Performance Of Li-ion Batteries Research Articles

Synergistic boost in Fe3O4 anode performance for li-ion batteries via Zn and Cu double doping and multi-walled carbon nanotube composite integration

In this study, a novel nanocomposite material comprising pure Fe3O4 (FO), doped Zn0.5Cu0.5Fe2O4-3 (ZCFO-3), and Zn0.5Cu0.5Fe2O4-3@ Multi-walled carbon nanotube (ZCFO-3@MWCNT) nanocomposite material is carefully prepared using a simple one-step hydrothermal process. Comprehensive surface and morphological analysis are conducted using X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), and High-resolution transmission electron microscopy (HRTEM), while compositional studies are investigated through Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The electrochemical performance is fully analyzed through Cyclic voltammetry (CV), Electrochemical impedance spectroscopy (EIS), rate capability tests, discharge/charge capacity, and cyclic stability evaluations. Among these three nanomaterials, ZCFO-3@MWCNT nanocomposite at 100 mA g−1 current density reveals the best performance, with a discharge capacity of 1974 mAh g–1, ZCFO-3 and FO reveal 1340 mAh g–1 and 1317 mAh g–1 respectively. After 800 cycles at 500 mA g−1 current density, ZCFO-3@MWCNT stays strong with a discharge capacity of 646 mAh g–1, while ZCFO-3 manages only 362 mAh g–1 and FO only 111 mAh g–1. After 1200 cycles at 500 mA g−1, the nanocomposite still delivers 518 mAh g–1. This study suggests that ZCFO-3@MWCNT could be a promising anode material for lithium-ion batteries.

Enhanced cycle performance of Li ion battery by graphene sheets covering with SnO@SnO2 anode materials

Enhanced cycle performance of Li ion battery by graphene sheets covering with SnO@SnO2 anode materials

Lithium fluorosulfonate-induced low-resistance interphase boosting low-temperature performance of commercial graphite/LiFePO4 pouch batteries

The performance of Li-ion batteries (LIBs) at sub-ambient temperatures is limited by the resistive interphases due to electrolyte decomposition, particularly on the anode surface. In this study, lithium fluorosulfonate (LFS) was added to commercial electrolytes to enhance the low-temperature electrochemical performance of LiFePO4 (LFP)/graphite (Gr) pouch cells. The addition of LFS significantly reduced the charge transfer resistance of the anode, substantially extending the cycle life and discharge capacity of commercial LFP/Gr pouch cells at −10 and −30 °C. Compared with the capacity retention rate of the baseline electrolyte at −10 °C (80 % after 25cycles), the capacity retention rate of the LFS electrolyte after 100 cycles under 0.5 C/0.5 C was retained at 94 %. Further mechanistic studies showed that the LFS additive induced the formation of a solid electrolyte interphase (SEI) film comprising inorganic-rich LiF, Li2SO4, and additional organic fluorides and sulfides to maintain good stability at the Gr/electrolyte interface during low-temperature operation. LFS suppressed electrolyte decomposition by forming a robust and low-resistance SEI film on the anode. These results demonstrate that LFS is a promising electrolyte additive for low-temperature LFP/Gr pouch cells.

Mg-Composition Dependent Cycle Stability in Zn<sub>1-x</sub>Mg<sub>x</sub>O Li-ion Battery: Transition from Electronic Transport-Limited to Ionic Transport Limited Cycles

