Anode Material For Li-ion Batteries Research Articles

From waste graphite fines to revalorized anode material for Li-ion batteries

A crucial step in the production of battery grade natural graphite for lithium-ion batteries is the spheroidization process. However, the spheroidization yield is typically only about 50%. The by-product consists of graphite fines that are not suitable for use in lithium-ion batteries due to their small particle size (<10 μm), therefore, graphite fines are discarded or sold at a loss. In this work, we report a method for graphite fines re-agglomeration and petroleum pitch coating that allows for revalorization and recycling of waste graphite from the spheroidization process. Re-agglomeration of graphite fines was achieved by spray drying technique using carboxymethyl cellulose as binder and citric acid as cross-linking agent to improve the mechanical strength of the agglomerate. The as-obtained particles were subjected to heat treatment in presence of petroleum pitch for simultaneous binder and pitch decomposition to obtain pitch-coated particles. Resulting agglomerate particles showed a median size comparable to a commercial battery grade natural graphite reference and proved structurally sound to withstand the electrode calendering process. Pitch-coated agglomerate particles exhibited lower surface area and improved stability in comparison with non-coated graphite agglomerate. The electrochemical performance of the coated material was comparable to a commercial graphite reference, particularly in terms of cumulative irreversible capacity. Analysis by X-ray nano-computed tomography provided further insight into morphological properties and dimensional changes after calendering and upon galvanostatic cycling. Overall, the material obtained through this method shows great potential for re-introduction in the production chain of battery grade natural graphite for lithium-ion batteries.

Facile preparation of Fe3O4/ZnFe2O4/ZnS/C composite from the leaching liquor of jarosite residue as a high-performance anode material for Li-ion batteries

A Fe3O4/ZnFe2O4/ZnS/C composite is synthesized through a facile thermal decomposition method under an oxygen insufficient condition with the leaching liquor of ammonium jarosite residue and sucrose as raw materials. It reveals that the sucrose dosage (with nFe:nsucrose of 1:0, 1:1, 1:2, and 1:3, respectively) has a crucial impact on the microstructure, composition, and lithium storage property of the prepared samples. Particularly, the sample prepared with the nFe:nsucrose of 1:2 (labeled as FZ-2) has a porous structure in which nanosized Fe3O4, ZnFe2O4, and ZnS are embedded in the carbon matrix. Due to the porous morphology and synergistic effects of different components in the sample, this Fe3O4/ZnFe2O4/ZnS/C composite exhibits high lithium storage activity, superior cycling stability (928 mAh g−1 after 300 cycles at 500 mA g−1), and excellent high-rate capability (371 mAh g−1 at 5000 mA g−1). Lithium storage kinetics analysis demonstrates that the Fe3O4/ZnFe2O4/ZnS/C has much lower electrochemical reaction resistance, smaller polarization, faster Li+ diffusivity, and more remarkable pseudocapacitive behavior than the Fe2O3/ZnFe2O4 counterpart. This work realizes the low-cost and facile fabrication of high-valued anode material for LIBs and the comprehensive utilization of Fe, Zn, and S resource in jarosite residue, achieving the interdisciplinary between resource recovery and electrochemical energy storage.

Highly conductive and robust telluride-carbon hybrid matrix for enhanced copper diphosphide anode in Li-ion batteries

CuP2 is a phosphorous-rich transition metal phosphide that can be a potential anode for Li-ion batteries (LIBs) because of its high theoretical capacity (∼1280 mA h g−1) and intrinsic alleviation of volume change owing to the presence of inactive Cu. Despite these advantages, the electrochemical performance of CuP2 is not satisfactory owing to its low electrical conductivity and insufficient regulation of large volume expansion during cycling. Herein, we propose a CuP2-Te-C ternary composite as a high-performance anode material for LIBs. The presence of Te-C can circumvent the limitations of CuP2, as it can synergistically increase the electrical conductivity while mitigating the cycling instability. The individual roles of Te and C in enhancing the active CuP2 performance were studied using various morphological and electrochemical characterizations. Furthermore, an appropriate C content (25 wt%) that can increase the specific capacity while maintaining cycling stability was determined. Under these conditions, CuP2-Te-C(25 %) displayed a good cycling performance (532 mA h g−1 at 100 mA g−1 after 100 cycles) and rate capability (501 mA h g−1 at 3.0 A g−1). The superior performance of CuP2-Te-C(25 %) studied comprehensively using electrochemical impedance spectroscopy revealed a higher diffusivity and lower charge transfer resistance for CuP2-Te-C(25 %) than its counterparts. This study presents new perspectives on high-performance metal-phosphide anode materials for LIBs.

