Anode For Lithium-ion Batteries Research Articles

High-conductivity and elasticity interface consisting of Li-Mg alloy and Li3N on silicon for robust Li-ion storage

Silicon (Si) materials are one of the industry's preferred choices for lithium-ion batteries (LIBs) anode in the near and mid-term due to their high theoretical capacity, abundance in earth and safety. However, the weak and low conductivity of the solid electrolyte interface (SEI) leads to poor cycling stability, limited Coulombic efficiency, and poor rate performance, consequently hampering practical applications. Herein, the MgSiN2 functional coating is prepared by in-situ evolution of Mg2Si on porous micro-Si (pMSi@MgSiN2) via a scalable one-step low-temperature nitriding strategy. Interestingly, MgSiN2 is converted into the robust multi-functional interface composed of highly conductive Li3N and elastic Li-Mg alloy during subsequent lithium intercalation, which is studied by in-situ/ex-situ methods. The multi-functional interface takes over the role of improving interfacial stability and ionic/electronic conductivity. As expected, the pMSi@MgSiN2 anode shows a high gravimetric capacity of 1981.5 mAh g−1 at 1.0 A g−1 after 150 cycles, together with a high initial Coulombic efficiency of over 88.4 %. Furthermore, a consider capacity of 894 mAh g−1 can be retained after 500 cycles at 5.0 A g−1. The results and strategy reveal a new route for the integrated design of Si interface or other alloy-type anode materials to the fast lithium storage performance.

Lightweight Carbon-Metal-Based Fabric Anode for Lithium-Ion Batteries.

Lithium-ion battery electrodes are typically manufactured via slurry casting, which involves mixing active material particles, conductive carbon, and a polymeric binder in a solvent, followed by casting and drying the coating on current collectors (Al or Cu). These electrodes are functional but still limited in terms of pore network percolation, electronic connectivity, and mechanical stability, leading to poor electron/ion conductivities and mechanical integrity upon cycling, which result in battery degradation. To address this, we fabricate trichome-like carbon-iron fabrics via a combination of electrospinning and pyrolysis. Compared with slurry cast Fe2O3 and graphite-based electrodes, the carbon-iron fabric (CMF) electrode provides enhanced high-rate capacity (10C and above) and stability, for both half cell and full cell testing (the latter with a standard lithium nickel manganese oxide (LNMO) cathode). Further, the CMFs are free-standing and lightweight; therefore, future investigation may include scaling this as an anode material for pouch cells and 18,650 cylindrical batteries.

Reduced Volume Expansion of Micron-Sized SiOx via Closed-Nanopore Structure Constructed by Mg-Induced Elemental Segregation.

The inherently huge volume expansion during Li uptake has hindered the use of Si-based anodes in high-energy lithium-ion batteries. While some pore-forming and nano-architecting strategies show promises to effectively buffer the volume change, other parameters essential for practical electrode fabrication, such as compaction density, are often compromised. Here we propose a new in situ Mg doping strategy to form closed-nanopore structure into a micron-sized SiOx particle at a high bulk density. The doped Mg atoms promote the segregation of O, so that high-density magnesium silicates form to generate closed nanopores. By altering the mass content of Mg dopant, the average radii (ranged from 5.4 to 9.7 nm) and porosities (ranged from 1.4 % to 15.9 %) of the closed pores are precisely adjustable, which accounts for volume expansion of SiOx from 77.8 % to 22.2 % at the minimum. Benefited from the small volume variation, the Mg-doped micron-SiOx anode demonstrates improved Li storage performance towards realization of a 700-(dis)charge-cycle, 11-Ah-pouch-type cell at a capacity retention of >80 %. This work offers insights into reasonable design of the internal structure of micron-sized SiOx and other materials that undergo conversion or alloying reactions with drastic volume change, to enable high-energy batteries with stable electrochemistry.