This study explores Mg-composition dependent cycle stability in a Zn<sub>1-x</sub>Mg<sub>x</sub>O Li-ion battery, where battery cycles transition from an electronic transport-limited to an ionic transport limited regime. We investigated the impact of Mg doping in Zn<sub>1-x</sub>Mg<sub>x</sub>O nanocrystals on Li-ion battery performance, focusing on Mg compositions between x=0.05 and x=0.15. Mg composition dependent structural and electrical properties were explored using field effect transistors (FETs) and various microscopic/spectroscopic methods. The electronic conductivity was found to be sensitive to changes in Mg composition. Consistently, the initial capacity decreased with an increase in Mg composition, aligning with the reduction in electronic conductivity due to Mg doping. However, with successive cycles, the capacity became independent of the electronic conductivity, an outcome attributed to the formation of a solid-electrolyte interphase (SEI) and the conversion reactions. Initially, Mg doping reduces electronic conductivity due to increased carrier trapping, leading to lower discharge capacity. However, as cycling progresses, the impact of Mg doping diminishes. The formation of the SEI layer becomes more influential, significantly affecting Li-ion transport. Over time, factors like SEI formation, conversion reaction dynamics, and structural changes within the electrode start to dominate the battery's capacity, rather than the initial electronic conductivity influenced by Mg doping. This understanding can guide the development of materials with lower resistance, facilitating faster charging and discharging rates. More importantly, this study indicates that the initial capacity is closely tied to the conductivity of the Zn<sub>1-x</sub>Mg<sub>x</sub>O material.

Unveiling potential of thiophene-functionalized C3N3 nanosheet as an anode for Li-ion batteries: A DFT-D3 study

Covalent triazine frameworks (CTFs) are a fascinating type of porous organic materials that exhibit numerous distinct features, such as significant specific surface area, outstanding chemical/thermal stability, and structural modifiability at the molecular level. These features make CTFs highly appealing for utilization in Li-ion batteries (LIBs). However, their low electronic conductivity limits their practical applications. In the present study, the potential anode application of thiophene-functionalized C3N3 nanosheet for LIBs was conducted by dispersion-corrected density functional theory (DFT-D3) calculations. It was found that functionalization of the C3N3 nanosheet with six thiophene groups ((THP)6@C3N3) led to the highest reduction (0.19 eV) in the energy gap of the pristine C3N3 nanosheet. A single Li-ion preferably adsorbs between two nitrogen atoms of the triazine ring with an adsorption energy of about 4.59 eV. The absorption of Li-ion resulted in a reduction of the band gap from 1.37 eV to 0.43 eV, indicating enhanced electrical conductivity and superior cycle stability. The fully loaded functionalized nanosheet with nineteen Li-ions at various adsorption sites exhibited a remarkable theoretical specific capacity of 526.55 mAh/g. This configuration also displayed a low open-circuit voltage (0.09 V) and diffusion energy barrier (0.35 eV), ideal as an anode with a rapid charging/discharging rate. Therefore, thiophene-functionalized C3N3 nanosheet demonstrates superior anode performance for LIBs due to its high theoretical specific capacity, small diffusion barrier, and low working voltage. This work can provide insights for the refere development of CTF-based anode materials.

Correction: Enhanced cycle performance of Li ion battery by graphene sheets covering with SnO@SnO2 anode materials

Correction: Enhanced cycle performance of Li ion battery by graphene sheets covering with SnO@SnO2 anode materials

Revisiting the Effect of Natural and Artificial Graphite on the Performance of Ni-rich Li-ion Batteries at Coin and Cylindrical Cells

We conducted a detailed evaluation of the electrochemical performance of artificial graphite (AG) and natural graphite (NG) from four leading global companies: AG-1, AG-2, AG-3, and NG-4 towards Ni-rich Li-ion batteries. We found that AG-2, an artificial graphite variant, demonstrated superior performance with exceptional capacity, rapid charging capabilities, and impressive capacity retention. AG-2 achieved a specific capacity of 338.97 mAh g−1, outperforming AG-1 (321.16 mAh g−1), AG-3 (314.43 mAh g−1), and NG-1 (328.08 mAh g−1). This superiority was further confirmed by high C-rate tests ranging from 2 C to 5 C. Notably, after 500 cycles, AG-2 maintained 91.18% of its initial capacity, significantly surpassing AG-1 (89.44%), AG-3 (78.78%), and NG-1 (84.16%). The study attributes AG-2’s exceptional performance to its refined properties such as smaller particle size, fewer graphite imperfections, and a higher 2H phase content. These characteristics lead to increased active material in the anode, enhancing battery capacity, and to less material degradation over time, ensuring consistent capacity retention. Overall, AG-2 stands out as a highly efficient and cost-effective option for lithium-ion battery applications, eclipsing other commercial graphite alternatives.