Synthesis of porous C/Fe3O4 microspheres by spray pyrolysis with NaNO3 additive for lithium-ion battery applications

In this work, we successfully synthesized porous C/Fe3O4 microspheres by spray pyrolysis at 700ºC with a sodium nitrate (NaNO3) additive in the precursor solution. Furthermore, we studied their electrochemical properties as anode material for Li-ion batteries. The systematic studies by various characterization techniques show that NaNO3 catalyzes the carbonization of sucrose and enhances the crystallization of Fe3O4. Moreover, an aqueous etching can easily remove sodium compounds to produce porous C/Fe3O4 microspheres with large surface areas and pore volumes. The porous C/Fe3O4 microspheres exhibit a reversible capacity of ~780 mAh g–1 in the initial cycles and ~520 mAh g–1 after 30 cycles at a current density of 50 mA g–1. Moreover, a reversible capacity of ~400 mAh g–1 is attainable after 200 cycles, even at a high current density of 500 mA g–1. The wide range of pores produced from the removal of sodium compounds might enable easy electrolyte penetration and facilitate fast Li-ion diffusion, while the N-doping can promote the electronic conductivity of the carbon. These features of porous C/Fe3O4 microspheres led to the improved electrochemical properties of this sample.Graphical

Effect of electrolytes on the performance of graphene oxide anode material for ultracapacitor, Li-ion capacitor, and Li-ion battery: three-in-one approach

Graphene-based 2D nanomaterials are gaining much interest in energy storage systems, specifically in ultracapacitors. Various electrolytes increase the performance of ultracapacitor (UC), Li-Ion capacitor (LIC), and Li-Ion battery (LIB). In the present work, we have successfully designed a "three-in-one" artificial method to engineer anode from a single precursor for high-performance UC, LIC, and LIB. In the present investigation, graphene oxide (GO) slurry was developed using the modified Hummers’ method. The effect of KOH, H2SO4, and KCl electrolytes on electrochemical performance of UC was demonstrated. The LiPF6 organic electrolyte solution on electrochemical performance of LIC and LIB is demonstrated. The GO deposited on stainless steel electrode achieved its highest specific capacitance of 422 F/g, energy density of 45.50 kWh/kg, and power density of 10,000 W/kg in 3.0 M in KCl, whereas GO as an anode material delivered a first discharge capacity of 456 mAh/g at 0.05 A/g current density with the efficiency of 100%.

Enhanced Energy Storage Performance of Zr-Doped TiNb2O7 Nanospheres Prepared by the Hydrolytic Method

The use of TiNb2O7 (TNO) as an anode material for Li-ion battery is attracting tremendous attention because of its stable structure and high theoretical capacity. However, the inherent poor electronic conductivity and ionic conductivity restrict its practical application. Herein, we designed and prepared zirconium-doped TiNb2O7 nanospheres (Zrx-TNO NSs, x = 0, 0.05, 0.010) with pores through a simple hydrolysis method to adjust the lattice spacing and electron distribution. The nanosphere-structured electron materials with pores can not only prevent aggregation of active materials but also provide more channels for Li+ and electrons’ transportation. Meanwhile, X-ray diffraction coupled with high-resolution transmission electron microscopy results verified the crystal spacing increasement. The X-ray photoelectron spectrum exhibited partial reduction of metal atoms. As a result, Zr0.05-TNO NSs showed improved cycling stability in the half cell (i.e., delivers a reversible capacity of 170 mA h/g at 5 C after 1000 cycles). It also showed excellent performance in the rate capabilities of 260.0 and 177.8 mA h/g at 0.5 and 10 C, making it highly competitive for quick-charging lithium-ion batteries.