Heterostructured ZnS/Co embedded in pinecone-like N/S-doped carbon for efficient sodium/lithium storage

Constructing heterogeneous electrodes to confront various electrochemical and structural requirements is demonstrated to be crucial for improving the sodium and lithium storage performances. Herein, a novel design of ZnS/Co heterostructures is expounded with abundant phase boundaries encapsulated in highly-conductive N/S-doped “pinecone”-like carbon framework (ZnS/Co@NSC-450) as a superior anode for sodium ion batteries (SIBs) and lithium-ion batteries (LIBs). In ZnS/Co@NSC-450, the ZnS/Co heterostructures can improve the electronic conductivity of material and stabilize the electrode structure integrity during cycling, while the N/S-doped “pinecone”-like carbon is beneficial for alleviating the volume expansion effect of active materials, providing additional active sites for sodium/lithium storage and ensuring the rapid electron/ion transfer across the electrode. Due to the synergistic effect of multiple components, both the SIBs and LIBs with ZnS/Co@NSC-450 anodes exhibit high-rate capability (476 mAh g−1 at 6.4 A g−1 for SIBs and 387 mAh g−1 at 12.8 A g−1 for LIBs) and outstanding long-term cycling stability (557 mAh g−1 at 2 A g−1 for SIBs after 1500 cycles and 767 mAh g−1 for LIBs after 1000 cycles). These results disclose the promising potential of ZnS/Co@NSC-450 toward high-performance SIBs and LIBs.

Engineering of Cerium Modified TiNb2O7 Nanoparticles For Low-Temperature Lithium-Ion Battery.

Although TiNb2O7 (TNO) with comparable operating potential and ideal theoretical capacity is considered to be the most ideal replacement for negative Li4Ti5O12 (LTO), the low ionic and electronic conductivity still limit its practical application as satisfactory anode for lithium-ion batteries (LIBs) with high-power density. Herein, TNO nanoparticles modified by Cerium (Ce) with outstanding electrochemical performance are synthesized. The successful introduction of Ce3+ in the lattice leads to increased interplanar spacing, refined grain size, more oxygen vacancy, and a smaller lithium diffusion barrier, which are conducive to improve conductivity of both Li+ and electrons. As a result, the modified TNO reaches high reversible capacity of 256.0mAhg-1 at 100mAg-1 after 100cycles, and 183.0mAhg-1 even under 3200mAg-1. In particular, when the temperature drops to -20°C, the cell undergoing 1500cycles at a high current density of 500mAg-1 can still reach 89.7mAhg-1, corresponding to a capacity decay rate per cycle of only 0.033%. This work provides a new way to improve the electrochemical properties of alternative anodes for LIBs at extreme temperature.

Defect Engineering Boosting High‐Performance Graphite Anode for Sodium‐Ion Batteries in Ether‐Based Electrolytes

Sodium‐ion batteries (NIBs) as one of the next‐generation energy storage devices are gradually used in energy field and entering lithium‐ion batteries (LIBs) market. Graphite with low price exhibits excellent Li+ reversible intercalation properties, which has been widely applied in anodes of LIBs. But it has low capacity for sodium because of its weak chemical bonding with sodium. Here, a defect engineered graphite with low graphitization structure is reported. This graphite demonstrates a defect adsorption and solvated ion intercalation of sodium ions by introducing more active sites and ether electrolytes, effectively improving the storage capacity of sodium. Further experiments and characterization show defects increased after ball milling with surface area increased, and the favorable defects on the interface of graphite are significantly increased. The defect engineered graphite absorbs more sodium‐ions and exhibits capacitive characteristics with fast sodiation/desodiation process, leading to an improved capacity storage than the defect‐free graphite. Meanwhile, the defect engineered graphite can deliver a capacity of 175 mAh g−1, and maintain a good capacity retention of 84% at 5 A g−1 after 6000 cycles. This work discovers a general methodology to obtain defect engineered graphite, which will provide an experimental strategy to achieve large‐scale industrialization for low‐cost NIBs.

Cobalt vacancy boosting Co3-xO4@C with superior pseudocapacitive lithium storage

The Co3O4 as anode for lithium ion batteries (LIBs) suffers the sluggish electrode kinetics and severe capacity fade during the cycles. The defective engineering of Co3O4 with oxygen/cobalt defects is an effective strategy to optimize Co3O4 with enhanced electrochemical properties. Herein, a series of 3D inter-connected Co3-xO4@C-y nanostructures with abundant Co defects are synthesized through a hydrothermal approach with subsequent heating-controlled process. Benefiting from its rich surface cobalt-defective sites and the 3D interconnected frameworks, as well as its high surface area and residual carbon layer, the Co3-xO4@C-y synthesized at y = 400 °C as anode for LIBs displays superior pseudocapacitive lithium storage properties with an ultra-high reversible specific capacity of 1900.7 mAh g−1 at 0.2 A g−1, excellent rate capability (e.g., 1415.1 mAh g−1 at 10 A g−1) and ultra-long cycling stability (e.g., 1160.5 mAh g−1 at 15 A g−1 after 2000 cycles).

