycling and regeneration method of spent anode materials through the combination of thermal and wet metallurgical approaches and restored graphite performance is presented. Using this method, the lithium recycling ratio from spent anode materials reaches 87%, with no metal impurities detected in the leaching solution. The initial Coulombic efficiency of the recycled graphite (RG) materials is 90.5%, with a reversible capacity of 350.2 mAh/g. Moreover, RG shows better rate performance than commercial graphite. The proposed method is simple and efficient and does not involve toxic substances. Thus, it has high economic value and application potential in graphite recycling from spent LIBs.

Research on Lithium Storage Performance of MoS2/rGO Composites

AbstractMoS2/reduced graphene oxide (MoS2‐I, MoS2/rGO‐II and MoS2/rGO‐V) composites with the mass ratio of MoS2 to GO is 1:1, 2:1 and 5:1, which were used as anode materials for lithium‐ion batteries (LIBs). The electrochemical properties and structure were tested and characterized. In the first cycle charge and discharge, the initial discharge capacity of MoS2/rGO‐II electrode is 821.8 mAh g−1 at 0.1 C, and the first coulomb efficiency is 92.09 %. The capacity attenuation of the second and third cycles is 65 mAh g−1 and 10.1 mAh g−1, respectively. Compared to MoS2 electrode, the attenuation of MoS2/rGO‐II electrode is obviously improved at different rates of 0.1 C, 0.2 C and 0.5 C, so MoS2/rGO‐II electrode shows excellent rate performance. Through the reaction mechanism analysis, it is concluded that most of the oxygen‐containing functional groups on the surface of GO are removed, but the conjugated network of graphene is not fully restored, resulting in the loss of electrical conductivity. However, the results of EIS directly show that rGO can still provide good conductivity for MoS2. Therefore, MoS2/rGO composites have great potential as electrodes for LIBs and broad research and application prospects in the field of energy storage.

Correction to: Si48, SiNT(7, 0), B24N24 and BNNT(7, 0) as Acceptable Anode Materials in Mg-ion Batteries

Correction to: Si48, SiNT(7, 0), B24N24 and BNNT(7, 0) as Acceptable Anode Materials in Mg-ion Batteries

O-Targeted Carbon Hybrid Orbital Conversion to Produce sp2-Rich Closed Pores for Sodium-Storage Hard Carbon.

Biomass-based hard carbon has the advantages of a balanced cost and electrochemical performance, making it the most promising anode material for sodium-ion batteries. However, due to the structural limitations of biomass (such as macropores and impurities), it still faces the problems of low specific capacity and initial Coulombic efficiency (ICE). Herein, an integrated strategy of biomass liquefaction and oxidation treatment is proposed to fabricate hard carbon with low ash content and sp2-rich closed pores. Specifically, liquefaction treatment can break through the inherent constraints of biomass, while oxidation treatment with O-targeted effect can directionally convert C─C/C─O bonds into C═O/O═C─O bonds, which would promote the formation of closed pores and the rearrangement into sp2-carbon within the graphene layer. Moreover, it is well demonstrated that the hard carbon interface rich in sp2 hybridization can induce the generation of an inorganic-rich solid electrolyte interface, contributing to fast ion migration and excellent interfacial stability. As a result, the optimized hard carbon with maximum closed pore volume and sp2/sp3 ratio can exhibit a high capacity of 347.3mAhg-1 at 20mAg-1 with the ICE of 90.5%, and a capacity of 110.4mAhg-1 at 5.0Ag-1 after 10000 cycles.

A 3D conducting scaffold with lithiophilic carbon nanoparticles for stable lithium metal battery anodes

Li metal anode with high capacity, negative potential and low density is regarded as the most promising anode material. Unfortunately, its commercialization is greatly limited by Li dendrites. Here, a 3D carbon paper scaffold with lithiophilic carbon nanoparticles is synthesized as a Li host via the carbonization of metal-organic framework and the doping of oxygen atom. Carbon nanoparticles effectively improve the specific surface area of carbon paper that can low the local current density and provide rich internal spaces for Li reservoir. In addition, the rich lithiophilic groups (such as ZnO, nitrogen atom and oxygen atom) can regulate a uniform Li+ flux and achieve a controllable Li deposition. Based on these structural advantages, uniform nucleation and growth of Li metal have been realized. Especially, the symmetric cell renders an outstanding cyclic stability for 750 h with an ultra-low polarization voltage of 14 mV at 1 mA/cm2. Additionally, the full cell partied with a LiFePO4 cathode displays an initial specific capacity of 138.1 mAh/g, and even maintains 97.7 % capacity retention after 120 cycles at 0.5C. Therefore, this strategy presents a universal approach to construct porous hosts with abundant lithiophilic sites for long-lifespan Li metal batteries.