Analysis of Trace Impurities in Lithium Carbonate.

Lithium carbonate (Li2CO3) is a critical raw material in cathode material production, a core of Li-ion battery manufacturing. The quality of this material significantly influences its market value, with impurities potentially affecting Li-ion battery performance and longevity. While the importance of impurity analysis is acknowledged by suppliers and manufacturers of battery materials, reports on elemental analysis of trace impurities in Li2CO3 salt are scarce. This study aims to establish and validate an analytical methodology for detecting and quantifying trace impurities in Li2CO3 salt. Various analytical techniques, including X-ray diffraction (XRD), scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDX), X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma optical emission spectroscopy (ICP-OES), were employed to analyze synthetic and processed lithium salt. X-ray diffraction patterns of Li2CO3 were collected via step-scanning mode in the 5-80° 2θ range. SEM-EDX was utilized for particle morphology and quantitative impurity analysis, with samples localized on copper tape. XPS equipped with a hemispherical electron analyzer was employed to analyze the surface composition of the salt. For ICP-OES analysis, a known amount of lithium salt was subjected to acid digestion and dilution with ultrapure water. Multielemental standard solutions were prepared, including elements such as Al, Cd, Cu, Fe, Mn, Ni, Pb, Si, Zn, Ca, K, Mg, Na, and S. Results confirmed the presence of the zabuyelite phase in XRD analysis, corresponding to the natural form of lithium carbonate. SEM-EDX mapping revealed impurities of Si and Al, with low relative quantification values of 0.12% and 0.14%, respectively. XPS identified eight potential impurity elements, including S, Cr, Fe, Cl, F, Zn, Mg, and Na, alongside Li, O, and C. Regarding ICP-OES analysis, performance parameters such as linearity, limit of detection (LOD), and quantification (LOQ), variance, and recovery were evaluated for analytical validation. ICP-OES results demonstrated high linearity (>0.99), with LOD and LOQ values ranging from 0.001 to 0.800 ppm and 0.003 to 1.1 ppm, respectively, for different elements. The recovery rate exceeded 90%. In conclusion, the precision of the new ICP-OES methodology renders it suitable for identifying and characterizing Li2CO3 impurities. It can effectively complement solid-state techniques such as XRD, SEM-EDX, and XPS.

Multi-interest adaptive unscented Kalman filter based on improved matrix decomposition methods for lithium-ion battery state of charge estimation

Accurately predicting the state of charge (SOC) is crucial to improving Li-ion battery performance. However, available model-based estimation approaches still face challenges in handling model uncertainty and measurement noise effects on parameter identification. Besides, the widely used unscented Kalman filter (UKF) algorithm has limitations in electric vehicles as it requires the error covariance matrix to maintain positive definiteness, limiting its applicability under certain conditions. This study introduces the bias-compensated forgetting factor recursive least squares (BCFFRLS) method for parameter estimation within the second-order RC equivalent circuit model specific to the INR18650-20R battery. Furthermore, we propose a novel algorithm named the optimization multi-interest adaptive unscented Kalman filter (O-MIAUKF). This algorithm is designed to address stability and robustness issues with traditional UKF encounters in dynamic environments. Experimental validation demonstrates that the O-MIAUKF algorithm excels in maintaining strong stability and robustness in various working conditions, accurately estimating SOC even with a non-positive covariance matrix. The SOC estimation error remains stable at 0.8 %, which is lower than that of the current Extended Kalman Filter (EKF), UKF, and Dual Extended Kalman Filter (DEKF).

Electrolyte Dependence of Li+ Transport Mechanisms in Small Molecule Solvents from Classical Molecular Dynamics.