Large-Scale Synthesis of Highly Porous CuO/Cu2O/Cu/Carbon Derived from Aerogels for Lithium-Ion Battery Anodes.

In this work, an effective strategy for the large-scale fabrication of highly porous CuO/Cu2O/Cu/carbon (P-Cu-C) has been established. Cu-cross-linked aerogels were first continuously prepared using a continuous flow mode to form uniform beads, which were transformed into P-Cu-C with a subsequent pyrolysis process. Various pyrolysis temperatures were used to form a series of P-Cu-C including P-Cu-C-250, P-Cu-C-200, P-Cu-C-350, and P-Cu-C-450 to investigate suitable pyrolysis conversion processes. The obtained P-Cu-C series were utilized as anodes of lithium-ion batteries, in which P-Cu-C-250 exhibited a higher reversible gravimetric capacity, excellent rate capability, and superior cycle stability. The enhanced behavior of P-Cu-C-250 was benefitted from the synergistic interaction between uniformly dispersed CuO, Cu2O, Cu nanoparticles, and highly graphitized carbon with a large surface area and highly porous structure. More importantly, the preparation of P-Cu-C-250 could be scaled up by taking advantage of the continuous flow synthesis mode, which may provide pilot- or industrial-scale applications. The large-scale fabrication proposed here may give a universal method to fabricate highly porous metal oxide-carbon anode materials for electrochemical energy conversion and storage applications. Porous CuO/Cu2O/Cu/carbon derived from Cu-crosslinked aerogels was used as Li-ion battery anode materials, exhibiting a high reversible areal capacity, large gravimetric capacity, superior cycling performance, and excellent rate capacity. A continuous preparation method is established to ensure the product scaled up.

Enhanced diffusion kinetics in Y-doped SnO2 anodes for low-temperature lithium-ion batteries: A combined theoretical and experimental study

In recent years, there has been an increasing demand for lithium-ion batteries suitable for low temperatures in various fields. SnO2, with its high theoretical specific capacity, has emerged as an ideal candidate for low-temperature lithium-ion batteries. However, tin oxide exhibits inherent issues such as poor conductivity and limited cycle reversibility. Enhancing the diffusion rate of lithium ions in tin oxide is crucial for improving its low-temperature performance. We use first-principles calculations based on Density Functional Theory (DFT) to investigate the doping models of various transition metal elements (Sc, Y, Ti, Zr, V, Nb, Gr, Mo, Mn, Fe, Co, Ni) with a rational ratio of 4 % in SnO2. The results indicate that Y doping decreases the band gap of SnO2 by 0.253 eV, leading to a significant reduction in the Li-ion diffusion barrier of α-Sn. Furthermore, the synthesized SnO2 doped with Y (Y-SnO2) electrode exhibited excellent cyclic stability as an anode and achieved a high reversible capacity of 672 mAh g−1 at −10°C, surpassing that of the pure SnO2 (450 mAh g−1). Moreover, it demonstrated a higher diffusion coefficient of lithium ions and lower charge transfer impedance at both low and room temperatures.

One Precursor, Two Different Outcomes: SnO-Graphite Composite and Anion-Doped SnO2 with Ester Surface Functionality.