Ultra-thin SnS2 nanosheets grown on carbon nanofibers with high-performance in sodium-ion energy storage

SnS2 with two-dimensional layered structure has great application promising in the energy storage system due to its super high theoretical capacity. However, the serious volume expansion and low intrinsic conductivity are difficult to meet the commercial application of SnS2 in sodium-ion batteries (SIBs). Herein, SnS2/CNF was successfully prepared by simple electrospinning technique and hydrothermal method. Based on the synergistic effect between ultra-thin nanosheets and carbon nanofibers (CNF), the anode material not only shortened the path of electron transport, but also accelerated the sodium ion reaction kinetics, thus showed outstanding stability and reversibility SIBs. The SnS2/CNF displayed the excellent rate properties (352 mAh g-1 at 5 A g-1) as well as stable long term cycle performance (338 mAh g-1 at 3 A g-1 after 500 cycles). Furthermore, the SnS2/CNF//AC sodium-ion hybrid capacitor (SIHCs) exhibits excellent energy density and power density of 97 Wh kg-1/54 W kg-1. The capacity retention is 81 % after 2500 cycles at 1 A g-1. The SIHCs could light up to 100 LEDs easily, which thus exhibited great practical application potential in energy storage device.

Progress on Copper-Based Anode Materials for Sodium-Ion Batteries.

Fossil fuels have clearly failed to meet people's growing energy needs due to their limited reserves, potential pollution of the environment, and high costs. The development of cleaner, renewable energy sources as well as secondary batteries for energy storage is imminent, in a modern society where energy demand is soaring. Sodium-ion batteries (SIBs) have become the focus of large-scale energy storage systems as a promising alternative to lithium-ion batteries. The development of SIBs relies on the construction of high performance electrode materials. The design of low cost and high performance anode materials is a key link in this regard. Copper-based anodes are characterized by high theoretical capacity, abundant reserves, low cost and environmental friendliness. A variety of copper-based anode materials, which include cobalt oxides, sulfides, selenides and phosphides, have been synthesized and evaluated in the scientific literature for sodium storage. In detail, the preparation methods, response mechanisms, strengths and weaknesses, the relationship between morphology structure and electrochemical performance are discussed, as well as highlighting strategies to improve the electrochemical performance of copper-based anode materials. Finally, we offer our perspective on the challenges and potential for the development of copper-based anodes as a means of developing practical and high performing SIBs.

Functional Binder with Enhanced Chemical Adsorption for Black Phosphorus Anode in Lithium‐Ion Capacitors

AbstractBlack phosphorus (BP) has been recognized as an ideal anode material for fast‐charging lithium (Li)‐ion capacitors (LICs) due to its high theoretical capacity (2596 mAh g−1), appropriate lithiation potential (0.7 V vs Li+/Li) and fast ion diffusion capability. However, large volume change and soluble polyphosphides (LixPs)‐based intermediates during charging‐discharging process seriously deteriorate cycling performance. To address the aforementioned issues, an elaborated design is reported on the binder for BP electrode. The ‐NH2 polar functional group in grafted chitosan (GCS) binder presents strong chemical anchoring effect for both BP and soluble LixPs, achieving superior adhesion force and LixPs constraining capability for enhanced structure integrity of BP electrode. In addition, GCS exhibits strong Li‐ion binding energy that promotes the Li‐ion adsorption at electrode level, leading to a boosted cycle life for BP. As a result, the graphene (G) incorporated BP electrode using GCS binder shows specific capacity of 997.6 mAh g−1 after 400 cycles at 1 A g−1. This study unravels the crucial role of functional groups for binder in high‐performance BP electrode.

