Rechargeable Li-ion Batteries Research Articles

Optimizing Hard Carbon Anodes from Agricultural Biomass for Superior Lithium and Sodium Ion Battery Performance.

Biomass-derived carbon materials are gaining attention for their environmental and economic advantages in waste resource recovery, particularly for their potential as high-energy materials for alkali metal ion storage. However, ensuring the reliability of secondary battery anodes remains a significant hurdle. Here, we report Areca Catechu sheath-inner part derived carbon (referred to as ASIC) as a high-performance anode for both rechargeable Li-ion (LIBs) and Na-ion batteries (SIBs). We explore the microstructure and electrochemical performance of ASIC materials synthesized at various pyrolysis temperatures ranging from 700 to 1400 °C. ASIC-9, pyrolyzed at 900 °C, exhibits multilayer stacked sheets with the highest specific surface area, and the least lateral size and stacking height. ASIC-14, pyrolyzed at 1400 °C, demonstrates the most ordered carbon structure with the least defect concentration and the highest stacking height and an increased lateral size. ASIC-9 achieves the highest capacities (676 mAh/g at 0.134C) and rate performance (94 mAh/g at 13.4C) for hosting Li+ ions, while ASIC-14 exhibits superior electrochemical performance for hosting Na+ ions, maintaining a high specific capacity after 300 cycles with over 99.5% Coulombic efficiency. This comprehensive understanding of structure-property relationships paves the way for the practical utilization of biomass-derived carbon in various battery applications.

Carbon coated Li3V2(PO4)3 derived from phytic acid with ultra-high rate performance for rechargeable Li ion batteries

The carbon coating strategy has great potential in improving the conductivity of Li3V2(PO4)3 (LVP). However, the preparation of carbon-coated LVP requires an additional carbon source and a complex synthesis process, such as the prereduction of V5+, which poses obstacles to large-scale production. In this article, the phytic acid, a kind of natural biological material with environmental benign and natural abundance, is directly chelated with V3+ and employed as both the phosphorus source and carbon source in the manufacturing procedure of LVP/C material for electrodes. The physical and electrochemical properties of LVP/C material may be tailored by carefully controlling the heat treatment temperature. This process leads to a remarkable boost in key performance metrics, including initial discharge capacity at 1 C (128.35 mAh·g-1), long cycle life at 10 C (115.75 mAh·g-1 after 1000 cycles), and rate capability at 50 C (101.83 mAh·g-1), all attributed to improved electronic conductivity and enhanced ion diffusion kinetics. The simple, novel, and energy-saving method demonstrates great potential for large-scale preparation for the high-performance cathode materials.

Lithium ionic conductivity and structural studies of NASICON structured Li0.4Sr0.3Zr0.5Ti1.5(PO4)3

Stable solid electrolytes have been the subject of intense research due to the growing demand for energy storage and portable energy sources in rechargeable Li-ion batteries. Sodium (NA) super (S) ionic (I) conductor (CON) abbreviated as NASICON are suitable for use as solid electrolytes due to their excellent ionic conductivity and chemical stability. We have reported the effect of partial doping of Sr at Li and Zr4+ at Ti4+ position on the structure and ionic conductivity of composition Li0.4Sr0.3Ti2(PO4)3 (LSTP). The composition with formula Li0.4Sr0.3Ti2−xZrx(PO4)3 (x = 0.0, 0.5, 2.0) were prepared by solid state reaction method. The phase and crystal structure were examined using X-ray diffraction (XRD) patterns. The compositions were in rhombohedral phase with the space group R 3¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\overline{3}$$\\end{document} c. The doping of Zr4+ in LSTP causes the peaks in the XRD spectra for doped composition (x = 0.5, 2.0) to move towards lower angle. The displacement of the XRD peaks towards lower angle side show the expansion in the lattice of the Zr doped compositions Li0.4Sr0.3Ti1.5Zr0.5(PO4)3 and Li0.4Sr0.3Zr2(PO4)3. The presence of stretching and bending modes of PO4 groups in the prepared compositions was identified by FTIR spectra. The enhanced bulk conductivity of 4.32 × 10–5 S/cm for Zr doped composition Li0.4Sr0.3Ti1.5Zr0.5(PO4)3 and 3.20 × 10–5 S/cm for composition Li0.4Sr0.3Zr2(PO4)3 is observed at 25 °C. The modulus peaks in the Zr doped composition Li0.4Sr0.3Ti1.5Zr0.5(PO4)3 is displaced towards higher frequencies at 450 °C, indicating the presence of the thermally produced dielectric relaxation phenomenon and charge carrier hopping. The cole cole plot consisting of one semicircle in case of Li0.4Sr0.3Ti1.5Zr0.5(PO4)3 discusses the contribution of bulk and grain boundary resistances and is fitted by equivalent circuit consisting of CPE and R element joined in parallel.