The technological importance of SnO2 and SnO has invited scientists to explore various aspects, including their synthesis in the nanosize regime, surface functionalization, and composite formation. In the present work, a binuclear Sn2-EDTA complex has been demonstrated to produce a SnO-graphite composite and C, N-codoped SnO2 nanocrystals with ester functionality in quantitative yields by thermal and solvothermal dissociation processes. The products were characterized extensively. While SnO in the SnO-graphite composite exhibited tetragonal symmetry, graphitic carbon had defects. The composite had 12 wt % of graphitic carbon. The role of the SnO-graphite composite as an anode in lithium-ion batteries (LIB) has been evaluated. Solvothermal dissociation of the Sn2-EDTA complex in a propylene glycol medium yielded nanocrystalline SnO2 with yellow color. Agglomerated crystallites had ester functionality on their surfaces. The surface functionality was thermally stable up to 200 °C, and its complete removal yielded tetragonal white-colored SnO2. Co-doping of carbon and nitrogen in yellow SnO2 reduced its optical band gap (2.9 eV). Despite the negative surface charge of the functionalized SnO2, its affinity to rapidly adsorb anionic azo dyes (Congo red and Eriochrome black T) from aqueous solutions has been validated. Following pseudo-second-order kinetics, adsorption data analysis revealed chemisorption as the primary driving force in this process.

A Gradient Composite Structure Enables a Stable Microsized Silicon Suboxide-Based Anode for a High-Performance Lithium-Ion Battery.

The practical application of microsized anodes is hindered by severe volume changes and fast capacity fading. Herein, we propose a gradient composite strategy and fabricate a silicon suboxide-based composite anode (d-SiO@SiOx/C@C) consisting of a disproportionated microsized SiO inner core, a homogeneous composite SiOx/C interlayer (x ≈ 1.5), and a highly graphitized carbon outer layer. The robust SiOx/C interlayer can realize a gradient abatement of stress and simultaneously connect the inner SiO core and carbon outer layer through covalent bonds. As a result, d-SiO@SiOx/C@C delivers a specific capacity of 1023 mAh/g after 300 cycles at 1 A/g with a retention of >90% and an average Coulombic efficiency of >99.7%. A full cell assembled with a LiNi0.8Co0.15Al0.05O2 cathode displays a remarkable specific energy density of 569 Wh/kg based on total active materials as well as excellent cycling stability. Our strategy provides a promising alternative for designing structurally and electrochemically stable microsized anodes with high capacity.

Engineering Nano-Sized Silicon Anodes with Conductive Networks toward a High Average Coulombic Efficiency of 90.2% via Plasma-Assisted Milling.

Si-based anode is considered one of the ideal anodes for high energy density lithium-ion batteries due to its high theoretical capacity of 4200 mAh g-1. To accelerate the commercial progress of Si material, the multi-issue of extreme volume expansion and low intrinsic electronic conductivity needs to be settled. Herein, a series of nano-sized Si particles with conductive networks are synthesized via the dielectric barrier discharge plasma (DBDP) assisted milling. The p-milling method can effectively refine the particle sizes of pristine Si without destroying its crystal structure, resulting in large Brunauer-Emmett-Teller (BET) values with more active sites for Li+ ions. Due to their unique structure and flexibility, CNTs can be uniformly distributed among the Si particles and the prepared Si electrodes exhibit better structural stability during the continuous lithiation/de-lithiation process. Moreover, the CNT network accelerates the transport of ions and electrons in the Si particles. As a result, the nano-sized Si anodes with CNTs conductive network can deliver an extremely high average initial Coulombic efficiency (ICE) reach of 90.2% with enhanced cyclic property and rate capability. The C-PMSi-50:1 anode presents 615 mAh g-1 after 100 cycles and 979 mAh g-1 under the current density of 5 A g-1. Moreover, the manufactured Si||LiNi0.8Co0.1Mn0.1O2 pouch cell maintains a high ICE of >85%. This work may supply a new insight for designing the nano-sized Si and further promoting its commercial applications.

Direct and rapid thermal shock for recycling spent graphite in lithium-ion batteries

Due to the rapid increase in the number of spent lithium-ion batteries, there has been a growing interest in the recovery of degraded graphite. In this work, a rapid thermal shock (RTS) strategy is proposed to regenerate spent graphite for use in lithium-ion batteries. The results of structural and morphological characterization demonstrate that the graphite is well regenerated by the RTS process. Additionally, an amorphous carbon layer forms and coats onto the surface of the graphite, contributing to excellent rate performance. The regenerated graphite (RG-1000) displays excellent rate performance, with capacities of 413 mAh g−1 at 50 mA g−1 and 102.1 mAh g−1 at 1000 mA g−1, respectively. Furthermore, it demonstrates long-term cycle stability, maintaining a capacity of 80 mAh g−1 at 1000 mA g−1 with a capacity retention of 78.4 % after 600 cycles. This RTS method enables rapid and efficient regeneration of spent graphite anodes for lithium-ion batteries, providing a facile and environmentally friendly strategy for their direct regeneration.

