Electrode Materials For Lithium-ion Batteries Research Articles

Multilayer-coating process for the synthesis of nickel-silicate composite with high Ni loading as high-rate performance lithium-ion anode material

BackgroundMetal silicates possess several important advantages as electrode materials for lithium-ion batteries (LIBs), including straightforward synthesis, low cost, and high thermal stability. A green synthesis routes that are capable of increasing metal loading and reducing the impact on the environment are required. MethodsA Ni-silicate with a multilayer structure and a Ni/Si molar ratio of 0.25 is first prepared using the co-precipitation method. The as-synthesized product is then repeatedly immersed in a Ni2+ solution to obtain Ni-silicate with the desired Ni contents (Ni/Si molar ratio: 0.50–2.00). Finally, the resulting Ni-silicate is reconstructed by hydrothermal treatment under various temperatures (70 °C, 100 °C, 150 °C) and durations (3 h and 24 h) to obtain Ni-phyllosilicate. The effects of the hydrothermal treatment temperature, hydrothermal time, and Ni/Si ratio on the structure, morphology, and surface area of the Ni-silicate composites are examined. Significant FindingsThe Ni-silicate with a Ni/Si ratio of 1.5 has a reversible capacity of 729 mAhg-1, which exceeds traditional graphite anodes (372 mAhg-1). Furthermore, the material exhibits a capacity retention of up to 80 % as the current density is increased from 0.025 Ag-1 to 0.5 Ag-1. Thus, the synthesized Ni-silicate composite is a promising candidate material for LIB anode.

DFT and AIMD studies of SnFe2O4 as a promising anode for Li-ion batteries

Tin ferrite (SnFe2O4) is considered as a perspective lithium ion battery anode, owing to its low cost, large theoretical capacity, low toxicity, structural stability, and easy synthesis method. Prior research has been done on the performance of lithium storage in SnFe2O4. However, the electrochemical processes that take place during the lithiation-delithiation cycle of LIBs have not been explained in depth yet. In order to understand the discharge mechanism in the LixSnFe2O4 anode (x = 0 to 2), we systematically investigated its electrochemical characteristics, structural and electronic properties, average formation energies, open-circuit voltages, diffusion coefficient, and volume expansion using density functional theory. According to our calculations, an increase in Li concentration x up to 1.125 leads to enhanced stability of the LixSnFe2O4 systems. During this process, Li+ ions prefer to be intercalated at the octahedral 16c sites, inducing the displacement of Sn2+ ions from tetrahedral sites 8a to 16c and 48f sites. However, for 1.125 < x < 2, lithium ions tend to occupy the less stable sites 48f , which reduces the stability of LixSnFe2O4 systems.Additionally, the calculated lithium intercalation voltage for full lithiation Li1.125SnFe2O4 is equal to 1.5 V, and the distortion of the LixSnFe2O4 system occurs at a voltage of 0.75 V, which is in well agreement with experimental results. The Li-coefficient diffusion on SnFe2O4 at 300 K is calculated by ab initio molecular dynamic simulation and equal to 8.22 × 10−8 cm2/s, which indicates the excellent mobility of Li ions in SnFe2O4. Considering all these results, we can suggest SnFe2O4 as a promising negative electrode material for lithium-ion batteries.

Unveiling electrochemical insights of lithium manganese oxide cathodes from manganese ore for enhanced lithium-ion battery performance

Implementing manganese-based electrode materials in lithium-ion batteries (LIBs) faces several challenges due to the low grade of manganese ore, which necessitates multiple purification and transformation steps before acquiring battery-grade electrode materials, increasing costs. At present, most Lithium Manganese Oxide (LMO) materials are synthesized using electrolytic manganese dioxide, and the development of new processes, such as hydrometallurgical processes is important for achieving a cost-effective synthesis of LMO materials. In this work, we develop a full synthesis process of LMO materials from manganese ore, through acid leaching, forming manganese sulfate monohydrate (MnSO4·H2O), an optimized thermal decomposition (at 900, 950 or 1000 °C) producing different Mn3O4 materials and a solid-state reaction, achieving the synthesis of LMO. The latter was used as a cathode material for LIB exhibiting a specific capacity comparable to the state-of-the-art LMO cathode with a remarkable cycling stability of 800 cycles with <20 % in capacity loss. These performances were attributed to the excellent redox reversibility of the LMO cathode, characterized by voltammetry and in operando and in situ characterization by Raman and XRD.