Manipulating Interfacial Renovation via In Situ Formed Metal Fluoride Heterogeneous Protective Layer toward Exceptional Durable Sodium Metal Anodes

AbstractSodium metal is regarded as an optimal anode material for high‐energy‐density sodium‐ion batteries (SIBs). However, during the processes of sodium deposition and stripping, the failure of the solid electrolyte interphase (SEI) film leads to the continuous accumulation of inactive sodium, thereby compromising the cycling reversibility of the battery. Here, a novel metal fluoride heterointerface layer is generated and constructed through in situ manipulation of the continuous reaction between TiF4 and metal Na. The reconstructed NaF/TiF3 interface layer, which tightly anchors the sodium metal, effectively suppresses the formation of sodium dendrites during the charge‐discharge process. The highly sodium‐philic TiF3 component exhibits strong binding with Na ions, while NaF reduces the Na+ diffusion energy barrier, significantly enhancing the reaction kinetics. Due to the successful artificial construction of this interface layer, the Na/TiF4 composite electrode demonstrates an exceptional ultra‐long cycling stability of 2370 h in symmetric cells (0.5 mAh cm−2). Density functional theory (DFT) calculations further validate the functionality of each component in the Na/TiF4 protective layer. When paired with NaNi1/3Fe1/3Mn1/3O2 cathode in a pouch cell, it exhibits stability up to 2000 cycles at current densities of 2 C and 4 C, with a maximum energy density output of 483.1 Wh kg−1 (power density: 320.8 W kg−1).

Effect of MnO2 on crystallization behavior and specific capacity of phosphate glass anode

AbstractIn recent years, glass anodes have been widely studied. However, self‐crystallization often occurs during glass preparation, which leads to a reduction in the cycle stability of the glass anode. In this work, SnO–P2O5–MnO2 glass anode materials were prepared using the melt‐quenching method. By increasing the concentration of MnO2, the specific capacity (after 800 cycles) of the glass anode was increased by 62%, from 234.9 to 381.3 mAh g−1. The result indicates that the introduction of MnO2 makes the glass structure more compact and suppresses the glass's ability of self‐crystallization, which is beneficial for the long‐cycle performance of lithium‐ion batteries. In addition, with the introduction of MnO2 in glass, manganese–tin synergistic discharge disperses the internal stress during the alloying process, which further enhances the cycling stability of the glass anode. This research is to propose a new reference for improving the cycle life and specific capacity of glass anode materials.

Batch-Scale Synthesis and Interfacially Enhanced Stability of Silicon Suboxide-Based Anodes toward High-Performance Lithium-Ion Batteries.

SiOx anode materials are among the most promising candidates for next-generation high-energy-density lithium-ion batteries (LIBs). However, their commercial application is hindered by poor conductivity, low initial Coulombic efficiency (ICE), and an unstable solid electrolyte interface. Developing cost-effective SiOx anodes with high electrochemical performance is crucial for advanced LIBs. To tackle these issues, this study utilized APTES as a silicon source and carbon nanotubes (CNTs) as additives to prepare a T-SiOx/C/CNTs composite material with N doping and in situ carbon coating using a "molecular assembly combined with controlled pyrolysis" strategy under mild conditions. The in situ carbon coating, formed by the pyrolysis of organic groups on the molecular precursor, effectively protects the inner SiOx active material. The introduced CNTs enhance electron migration and improve the rigidity of the carbon coating layer. The prelithiated T-SiOx@C/CNTs electrode achieves an ICE of 91.6%, with a specific capacity of 622 mAh g-1 after 400 cycles at 1 A g-1 and 475.8 mAh g-1 after 800 cycles. Full cell tests with commercial NCM811 cathodes further demonstrate the potential of T-SiOx@C/CNTs as a highly promising anode material. This work provides some insights into the rational design of advanced anode materials for LIBs, paving the way for their future development and application.

Antimony nanoparticles encapsulated in interconnected nitrogen-doped carbon nanospheres for high performances PIBs