As demands on Li-ion battery performance increase, the need for electrolytes with high ionic conductivity and a high Li+ transference number (tLi) becomes crucial to boost power density. Unfortunately, tLi in liquid electrolytes is typically <0.5 due to Li+ migrating via a vehicular mechanism, whereby Li+ diffuses along with its solvation shell, making its diffusivity slower than the counteranion. Designing liquid electrolytes where the Li+ ion diffuses independently of its solvation shell is of significant interest to enhance the transference number. In this work, we elucidate how the properties of the solvent influence the Li+ transport mechanism. Using classical molecular dynamics simulations, we find that a vehicular mechanism can be increasingly preferred with a decreasing solvent viscosity and increasing interaction energy between the solvent and Li+. Thus, a weaker interaction energy can enhance tLi through a solvent-exchange mechanism, ultimately improving Li-ion battery performance. Finally, metadynamics simulations show that in electrolytes where a solvent-exchange mechanism is preferable, the energy barrier to changing the coordination environment of Li+ is much lower than in electrolytes where a vehicular mechanism dominates.

Understanding solid electrolyte interface formation on graphite and silicon anodes in lithium-ion batteries: Exploring the role of fluoroethylene carbonate

This study explores how fluoroethylene carbonate (FEC) influences the solid electrolyte interface (SEI) layer formation during battery cycling process. FEC improves SEI properties, producing a uniform, chemically stable layer enriched with lithium fluoride. This enhances mechanical resilience and electrochemical stability. FEC also suppresses electrolyte deformation and decomposition, maintaining its initial state. The findings highlight the significance and comprehension of electrolyte additives, offering an electrolyte research pathway for improving Li-ion battery performance and durability.

Separator with active coating for fast and stable Li-ion batteries

Li-ion batteries are widely used in various applications, but their performance is limited by the stability and capacity of the separator. Developing a separator that can prevent thermal runaway and provide additional capacity is a significant challenge in battery research. In this study, a novel method of applying a Lithium titanate (LTO) active coating on the separator of Li-ion batteries is proposed. The LTO active coating can participate in electrochemical reactions and provide additional capacity. The active coating also improves the separator stability by preventing thermal shrinkage and enhancing thermal stability. The active coating has little impact on the Li-ion diffusion, and enables fast and stable battery performance at high C rates. The separator with active coating exhibits the highest ionic conductivity of 1.45 mS/cm, the lowest thermal shrinkage of 1.1% at 160 °C, and the highest capacity of 80.2 mAh/g at 15 C among the tested separators. This method offers a simple and effective way to enhance the performance of Li-ion batteries.

Thermally stable poly-aromatic solid electrolyte coated polyethylene membrane as high-performance lithium-ion battery separator

Improving the dimensional stability and electrolyte wettability of polyolefin separators is crucial to enhancing the safety and performance of power lithium-ion batteries (LIBs). In this work, composited separators that significantly improve both thermal stability and solvent wettability are prepared by coating polyaromatic solid electrolyte (sulfonated poly(aryl ether ketone), SPAEK) onto the surface of commercial polyethylene (PE) separators. Interestingly, the coating layer formed by SPAEK with a 60% sulfonation degree exhibits abundant porous structure owing to the polar sulfonic group inducing a retarded phase separation process. The polyelectrolyte coating layer enables both super-electrolyte affinity and higher electrolyte uptake of the composite separator. Moreover, the composited separator presents much better comprehensive properties, including thermal stability and ionic conductivity. As a result, the SPAEK-coated composite separator assembles LiNi0.83Co0.11Mn0.06O2 (NCM811)/Li battery exhibits a higher capacity retention rate of 84.01% at 2 C with a specific capacity of 151.25 mAh g−1 after 200 cycles. Hence, this modified separator is a potential material that facilitates high performance and safety for Li-ion batteries.