Machine learning-assisted DFT-prediction of pristine and endohedral doped (O and Se) Ge12C12 and Si12C12 nanostructures as anode materials for lithium-ion batteries

Nanostructured materials have gained significant attention as anode material in rechargeable lithium-ion batteries due to their large surface-to-volume ratio and efficient lithium-ion intercalation. Herein, we systematically investigated the electronic and electrochemical performance of pristine and endohedral doped (O and Se) Ge12C12 and Si12C12 nanocages as a prospective negative electrode for lithium-ion batteries using high-level density functional theory at the DFT/B3LYP-GD3(BJ)/6-311 + G(d, p)/GEN/LanL2DZ level of theory. Key findings from frontier molecular orbital (FMO) and density of states (DOS) revealed that endohedral doping of the studied nanocages with O and Se tremendously enhances their electrical conductivity. Furthermore, the pristine Si12C12 nanocage brilliantly exhibited the highest Vcell (1.49 V) and theoretical capacity (668.42 mAh g− 1) among the investigated nanocages and, hence, the most suitable negative electrode material for lithium-ion batteries. Moreover, we utilized four machine learning regression algorithms, namely, Linear, Lasso, Ridge, and ElasticNet regression, to predict the Vcell of the nanocages obtained from DFT simulation, achieving R2 scores close to 1 (R2 = 0.99) and lower RMSE values (RMSE < 0.05). Among the regression algorithms, Lasso regression demonstrated the best performance in predicting the Vcell of the nanocages, owing to its L1 regularization technique.

Recent Advancements of Graphene and Some Selected Graphene-Based Electrode Materials for Lithium-Ion Battery

Graphene is a two-dimensional monolayer of carbon atoms arranged in a hexagonal lattice consisting of sp2 hybridized conjugated carbon atoms and serves as a promising electrode material for lithium-ion batteries (LIBs) owing to its superior properties, including a high specific surface area (2630 m2g-1), a high theoretical capacity (744 mAhg-1), excellent electrical conductivity, and a wide electrochemical potential window. Despite having these superior properties, the restacking as well as the van der Waals forces of attraction among the graphene layers and the long path for Li-ion diffusion are factors that reduce the specific surface area and active site for Li-ion storage, which in turn influence the electrochemical performance of LIBs. The functionalization of graphene to porous graphene, graphene quantum dots, and graphene oxides, as well as the integration of graphene with other foreign materials such as transitional metal oxides, various heteroatoms (boron, nitrogen, sulfur, etc.), and covalent organic frameworks (COF), are the two main strategies that have been widely applied to improve the properties of graphene for Li-ion battery applications. In this review, recent works regarding the performance of graphene and graphenebased electrode materials for LIBs applications were reviewed and presented in detail. Moreover, various graphene fabrication techniques in terms of quality and quantity of graphene produced as well as the future overview of graphene and some selected graphene-based materials for LIBs applications have been assessed and summarized.

Structurally-constrained wrinkled NiO nanomembranes for high-performance lithium and sodium storage

In light of its exceptional capacity and safety features, nickel oxide (NiO) has emerged as a highly promising electrode material for advanced lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs), which operate through conversion mechanisms, meeting the growing demand for high-efficiency rechargeable batteries. To address the capacity degradation challenges associated with NiO anodes, we present an innovative approach involving the fabrication of wrinkled NiO nanomembranes through magnetron sputtering deposition followed by thermal treatment. This distinctive three-dimensional, ultra-thin architecture integrates nanostructural and microstructural features that effectively reduce ionic diffusion distances and mitigate dimensional fluctuations during cycling, thereby markedly enhancing the electrochemical performance and reliability. Specifically, for lithium storage, these wrinkled NiO nanomembranes achieve an impressive reversible specific capacity of 773 mA h g−1 at 100 mA g−1, with excellent rate capability of 468 mA h g−1 at 5000 mA g−1 and long-term cycling performance, maintaining 523 mA h g−1 at 500 mA g−1 even after 1000 cycles. Likewise, for sodium storage, they exhibit a substantial reversible capacity of 288 mA h g−1 at 50 mA g−1 and retain 202 mA h g−1 at 200 mA g−1 after 100 cycles. These findings underscore the promising application of wrinkled NiO nanomembranes as robust anodic materials for high-performance LIBs and SIBs.