High-Rate Performance of a Designed Si Nanoparticle–Graphite Nanosheet Composite as the Anode for Lithium-Ion Batteries

A silicon nanoparticle–graphite nanosheet composite was prepared via a facile ball milling process for use as the anode for high-rate lithium-ion batteries. The size effect of Si nanoparticles on the structure and on the lithium-ion battery performance of the composite is evaluated. SEM and TEM analyses show a structural alteration of the composites from Si nanoparticle-surrounded graphite nanosheets to Si nanoparticle-embedded graphite nanosheets by decreasing the size of Si nanoparticles from 250 nm to 40 nm. The composites with finer Si nanoparticles provide an effective nanostructure containing encapsulated Si and free space. This structure facilitates the indirect exposure of Si to electrolyte and Si expansion during cycling, which leads to a stable solid–electrolyte interphase and elevated conductivity. An enhanced rate capability was obtained for the 40 nm Si nanoparticle–graphite nanosheet composite, delivering a specific capacity of 276 mAh g−1 at a current density of 1 C after 1000 cycles and a rate capacity of 205 mAh g−1 at 8 C.

Lithium transfer dynamics and storage capacity/cyclability properties of Ni and Ru dual-doped two-dimensional FePS3 nanoflakes

Despite owning a high theoretical lithium ion capacity, the iron phosphorus trisulfide FePS3 writhes from inferior cyclability and lower reaction kinetics to be employed as a potential anode in lithium ion batteries. Herein, we demonstrate a dual-doping approach with nickel and ruthenium in optimal quantities leading to the formation of Ni0.07Ru0.03-FePS3 two dimensional layers (flakes) having high electrochemical conductivity and increased cyclability. This comprehensive investigation unravels the influence of single and dual doping of isovalent (Ni2+) and aliovalent (Ru3+) ions on the lithium intercalation/deintercalation kinetics in FePS3. The Ni increases active intercalation sites and enhances electrical conductivity while Ru influences the Li+ ion kinetics by increasing the channel width, termed as pillar effect. Theoretical calculations indicate the improved binding of lithium on Ni and Ru dual-doped FePS3. Ni0.07Ru0.03-FePS3 based anode offers a high discharge-capacity ∼600mAhg−1 (∼450 mAhg−1) at a high current rate of 1 Ag−1 (10 Ag−1) showcasing an approximate six-fold improvement from FePS3 (∼104 mAhg−1). The high coulombic efficiency (∼95 %) and high rate performance with improved cyclability obtained with the LiFePO4/Ni0.07Ru0.03-FePS3 full-cell indicate the synergistic effects of dual doping. This opens a plethora of opportunities in developing high-capacity and high-cyclability anodes by engineering the metal trichalcogenides through dual doping.

Understanding the capacity increase mechanism in MoO2/C anodes for Lithium-Ion batteries

A facile and eco-friendly hydrothermal method, which does not employ surfactants, is used to synthesize MoO2/C as an anode material for lithium-ion batteries. Our approach overcomes kinetic barrier associated with the conversion reaction. The morphological analysis reveals that primary particles of MoO2/C are individual crystals forming secondary nanoparticles, which aggregate into tertiary micron-sized particles. This unique morphology plays a crucial role in enhancing the kinetics of lithium storage. It facilitates a gradual conversion reaction during the cycling process, even at ambient temperatures. The gradual nature of the conversion reaction of MoO2 upon cycling is clearly evidenced from the observed morphologies. These findings are comprehensively supported by thorough electrochemical investigations and analyses, which combined demonstrate the structural and electrochemical properties of the produced MoO2/C.