Electrochemical Removal of HF from Carbonate-based LiPF6-containing Li-ion Battery Electrolytes

Due to the hydrolytic instability of LiPF6 in carbonate-based solvents, HF is a typical impurity in Li-ion battery electrolytes. HF significantly influences the performance of Li-ion batteries, for example by impacting the formation of the solid electrolyte interphase at the anode and by affecting transition metal dissolution at the cathode. Additionally, HF complicates studying fundamental interfacial electrochemistry of Li-ion battery electrolytes, such as direct anion reduction, because it is electrocatalytically relatively unstable, resulting in a LiF passivation layer. Methods to selectively remove ppm levels of HF from LiPF6-containing carbonate-based electrolytes are limited. We introduce and benchmark a simple yet efficient electrochemical method to selectively remove ppm amounts of HF from LiPF6-containing carbonate-based electrolytes. The basic idea is the application of a suitable potential to a high surface-area metallic electrode upon which only HF reacts (electrocatalytically) while all other electrolyte components are unaffected under the respective conditions.

Collapsed N&S dual-doped carbon nanocages as high-density anode for ultrahigh volumetric performance of Li-ion batteries

Compact lithium-ion batteries for miniaturized devices require high-volumetric-performance anodes. Either the graphite with high density or the porous nanocarbons with high gravimetric performance is limited in volumetric performance. Herein, we construct a series of anode materials, i.e. the collapsed carbon nanocages with different dopants, by capillarity compression, which achieves a high density of ∼0.97 g cm−3 but remains abundant micropores with increased active sites and enlarged interlayer distance. The N&S dual-doping redistributes the charges of sp2 carbon to an optimal status, leading to the high Li-ion capacity, meanwhile facilitates the wettability at the electrode/electrolyte interface, leading to the enhanced Li-ion diffusion coefficient. Accordingly, the collapsed N&S dual-doped carbon nanocages (cNSCNC) anode exhibits a record-high volumetric capacity of 1578 mAh cm−3 at 0.1 A g−1, excellent rate capability and cycling stability, thus achieving an ultrahigh volumetric energy density of 1087 Wh L−1 at 120 W L−1 for the cNSCNC//LiFePO4 full cell.

Comparative Analysis of Commonly Used Machine Learning Approaches for Li-Ion Battery Performance Prediction and Management in Electric Vehicles

The significant role of Li-ion batteries (LIBs) in electric vehicles (EVs) emphasizes their advantages in terms of energy density, being lightweight, and being environmentally sustainable. Despite their obstacles, such as costs, safety concerns, and recycling challenges, LIBs are crucial in terms of the popularity of EVs. The accurate prediction and management of LIBs in EVs are essential, and machine learning-based methods have been explored in order to estimate parameters such as the state of charge (SoC), the state of health (SoH), and the state of power (SoP). Various machine learning techniques, including support vector machines, decision trees, and deep learning, have been employed for predicting LIB states. This study proposes a methodology for comparative analysis, focusing on classical and deep learning approaches, and discusses enhancements to the LSTM (long short-term memory) and Bi-LSTM (bidirectional long short-term memory) methods. Evaluation metrics such as MSE, MAE, RMSE, and R-squared are applied to assess the proposed methods’ performances. The study aims to contribute to technological advancements in the electric vehicle industry by predicting the performance of LIBs. The structure of the rest of the study is outlined, covering materials and methods, LIB data preparation, analysis, the proposal of machine learning models, evaluations, and concluding remarks, with recommendations for future studies.

A Multifunctional Additive Capable of Electrolyte Stabilization and Structure/Interphases Regulation of High‐Energy Li‐Ion Batteries