Characterization of identical lithium-ion battery electrodes before and after charge/discharge cycles via in-plane large-area polishing

As an effective method to fabricate a large-area cross-sectional sample for lithium-ion battery electrodes, we perform in-plane polishing of LiNi0.8Co0.15Al0.05O2(NCA) cathode samples and obtain a large cross-sectional area with a diameter of 1.5 mm. The polished cross-sections of NCA cathode particles are sufficiently flat to perform the atomic force microscopy (AFM) measurements on each cathode particle. Following AFM-based Kelvin probe force microscopy and scanning spreading resistance microscopy measurements, an identical in-plane polished NCA sample is assembled into a coin cell for the charge and discharge processes. After 90 charge/discharge cycles, the in-plane-polished sample is successfully disassembled from the coin cell without causing critical damage. In addition, a microcrack structure, which is a typical degradation feature of the cycles of NCA particles, is observed for the identical in-plane polished NCA sample. This indicates that the in-plane polishing method is effective for investigating identical NCA electrode samples before and after the charge/discharge process. Furthermore, the in-plane polishing method can be successfully applied to the large-area polishing of a Si-based anode which is a mixture of Si carbon complexes and graphite particles. This study presents a novel methodology for analyzing the degradation of lithium-ion battery electrode materials.

Recycling Electrode Materials of Spent Lithium-Ion Batteries for High-Efficiency Catalyst Application: Recent Advances and Perspectives

Recycling Electrode Materials of Spent Lithium-Ion Batteries for High-Efficiency Catalyst Application: Recent Advances and Perspectives

Iron-based bimetallic oxide carbon composites with superior lithium storage capabilities serve as anode in lithium-ion batteries

Transition metal oxides (TMOs) have emerged as highly promising electrode materials for lithium-ion batteries (LIBs) owing to their versatile valence states and distinctive morphological attributes. Bimetallic oxides, in particular, exhibit the ability to mitigate the volume expansion associated with lithium alloying and de-alloying processes. Despite these advantages, metal oxides often suffer from drawbacks such as poor conductivity, limited cycle stability, and a propensity for lithiation. Addressing the challenges of low electronic conductivity, significant volume expansion, and inadequate uniformity, we synthesized two bimetallic oxide-based carbon composites via a “one-pot” solvothermal approach: ZnFe2O4@C and MnFe2O4@C. These composites are enveloped in a carbon shell derived from anhydrous ethanol. Notably, the specific discharge capacities of ZnFe2O4@C and MnFe2O4@C surpass those of their respective single metal oxide counterparts. Following nearly 300 cycles of charge and discharge operations at a current density of 100 mA g−1, ZnFe2O4@C exhibited a specific discharge capacity of 1528 mAh g−1, while MnFe2O4@C demonstrated a capacity of 1283 mAh g−1. The synthesis method offers simplicity, high yield, and uniform morphology, making it a promising avenue for enhancing the performance of LIBs electrode materials.

Core-shell structure and high rate performance of Ce-doped Li4Ti5O12 for lithium-ion battery anode materials

Lithium titanate (LTO) can be a very promising anode material for lithium-ion batteries (LSBs) due to its inherent ability to inhibit the growth of lithium dendrites as well as its unique “zero-strain” properties. Unfortunately, the low electronic conductivity of LTO leads to serious shortcomings in higher electrochemical demands. In this work, the Ce3+-doped C@Li4Ti5-xCexO12 (x = 0, 0.1, 0.15 and 0.2) anode materials synthesized by the hydrothermal method using carbon spheres as templates showed more significant improvement in both structural and electrochemical properties. The results demonstrate that electronic conductivity, lithium-ion diffusion rate, discharge specific capacity, discharge rate capability, and significant improvement stability of C@Li4Ti5-xCexO12 (x = 0.1, 0.15 and 0.2) electrodes. Among them, C@Li4Ti4.85Ce0.15O12 electrode exhibits the highest initial discharge specific capacity (250.86 mAh/g) at 0.1C, which is 1.28-fold that of C@ Li4Ti5O12 (195.94 mAh/g), and initial discharge capacity from 205.96 mAh/g to 170.39 mAh/g after 500 cycles, corresponding to 82.7 % of the initial stable discharge capacity. The outstanding performance of C@Li4Ti4.85Ce0.15O12 can be attributed to the lower interfacial impedance, higher electronic conductivity, high oxygen vacancy concentration, and moderate amount of Ce3+ doping can enhance the electrochemical activity. In addition, carbon sphere surface defects shown to be effective in improving lithium-ion storage. This work demonstrates that Ce3+ doping is an effective method to improve the electrochemical performance of LTOs and provides a more effective guide for designing and optimizing anode electrode materials for lithium-ion batteries