Antimony (Sb) has attracted significant attention as an anode material for potassium-ion batteries (PIBs) due to its high theoretical capacity and suitable working voltage. However, the severe volume variations of Sb during potassiation/depotassiation process lead to sluggish kinetics and poor cyclic stability for PIBs. In this study, Sb nanoparticles are confined within interconnected N-doped carbon nanospheres (Sb@NC) through an effective carbothermal reduction process. The potassium storage performances and mechanism are elucidated through electrochemical tests combined with ex-XRD analysis. When used as an anode for PIBs, the optimized Sb@NC-2 anode exhibits excellent cycle stability of 463.0 mAh g−1 at 200 mA g−1 over 100 cycles and superior rate capability of 113.4 mAh g−1 at a high current density of 2 A g−1. Besides, a full cell comprising an Sb@NC-2 anode and a PTCDA cathode is also tested to validate the practical feasibility of the anode. Furthermore, Density Functional Theory (DFT) calculations demonstrate that N-doped carbon can enhance the adsorption of K+ and improve the kinetics of electrochemical reactions. Therefore, the unique yolk-shell structure in this study effectively restricts volume expansion and aggregation of Sb particles while facilitating rapid electron/ion transfer. These findings provide a potential alternative anode material for advanced PIBs.

A first-principles research on the properties of two-dimensional penta-BP2 as an anode material for both Na and K ion batteries

The escalating demand for large-scale energy storage solutions has sparked significant interest in metal-ion batteries, particularly in the realm of high-performance anode materials. This work explores the potential of penta-BP2 as an anode material for sodium and potassium-ion batteries through first-principles calculations. The two-dimensional metallic structure of penta-BP2 exhibits favorable electrical conductivity, making it an ideal candidate for anode materials. Theoretical analysis reveals that penta-BP2 can adsorb two layers of Na and three layers of K, resulting in high storage capacities of 1105 and 1473 mAh/g, along with low open-circuit voltages of 0.40 and 0.30 V, respectively. These characteristics enable the production of high energy density in sodium and potassium-ion batteries. Additionally, the material's small Young's modulus and low diffusion energy barriers further establish penta-BP2 as a flexible anode material capable of rapid charge/discharge processes.

Self-Propagating Fabrication of a 3D Graphite@rGO Film Anode for High-performance Potassium-Ion Batteries.

Graphite, with abundant resources and low cost, is regarded as a promising anode material for potassium-ion batteries (PIBs). However, because of the large size of potassium ions, the intercalation/deintercalation of potassium between the interlayers of graphite results in its huge volume expansion, leading to poor cycling stability and rate performance. Herein, a self-propagating reduction strategy is adopted to fabricate a flexible, self-supporting 3D porous graphite@reduced graphene oxide (3D-G@rGO) composite film for PIBs. The 3D porous network can not only effectively mitigate the volume expansion in graphite but also provide numerous active sites for potassium storage as well as allow for electrolyte penetration and rapid ion migration. Therefore, compared to the pristine graphite anode, the flexible 3D-G@rGO film electrode exhibits greatly improved K-storage performance with a reversible capacity of 452.8 mAh g-1 at 0.1 C and a capacity retention rate of 80.4% after 100 cycles. It also presents excellent rate capability with a high specific capacity of 139.1 and 94.2 mAh g-1 maintained at 2 and 5 C, respectively. The proposed self-propagating reduction strategy to construct a three-dimensional self-supporting structure is a viable route to improve the structural stability and potassium storage performance of graphite anodes.

Dual plating zinc foam of three-dimensional reconstruction as a high-flux and stable zinc metal anode for aqueous zinc-ion batteries

The practical utilization of zinc-metal anodes is primarily hindered by the restricted lifespan and diminished Coulombic efficiency (CE) arising from the growth of zinc dendrites and concurrent side reactions. To tackle these challenges, numerous 3D hosts have been thoroughly investigated, although there is still a need to address concerns related to high-flux deposition and electrode corrosion resistance. In a pioneering effort, a double-coated material derived from foamed zinc (denoted as FZn@Cu) has been developed for utilization as an anode in high-performance zinc-metal batteries. FZn@Cu originates from a three-dimensional reconstruction of a zinc electrode (foam Zn) in a porous and layered structure with a dense Cu coating on the surface and a solid CuZn5 at the interface. Experimental observations, density-functional theory calculations and phase-field simulations indicate that zincphilic Cu and CuZn5 can induce homogeneous deposition of Zn. The results show that FZn@Cu has low voltage hysteresis (25.1 mV), long cycling stability (exceeding 1800 h) and the ability to inhibit electrode corrosion. In addition, the full cell based on FZn@Cu composite anode and MnO2 cathode exhibits excellent multiplicity performance and stable cycle life (133.9 mAh g−1 at 1 A g−1 after 1000 cycles). This study introduces an innovative and scalable zinc-based anode material, offering a new strategy for the design of dendrite-free zinc anodes.