Sonoelectrochemical Nanoarchitectonics of Crystalline Mesoporous Magnetite @ Manganese Oxide Nanocomposite as an Alternate Anode Material for Energy-Storage Applications

In this report, the synergetic sonoelectrochemical method was utilized to produce magnetite nanoparticles was doped with MnO2 with the assistance of ultrasound to form nanoarchitectonic magnetic crystals with a mesoporous magnetite @ manganese dioxide (m-Fe3O4@MnO2) hybrid nanostructure. The hybrid nanocomposite was rapidly produced based on the nucleation and growth of pure iron-oxide nanocrystals in the electrochemical system. The nanocomposite was pure, highly amorphous, and mesoporous in nature; the magnetite was spherical in shape, with an average diameter of 45 ± 10 nm and a MnO2-plane length of 420 ± 30 nm. The stability of the pure m-Fe3O4 was enhanced from 89.61 to 94.04% with negligible weight loss after adding manganese dioxide and the stable formation of the hybrid nanostructure. Based on the superior results of the material, it was utilized as an anode material in Li-ion batteries. The m-Fe3O4@MnO2 hybrid nanostructure had a highly active surface area, which enhanced the interfacial interaction between the Li-ion and the metal surface; it delivered 1513 mAh g−1 and 1290 mAh g−1 as the first specific discharge and charge capacity, respectively, with 85% coulombic efficiency, and it showed an excellent cyclic reversibility of 660 mAh g−1 with a coulombic efficiency of almost 99% at current density of 1.0 A g−1.

TiO2-Coated Silicon Nanoparticle Core-Shell Structure for High-Capacity Lithium-Ion Battery Anode Materials

Silicon-based anode materials are considered one of the highly promising anode materials due to their high theoretical energy density; however, problems such as volume effects and solid electrolyte interface film (SEI) instability limit the practical applications. Herein, silicon nanoparticles (SiNPs) are used as the nucleus and anatase titanium dioxide (TiO2) is used as the buffer layer to form a core-shell structure to adapt to the volume change of the silicon-based material and improve the overall interfacial stability of the electrode. In addition, silver nanowires (AgNWs) doping makes it possible to form a conductive network structure to improve the conductivity of the material. We used the core-shell structure SiNPs@TiO2/AgNWs composite as an anode material for high-efficiency Li-ion batteries. Compared with the pure SiNPs electrode, the SiNPs@TiO2/AgNWs electrode exhibits excellent electrochemical performance with a first discharge specific capacity of 3524.2 mAh·g-1 at a current density of 400 mA·g-1, which provides a new idea for the preparation of silicon-based anode materials for high-performance lithium-ion batteries.

A new strategy for preparation of copper oxides composites as anode materials for Li-ion storage

Low-cost copper oxides that can be employed as anode materials for Li-ion batteries have attracted much attention in recent years. However, the unsatisfactory electrochemical properties are hindering the application of copper oxides. In this study, a new strategy has been proposed for the preparation of copper oxide composites. An imine-linked metal-organic framework material FDM-71 was employed to prepare Cu/Cu2O/C composite. The composite coated with ultrathin carbon layer exhibits excellent electrochemical properties compared with the reported results. Due to the remarkable rate-capability, long cycling life and high specific discharge capacity, the Cu/Cu2O/C composite can be considered as a promising anode material for Li-storage.