Cobalt-free spinel–layered structurally integrated Li0.8Mn0.64Ni0.183Fe0.091O2 cathodes for lithium-ion batteries

Cobalt-free, Li-rich layered-spinel structurally integrated positive electrode (cathode) materials for lithium-ion batteries (LIBs), with nominal composition 0.6(Li1.2Mn0.56Fe0.08Ni0.16O2) 0.4(LiFe0.2Mn1.4Ni0.4O4) which can otherwise be written as Li0.8Mn0.64Ni0.183Fe0.091O2 (FeSL) are synthesized via simple citric acid-assisted sol-gel route. Four different final annealing temperatures (550 °C, 650 °C, 750 °C, and 850 °C) were chosen to investigate their influence on electrochemical performance. The obtained composite materials contain spinel (space group Fd3¯m) as well as Li-rich layered phases (space group C2/m) as revealed by X-ray diffraction (XRD), HRTEM and cyclic voltammetry investigations. The excellent electrochemical performance of the composite material could be attributed to the structural stability achieved by the integration of spinel and layered components. Selected synthesized composite materials exhibit high discharge capacities close to 200 mAh g−1. The FeSL750 shows better capacity retention (92(3)% at the 50th cycle and 82(5)% at the 70th cycle) and rate capability than the FeSL550 and FeSL650 samples. However, the FeSL850 sample shows different charge-discharge behaviour. The charge capacity corresponding to FeSL850 is found to increase up to the 20th cycle, then stabilizes and displays a capacity retention of almost 100 % at the 50th cycle and 91(1)% at the 70th cycle. The electrochemical mechanism of FeSL750 was elucidated via in operando XAS investigations, which reveal electrochemical activity from all transition metals.

In situ anchoring of FeNi nanoparticles into three-dimensional nitrogen-doped carbon framework as a self-supporting electrode for high-performance lithium storage

Constructing free-standing electrodes with superior lithium storage capacity and good mechanical performance are fascinating for next-generation lithium-ion batteries (LIBs). Nevertheless, their practical application is hindered by complicated synthesis procedures and high cost. Herein, a highly stable, self-supporting and flexible electrode material for LIBs was constructed by encapsulating spherical FeNi nanoparticles into one-dimensional N-doped carbon fiber film (FeNi/N- CFM) using the electrospinning technique and subsequent heat treatment. The FeNi/N-CFM can be directly used as anode materials for LIBs without conductive additive, current collector and binder. The synergistic effect of uniformly dispersed small FeNi nanoparticles and three-dimensional (3D) conductive network constructed by CF framework effectively improves the utilization rate of active materials, enhances the transport of both electrons and lithium ions, facilitates the electrolyte penetration, and promotes the lithium-ion storage kinetics and stability, thus leading to a greatly enhanced electrochemical performance. Benefiting from the unique architectural feature and flexibility, the FeNi/N-CFM composites employed as binder-free electrodes for LIBs exhibit good lithium storage performance (an initial discharge capacity of 1031.5 mA h g−1 and a reversible capacity of 481.3 mA h g−1 at 100 mA g−1 after 100 cycles), rate capacity (305.1 mA h g−1 at 1000 mA g−1) and outstanding reversibility (coulombic efficiency of around 100 % after 100 cycles). Furthermore, this work also provides a facile and effective pathway to design and fabricate free-standing electrodes.

High-Performance Polyimide Covalent Organic Frameworks for Lithium-Ion Batteries: Exceptional Stability and Capacity Retention at High Current Densities.