Formation of hollow spheres structures Co/CoO/ZnO@NC from metal-organic frameworks as a anode for lithium-ion batteries

Transition metal oxides have become a potential anode material for LIBs due to their large theoretical capacity, low cost, abundant resources. However, significant volume changes and severe particle aggregation occur during charge/discharge process. In this work, it is found that the composite of dual component active TMO and single metal, and coating by doped carbon are the effective methods to improve the electrochemical performance and adapt to volume changes in storing lithium. The specific process is based on the co-precipitation of Zn and Co ions in the presence of 2-methylimidazolium salts to produce imidazolium salt frameworks (ZIFs) of bimetallic zeolites, which are then thermally decomposed to form hollow spheres structures Co/CoO/ZnO@NC. The hollow sphere uses Co as the core and CoO/ZnO@NC particles coated with nitrogen doped carbon layer as the shell. These spherical structures exhibit excellent electrochemical performance, high reversible capacity, excellent cycling stability (702 mAh/g at 100 mAg−1 after 100 cycles), and good rate capability (735 mAh/g and 515 mAh/g at 100 mA g−1 and 2000 mA g−1 respectively).

A simple and effective approach to relieve stress and enhance cyclability of Si-based materials toward high-energy lithium-ion batteries

Silicon-based materials are promising anodes to keep up with the demands for next-generation lithium-ion batteries in the coming decades owing to their ultrahigh theoretical capacities. However, the severe volume changes and mechanical fractures during cycling greatly hinder their way to commercialization. So far, it still remains a great challenge to develop advanced Si-based electrodes with high mechanical stability and remarkable electrochemical properties. In this work, we propose a simple and effective strategy to encapsulate Si@SiOx particles into B, N co-doped carbon nanotubes (BNCNTs) to develop Si@SiOx@BNCNT electrode for enhanced lithium storage. The SiOx layer upon Si particle is designed to mitigate the volume expansion of Si and maintain the particle integrity. Finite element analysis demonstrates that BNCNTs with high mechanical strength can further relieve the internal stress induced by Si expansion upon lithiation. The double restraint effect from SiOx layers and BNCNTs on the Si particles contributes to excellent resistance to structural degradation, enabling high stability and desirable electrochemical performance of Si@SiOx@BNCNT electrode. This strategy provides great opportunities for the practical application of Si-based anodes in high-energy lithium-ion batteries.

Scalable Synthesis of Si Nanosheets as Stable Anodes for Practical Lithium-Ion Batteries.

Silicon (Si) is regarded as a promising anode material because of its outstanding theoretical capacity, abundant existence, and mature infrastructure, but it suffers from an inherent volume expansion problem. Herein, a facile, scalable, and cost-effective route to produce Si nanosheets (Si NSs) using a low-cost silica fume as the start materials is proposed. After coated with carbon, the as-prepared Si-NSs@C material delivers ultrahigh capability (2770mAhg-1 at 0.1C), high initial Coulombic efficiency (87.9%), and long cycling lifespan (100 cycles at 0.5C with a capacity decay rate of 0.3% per cycle). Beyond proof of concept, this work demonstrates a Si-NSs based pouch cell with an impressive capacity retention of 70.9% after 400 cycles, making it more promising for practical application. Revealed by the theoretical simulation, kinetics analysis, and in situ thickness/pressure detection, it is found that the superior performance of Si-NSs is attributed to the improved diffusivity and reversibility of Li+ ions and low expansion.

First-principles prediction of one-dimensional conductive metallic organic polymers as ultrahigh energy density anode for lithium-ion batteries.

Metal-Organic Polymers (MOPs) have attracted growing attention for lithium-ion battery (LIB) applications due to their merits in orderly ionic transportation and robust structure stability in electrochemical reactions. However, they suffer from poor electronic conductivity. In this work, we apply first-principles density functional theory to explore the potential of three one-dimensional (1D) electrically conductive C6H2S4TM (TM = Fe, Co, and Ni) MOPs with the π-d conjugated coordination as anode materials for Li+ ions storage. Our theoretical results reveal that these 1D MOPs possess a superior theoretical capacity of over 748 mA h g-1. In particular, the 1D C6H2S4Ni MOP shows an exceptional theoretical specific capacity of 1110 mA h g-1 based on the three-electron transferring reaction, which significantly outperforms the traditional graphite-based anode material in LIBs. Moreover, the resonant charge transfer between Ni metal and ligand within the 1D C6H2S4Ni MOP reduces the diffusion energy barrier of the Li atoms when they migrate on the surface of the MOP. The ultrahigh theoretical specific capacity of the C6H2S4Ni MOP predicts that it can be a promising anode material for LIBs.