Tuning original anion defects for Co3O4 to promote heteroatom doping with different valences for enhanced lithium storage

Reasonable design of the composition and concentration of point defects is of great significance for optimizing electrode materials. In this paper, a vacancy-assisted doping strategy has been proposed to modulate Co3O4 defects (oxygen vacancies and heteroatoms doping) to improve its electronic and electrochemical performance as an anode material for Li-ion batteries. Through environmentally friendly and efficient plasma treatment, the content of oxygen vacancies (OVs) in Co3O4 can be easily modulated, and the higher the concentration of OVs, the better conducive to subsequent heteroatom doping (P, S) via thermal treatment at low temperature. Moreover, the optimized OVs-assisted P-doped Co3O4 shows the best electrochemical performance due to the improved ion diffusion kinetics, electron conductivity, the structure stability and the improved adsorption energy of lithium ions, which are verified by the experimental results and DFT calculations.

Operando study of mechanical integrity of high-volume expansion Li-ion battery anode materials coated by Al2O3

Group IV elements and their oxides, such as Si, Ge, Sn and SiO have much higher theoretical capacity than commercial graphite anode. However, these materials undergo large volume change during cycling, resulting in severe structural degradation and capacity fading. Al2O3 coating is considered an approach to improve the mechanical stability of high-capacity anode materials. To understand the effect of Al2O3 coating directly, we monitored the morphology change of coated/uncoated Sn particles during cycling using operando focused ion beam–scanning electron microscopy. The results indicate that the Al2O3 coating provides local protection and reduces crack formation at the early stage of volume expansion. The 3 nm Al2O3 coating layer provides better protection than the 10 and 30 nm coating layer. Nevertheless, the Al2O3 coating is unable to prevent the pulverization at the later stage of cycling because of large volume expansion.

Toward the Improvement of Silicon-Based Composite Electrodes via an In-Situ Si@C-Graphene Composite Synthesis for Li-Ion Battery Applications

Using Si as anode materials for Li-ion batteries remain challenging due to its morphological evolution and SEI modification upon cycling. The present work aims at developing a composite consisting of carbon-coated Si nanoparticles (Si@C NPs) intimately embedded in a three-dimensional (3D) graphene hydrogel (GHG) architecture to stabilize Si inside LiB electrodes. Instead of simply mixing both components, the novelty of the synthesis procedure lies in the in situ hydrothermal process, which was shown to successfully yield graphene oxide reduction, 3D graphene assembly production, and homogeneous distribution of Si@C NPs in the GHG matrix. Electrochemical characterizations in half-cells, on electrodes not containing additional conductive additive, revealed the importance of the protective C shell to achieve high specific capacity (up to 2200 mAh.g-1), along with good stability (200 cycles with an average Ceff > 99%). These performances are far superior to that of electrodes made with non-C-coated Si NPs or prepared by mixing both components. These observations highlight the synergetic effects of C shell on Si NPs, and of the single-step in situ preparation that enables the yield of a Si@C-GHG hybrid composite with physicochemical, structural, and morphological properties promoting sample conductivity and Li-ion diffusion pathways.

Facile fabrication of Li5Cr7Ti6O25@Li0.33La0.56TiO3 composites as promising anode materials for high-performance Li-ion batteries

Li5Cr7Ti6O25 has been considerd as a hopeful anode material of Li-ion batteries due to the low cost. Nonetheless, the intrinsically low conductivity obviously reduces reversible capacity and cycle performance. In this work, we design Li5Cr7Ti6O25@Li0.33La0.56TiO3 (LCTO@LLTO) composites by simple ball-milling process followed by a post-calcination at air atmosphere, which realizes an excellent cycle performance. The Li0.33La0.56TiO3 (LLTO) coating does not alter the morphology and particle size of the Li5Cr7Ti6O25 (LCTO) material, but increses the lattice parameter. The right level LLTO modification can improve the transfer ability of ions and electrons with enhanced lithiation/delithiation dynamics, making a good cycling stability and rate capability of as-prepared LCTO anode. As a result, LCTO@LLTO(5 wt%) shows a high charge capacity of 149.8 mAh g−1 even at 1C in the 50th cycle, much higher than that LCTO with a capacity of 126.3 mAh g−1. The improved electrochemical performance of LCTO@LLTO composites can be attribute to the enhanced Li ion diffusion kinetics, electrochemical reversibility and ion conductivity by LLTO modification. Therefore, the LLTO modificationcan be regarded as an efficient way for construct the anode materials for high-perfprmance Li-ion batteries.