Organic polymers are considered promising candidates for next-generation green electrode materials in lithium-ion batteries (LIBs). However, achieving long cycling stability and capacity retention at high current densities remains a significant challenge due to weak structural stability and low conductivity. In this study, we report the synthesis of two novel polyimide covalent organic frameworks (PI-COFs), COF-JLU85 and COF-JLU86, by combining truxenone-based triamine and linear acid anhydride through polymerization. These PI-COFs feature layers with pore channels embedded with 18 carbonyl groups, facilitating rapid lithium-ion diffusion and enhancing structural stability under high current densities. Compared to previously reported organic polymer materials, COF-JLU86 demonstrates the excellent performance at high current densities, with an impressive specific capacity of 1161.1 mA h g-1 at 0.1 A g-1, and outstanding cycling stability, retaining 1289.8 mA h g at 2 A g-1 after 1500 cycles and 401.1 mA h g-1 at 15 A g-1 after 10000 cycles. Additionally, in-situ infrared spectroscopy and density functional theory (DFT) calculations provide mechanistic insights, revealing that the high concentration of carbonyl redox-active sites and the optimized electronic structure contribute to the excellent electrochemical performance.

Exploring the Electrochemical Superiority of V2O5/TiO2@Ti3C2-MXene Hybrid Nanostructures for Enhanced Lithium-Ion Battery Performance.

The use of vanadium(V)-based materials as electrode materials in electrochemical energy storage (EES) devices is promising due to their structural and chemical variety, abundance, and low cost. V-based materials with a layered structure and high multielectron transfer in the redox reaction have been actively explored for energy storage. Our current work presents the structural and electrochemical properties of a vanadium-based composite with TiO2@Ti3C2 MXene, referred to as VM. This composite is obtained through the in situ thermal decomposition of the VO2(OH)/Ti3C2mixture, which is achieved by solution mixing and drying. The material structure is confirmed using various characterization tools, which establish an orthorhombic V2O5 nanostructure compositing with nanocrystalline TiO2@Ti3C2. VM with 5 wt % MXene, referred to as VM5, can achieve 460 mAhg-1 at a current density of 0.1 Ag1- and 290 mAhg-1 at 1 Ag1-, with an average coulombic efficiency of 98.5%. The presence of the V2O5/TiO2 (nanocrystals) heterojunction attached with Ti3C2 sheets contributed to reduced charge transfer resistance. The cyclic stability shows a capacity retention of 62% over 500 cycles at 1 Ag1- (4C rate, where 1C equals 0.25 Ag1-) with a 0.22 capacity drop with each cycle. Dunn's approach to examining the charge storage mechanism demonstrates 72% contribution of the surface-dominant capacitive process and 28% of the diffusion-controlled intercalation process at 0.4 mVs-1, suggesting a potential high-performance pseudocapacitive hybrid electrode material for lithium-ion batteries.

Impact of Mn/Ni and Li/(Mn+Ni) ratios on phase equilibrium and electrochemical performance of the high voltage spinel LiNi0.5Mn1.5O4

LiNi0.5Mn1.5O4 (LNMO) emerges as a promising spinel-type positive electrode material for lithium-ion batteries (LIBs) due to its low cost and high operating voltage (4.8 V vs. Li+/Li), attributed to the Ni4+/Ni3+/Ni2+ redox couples, which contribute to high energy density, a crucial requirement for next-generation LIBs. In this study, we investigate the influence of Mn/Ni and Li/(Mn + Ni) ratios on the phase equilibrium and electrochemical performance of LNMO positive electrode materials. A series of 18 samples were synthesized using a two-stage solid-state method with varying Mn/Ni and Li/(Mn + Ni) ratios and annealing under different atmospheres. These synthesis conditions have major impact on the composition and level of purity of LNMO phases, as well as on the nature of the impurities themselves. Mn excess significantly enhances the electrochemical performance, with superior discharge capacity, coulombic efficiency, and capacity retention for the Mn-rich sample with Li/(Mn + Ni) = 0.50. A comprehensive structural analysis combining synchrotron X-ray and neutron powder diffraction gives an in-depth characterization of these samples with a clear differentiation between the global Mn content within samples and that within the LNMO phase.

Novel metal-organic anode material by in-situ chelating Ni2+ with tannic acid on carbon nanotube for high-performance Li storage

Lithium-ion batteries (LIBs) with natural organic anode are attracting intensive interest for application owing to their structural diversity, cost-effectiveness, eco-friendliness, and high specific capacity. However, directly usage of natural organic materials as anode materials usually encounters poor electrochemical properties such as low reversible capacity and short cycling life. Thus, developing high-performance organic electrode materials for LIBs remains a great challenge. Herein, we present a rational design and fabrication of TA-Ni@CNTs by in-situ coating TA-Ni polymers onto the surface of carbon nanotubes (CNTs) as a superior anode material for LIBs. Specifically, the highly conductive CNTs can effectively relieve the aggregation of TA-Ni and improve the electronic conductivity. Meanwhile, the strong chelation among nickel irons and catechol groups enhances the structure stability and inhibits the dissolving property. Consequently, as an anode material for LIBs, the resulting TA-Ni@CNTs achieves a high reversible capacity of 1418.8 mAh·g−1 at 0.1 A·g−1 after 216 cycles and an outstanding cycling stability with 951.1 mAh·g−1 at 0.5 A·g−1 after 323 cycles. The presented design strategy holds great promise for developing more-efficient electrode materials for LIBs.