AbstractNi‐rich cathodes are regarded as the most suitable candidates for high‐energy‐density Li‐ion batteries (LIBs). However, the structural degradation of Ni‐rich cathodes and high reactivity of electrolytes at the high‐potential cathodes greatly affect the cycling stability. One of the prime reasons is that HF produced by the thermal decomposition and hydrolysis of the electrolyte salt LiPF6 can cause corrosion at the electrode/electrolyte interface, promote the transition‐metal dissolution from cathode, and aggravate the decomposition of the electrolyte. This work develops a multifunctional and promising silane‐based electrolyte additive, vinyltrimethylsilane (VTMS), which is generally applicable to Ni‐rich cathode‐based LIBs. Theoretical calculations and practical experiments reveal that VTMS is capable of eliminating HF, stabilizing PF5, and suppressing the hydrolysis of LiPF6. Besides, the additive VTMS undergoes redox reactions prior to other electrolyte components, mitigates the electrolyte decomposition, and constructs superior interphases at both cathode and anode. The electrochemical performance of LIBs is significantly improved at both room temperature (25 °C) and low temperature (0 °C), demonstrating that VTMS has broad application prospects in LIBs. The development of such a multifunctional additive is of great importance for simplifying the electrolyte composition.

Elucidating the Reduction Mechanism of Lithium Bis(oxalato)borate.

Electrolyte additives are indispensable to enhance the performance of Li-ion batteries. Lithium bis(oxalato)borate (LiBOB) has been explored for many years, as it improves both cathode and anode performance. No consensus regarding its reaction mechanisms has, however, been established. A model operando study combining attenuated total reflection infrared spectroscopy (ATR-FTIR), electrochemical quartz crystal microbalance (EQCM), and online electrochemical mass spectrometry (OEMS) is herein presented to elucidate LiBOB reduction and electrode/electrolyte interphases thus formed. Reduction of the BOB- ion sets in at ∼1.8 V with solid lithium oxalate and soluble oxalatoborates as the main products. The reduced BOB- ion also reacts with itself and its environment to evolve CO2, which in turn impacts the interphase formed on the negative electrode. This study provides further insights into the reduction pathways of LiBOB and how they contribute to the interphase formation.

Plasma Surface Treatment of Cu Current Collectors for Improving the Electrochemical Performance of Si Anodes.

The practical utilization of Si electrodes is hindered by their substantial volume expansion during alloying and dealloying processes, which causes mechanical damage and separation from Cu current collectors. To alleviate the problem of Si composite detachment from Cu current collectors, the surface of the Cu current collectors is modified using atmospheric oxygen plasma. Plasma treatment improves the wetting ability of the Cu current collectors and, consequently, the coating quality of the Si electrodes. The uniform distribution of the Si electrode components reduces the sheet resistance and improves the adhesion properties of the Si electrodes containing surface-modified Cu current collectors. As a result, the volume expansion of Si during alloying and dealloying is reduced; this results in an excellent rate capability of 1584 mA h g-1 at a current density of 3.6 A g-1 (135% that of bare Cu) and excellent cycle performance of 1545 mA h g-1 after 300 cycles (Si electrodes with bare Cu exhibit 930 mA h g-1). Therefore, the developed plasma treatment method for Cu current collectors is expected to be an economical and efficient approach for improving the Li-ion battery performance.

F-doped Co-free LiNixMn1-xO2 (0.7 ≤ x ≤ 0.9) cathodes for ameliorating electrochemical performance of Li-ion batteries

Ni-rich LiNiCoMnO2 cathodes, which exhibit high energy densities and layered structures, have been studied For Li-ion batteries (LIBs) with high capacities and excellent stabilities. However, the high cost and price fluctuation of Co as the main element in the cathodes remain severe issues for the stable development of LIBs. Therefore, in this study, F-doped Co-free Ni-rich LiNixMn1-xO2 (0.7 ≤ x ≤ 0.9) cathodes were prepared for high-performance LIBs. With increasing Ni content, the undoped Ni-rich LiNixMn1-xO2 cathodes exhibited increased discharge capacities and decreased stabilities. In contrast, the F-doped Ni-rich LiNixMn1-xO2 cathodes delivered higher cycle retentions at 0.5 C for 100 cycles compared to the undoped cathodes. In addition, the F doping of Ni-rich LiNixMn1-xO2 cathodes can facilitate Li-ion diffusion, retaining their reversibility and high capacities at high current densities.