Identification of Borophosphene/graphene heterostructure as anode for Li-ion Batteries and its origin

The development of two-dimensional (2D) material or heterostructure as an anode material is necessary to enhance the electrochemical performance of Li-ion batteries (LIBs) but finding the correct combination is a challenge. In the present work, using First principles study, we have proposed borophosphene (BP-ML) and graphene-based multilayer heterostructure as a possible anode material. We have found that BP-ML and graphene-based heterostructure are conductive in nature. Here, we have also investigated the role of Pz (π) and Py (σ) atomic orbital bands of BP-ML and graphene. On Li intercalation, charge transfer is mainly site and interface definitely which helps to improve the specific capacity. The specific capacity of the proposed heterostructure varies from 546 to 427 mA h/g. For maximum Li confirmation, the volume expansion of these heterostructures is about 14–16%. The presence of graphene helps to maintain the open-circuit voltage (OCV) of heterostructure on an average 0.7 V. Also, helps to support the diffusion barrier energy in the range of 0.27–0.71 eV. This proposed 2D heterostructure could be the future material for the LIB's anode material.

Synthesis and Electrochemical Properties of Co3O4@Reduced Graphene Oxides Derived from MOF as Anodes for Lithium-Ion Battery Applications

In this study, we utilized nano-sized Co3O4 and reduced graphene oxides (rGOs) as composite anode materials for Li-ion batteries. The Co3O4/C composite anode was derived from ZIF67 (Zeolitic Imidazolate Framework-67) and was wrapped in rGOs through precipitation. X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were used to identify the crystal structure, phase purity, and surface morphology of the composite. The composition-optimized Co3O4/rGO/C composite anode exhibited a reversible capacity of 1326 mAh/g in the first cycle, which was higher than that of the Co3O4/C composite anode with a capacity of 900 mAh/g at a current density of 200 mA/g. Moreover, after 80 cycles, Co3O4/rGO/C maintained a capacity of 1251 mAh/g at the same current density, which was also higher than the bare Co3O4/C composite (595 mAh/g). Additionally, the Co3O4/rGO/C composite exhibited a good capacity retention of 98% after 90 cycles, indicating its excellent cycling stability and high capacity. Therefore, the Co3O4/rGO/C electrode has great potential as a promising anode material for Li-ion batteries.

Theoretical investigations of Ti4C3 and Ti4C3T2 (T = F, O and OH) monolayers as anode materials for Li-ion batteries

Two-dimensional transition metals carbides have gained widespread researching attention as promising alternative anodes for rechargeable batteries due to their high reversible capacity. Herein, we study the electrochemical properties of Ti4C3 monolayer and its functionalized derivatives (Ti4C3T2) in Li-ion batteries by first-principles methods. The Ti4C3 and Ti4C3O2 monolayers show large capacities, able to adsorb two layers of Li on both sides of the monolayer, generating theoretical capacities of 470 and 412 mA·h/g, respectively. The diffusion barriers on bare Ti4C3 monolayer are 19.5 meV, which is lower than most of the 2D materials that have been reported. Finally, we also investigated the impact of intrinsic defects on adsorption and diffusion of Li on Ti4C3 and Ti4C3T2 monolayers. Calculations show that the introduction of carbon vacancies (VC) hinders Li adsorption on Ti4C3 and Ti4C3O2 monolayers but promotes Li adsorption on Ti4C3F2 monolayer. Titanium vacancies (VTi) facilitate the adsorption of Li on the Ti4C3F2 and Ti4C3O2 monolayers. The presence of vacancies also changes the diffusion behavior of Li. This work has a theoretical significance for the design of lithium-ion battery anode materials.