Metal-Organic Frameworks as Electrode Materials for Lithium-Ion Battery

Over recent decades, Metal-Organic Frameworks (MOFs) have distinguished themselves as a unique class of porous materials due to their adaptable surface and structural properties. This versatility has made MOFs highly relevant across various fields, including drug delivery, gas separation, catalysis, and sensor technology. Additionally, their conductive properties have made them promising candidates for use in energy storage systems like high-energy-density batteries and supercapacitors. MOFs are particularly noted for their role in the development of rechargeable lithium-ion batteries (LIBs) and supercapacitors, where they serve as both anode and cathode materials. The ability to fine-tune MOFs at a molecular level allows for precise control over their structure and chemistry, enhancing their functionality in energy storage applications. This control facilitates superior electronic and ionic transport within MOFs, which is critical during the charging and discharging cycles of LIBs. This review delves into the various synthetic methods used to develop specific MOF structures, focusing on their implementation within LIBs to improve cyclic stability and discharge capacity. Recent advancements in MOF technology as anode and cathode materials are explored, providing insights into how these developments can optimize reaction conditions and design choices within the battery development community and broader electrochemical energy storage sectors. The aim is to highlight how MOFs’ inherent characteristics can be leveraged to enhance the performance and efficiency of energy storage devices.

Surface engineering of TiSiO4 nano-coating for high-voltage nickel-rich ternary cathodes: An approach to improve cyclic performance

In recent years, layered ternary transition metal oxides with a high nickel content have gained substantial attention as a potential positive electrode material for lithium-ion batteries. However, its poor rate capability, cyclability, and capacity retention at high working voltages limit its use in commercial lithium-ion batteries. To overcome these challenges, we synthesize a cost-effective wet-chemical deposition of novel TiSiO4 nano-coatings over the surface of LiNi0.83Mn0.06Co0.11O2 (NMC-83). X-ray diffraction and electron microscopy confirm the presence of a coating and verify that the deposition process did not alter the crystallinity and morphology of the NMC-83 particles. In addition, during cycling, it completely protects NMC-83 with enhancements in hexagonal phase transitions between H2 and H3, resulting in excellent cycling stability at upper cut-off voltages. Likewise, when the amount of coated material is equal to 1 wt%, it provides faster ion kinetics and a stable electrode-electrolyte interface. The 1 wt% TiSiO4 coating provides 35 % retention after 250 cycles at a 0.5C rate, while the pristine NMC-83 shows only 13.7 %. From postmortem analysis, the 1 wt% TiSiO4-coated NMC-83 cathode maintains its stable polycrystalline nature compared with pristine NMC-83. Thus, this novel TiSiO4 nanocoating has significant implications for developing high-performance rechargeable batteries for energy applications.

High-Performance p-type organic electrode materials with oxygen atoms as active centers enabled by molecular design and in situ electropolymerization

Redox-active organic molecules are considered to be one type of promising electrode materials for next generation lithium-ion batteries (LIBs), among which p-type electrode materials with higher voltage and outstanding reaction kinetics receive much attention. However, it is a great challenge to develop p-type materials with oxygen atom as the active center and the electrochemical performance of the few reported examples needs significant improvement. Herein, 1,3,5-tri(benzofuran-2-yl)benzene (TBFB) was elaborately designed and facilely synthesized through one-step Suzuki coupling reaction from commercially available raw reagents. When used as p-type electrode material for LIBs, it was found that TBFB with poor solubility can be effectively in situ electropolymerized during the charging process, forming more insoluble polymers. Experimental results demonstrate that TBFB electrode achieves a high specific capacity of 179.1 mAh g−1 and an ultralong cycle life of 8000 cycles. This work manifests the electrochemical performance of p-type organic electrode materials with oxygen atom as active center can be effectively enhanced by rational molecular design and in situ electropolymerization method.

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.