Construction of porous biphasic ZnTiO3 rods as anode materials for high-performance Li-ion batteries driven by a hybrid Li storage mechanism

Titanium-based oxide materials have become a potential candidate anode material for power LIBs due to its good structural stability and high safety performance. However, poor conductivity of titanium-based anode materials hinders their practical application. To solve this issue, porous ZnTiO3 rods and ZnTiO3/polytopamine (PDA) composites with excellent electrochemical properties were synthesized by solvothermal method and simple chemical polymerization in this work. The diameter of ZnTiO3 and ZnTiO3/PDA rods is around 800 nm. The ex-situ XRD and electrochemical characterization confirm that ZnTiO3 has intercalation, conversion and alloying reaction mechanism, resulting in higher capacity than most titanium-based anode materials. The ZnTiO3/PDA (6.2 wt%) anode possesses excellent cycling stability, which can provide a specific charge capacity of 467.1 mAh·g−1 after 500 cycles at 1000 mA·g−1. Moreover, after cycling, most of the ZnTiO3/PDA (6.2 wt%) still maintained the morphology of complete porous rods, indicating moderate PDA coating can significantly mitigate the volume change during the electrochemical reaction process and improve electrochemical properties. The EIS results demonstrate PDA coating can enhance the electrochemical reaction activity of ZnTiO3 materials. Therefore, the PDA coating is an effective approach to enhance the electrochemical performance of titanium-based anode materials.

Synthesis of olivine NaMnPO4 single crystals and electrochemical performance as anode material for Li-ion batteries

The direct synthesis of metastable olivine phase NaMnPO4 still remains a challenge. In this study, single crystals of the olivine NaMnPO4 were synthesized for the first time by a facile hydrothermal reaction. Single-crystal X-ray diffraction analysis provides precise structure information on the olivine structure of NaMnPO4. Moreover, the olivine NaMnPO4 can be completely transformed to its maricite phase after heating at 600 ​°C under Ar atmosphere, confirming the metastable nature of the olivine phase. Electrochemical performance of the olivine NaMnPO4 as anode material for Li-ion batteries (LIBs) was characterized. It delivers a capacity of 645.0 mAh g−1 ​at 0.1 ​A ​g−1 after 200 cycles. In contrast, the maricite phase NaMnPO4 exhibits very low lithium storage capacity.

Energy Storage Mechanism of C12-3-3 with High-Capacity and High-Rate Performance for Li/Mg Batteries.

The low specific capacity and Mg non-affinity of graphite limit the energy density of ion rechargeable batteries. Here, we first identify that the monolayer C12-3-3 in sp2-sp3 carbon hybridization with high Li/Mg affinity is an appropriate anode material for Li-ion batteries and Mg-ion batteries via the first-principles simulations. The monolayer C12-3-3 can achieve high specific capacities of 1181 mAh/g for Li and 739 mAh/g for Mg, higher than those of most previous anodes. The Li storage reaction is an "adsorption-conversion-intercalation mechanism", while the Mg storage reaction is an "adsorption mechanism". The 2D carbon material of C12-3-3 displays fast diffusion kinetics with low diffusion barriers of 0.41 eV for Li and 0.21 eV for Mg. As a new carbon-based anode material, the monolayer C12-3-3 will promote the practical application of batteries with high-capacity and high-rate performance.

The intrinsic electrostatic dielectric behaviour of graphite anodes in Li-ion batteries—Across the entire functional range of charge

Lithium–graphite intercalation compounds (Li-GICs) are by far the most common anode material for modern Li-ion batteries. However, the dielectric response of this material in the electrostatic limit and its variation depending on the state of charge (SOC) has not been investigated to a satisfactory degree – neither by means of theory nor by experiment – and especially not for the higher range of SOC. In this work, we – for the first time – predict a mostly linear dependency of the relative permittivity ϵr on the SOC, from ≈7 at SOC 0% to ≈25 at SOC 100%. This is achieved by making use of our recently published DFTB parametrization for Li-GICs based on a machine-learned repulsive potential in order to overcome the computational hurdles of sampling the long-ranged Coulomb interactions within this material. In doing so, we provide novel insight into a property which is highly desired, particularly as an input parameter for charged kinetic Monte Carlo simulations.