Green biomediated synthesis of anodized WO3 nanocatalysts using Melia azedarach leaves extract for the energetic transition: Solar hydrogen and Li-ion batteries

This study reports the bio-mediated synthesis of tungsten trioxide nanostructures from aqueous extracts of Melia azedarach (L.) dry leaves. The synthesis was carried out by electrochemical anodization of tungsten foils in the presence of different volume percentages of leaves extracts. These nanostructures were afterwards completely characterized by Field-Emission Scanning Electron Microscopy (FESEM), X-Ray Diffraction (XRD), High-Resolution Transmission Electron Microscopy (HR-TEM), impedance measurements, linear sweep voltammetry in the presence of simulated solar light and UV-Vis spectroscopy. Finally, these nanoelectrodes were used as (photo)electrocatalysts in the photoelectrochemical water splitting process to obtain green hydrogen and as anodes in Li-ion rechargeable batteries. Nanostructures fabricated with 5% M. azedarach leaves extract provided the best (photo)electrocatalytic behavior for both applications, since in that biogenic electrolyte, thin nanorods arranged in very porous and spongy layers were formed. Therefore, the significant increase in specific surface area found for nanostructures fabricated following this green route, in comparison with the blank sample (i.e., nanostructure formed following a non-green route), was essential to enhance their performance as promising efficient (photo)electrocatalysts.

Heavily vanadium-doped LiFePO4 olivine as electrode material for Li-ion aqueous rechargeable batteries

Since LiFePO4 batteries play a major role in the transition to safe, more affordable and sustainable energy production, numerous strategies have been applied to modify LFP cathode, with the aim of improving its electrochemistry. In this contribution, a highly vanadium-doped LiFe0.9V0.1PO4/C composite (LFP/C-10V) is synthesized using the glycine combustion method and characterized by x-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Thermogravimetry Differential Thermal Analysis (TGDTA) and Cyclic Voltammetry (CV). It is shown that 10wt.% of vanadium can substitute Fe positions, thus decreasing unit cell volume, which is followed by generation of Li3V2PO4 traces, as detected by CV. High vanadium doping does not change the carbon content in the composite (≈13 wt%) but improves its electronic conductivity and electrochemical performance in both aqueous and organic electrolytes. The reversibility and current response are increasing following the trend: LFP/C, LFP/C -3mol%V, LFP/C - 5 mol % and LFP/C-10 mol %. The best specific capacity is obtained for the most highly doped olivine, which exhibits a reversible process at 1 mV s−1 in an aqueous electrolyte, thus showing a peak-to-peak distance of 56 mV. The high capacity of LFPC-10V is measured in both LiNO3 and NaNO3 electrolytes amounting to around 100 mAh g−1 at 20 mV s−1. Still, the material is only stable in LiNO3 electrolyte, making it more suitable for Li than Na-ion aqueous rechargeable batteries.

Advanced Prussian Blue Cathodes for Rechargeable Li-Ion Batteries

Taking advantage of fact that the surface electrons of metallic nanoparticles (NPs) can be effectively released even at a low voltage bias, we demonstrate an improvement in the electrochemical performance of nanosized Prussian Blue (PB)-based secondary batteries through the incorporation of bare Ag or Ni NPs in the vicinity of the working PB NPs. It is found that the capacity for electrochemical energy storage of the 17 nm PB-based battery is significantly higher than the capacity of 10 nm PB-based, 35 nm PB-based or 46 nm PB-based batteries. There is a critical PB size for the highest electrochemical energy storage efficiency. The full specific capacity CF of the 17 nm PB-based battery stabilized to 62 mAh/g after 130 charge–discharge cycles at a working current of IW = 0.03 mA. The addition of 14 mass percent of Ag NPs in the vicinity of the PB NPs gave rise to a 32% increase in the stabilized CF. A 42% increase in the stabilized CF could be obtained with the addition of 14 mass percent of Ag NPs on the working electrode of the 35 nm PB-based battery. An enhancement in CF was also found for electrodes incorporating bare Ni NPs but the effect was smaller.

A Fast-Charge Graphite Anode with a Li-Ion-Conductive, Electron/Solvent-Repelling Interface.

Graphite has been serving as the key anode material of rechargeable Li-ion batteries, yet is difficultly charged within a quarter hour while maintaining stable electrochemistry. In addition to a defective edge structure that prevents fast Li-ion entry, the high-rate performance of graphite could be hampered by co-intercalation and parasitic reduction of solvent molecules at anode/electrolyte interface. Conventional surface modification by pitch-derived carbon barely isolates the solvent and electrons, and usually lead to inadequate rate capability to meet practical fast-charge requirements. Here we show that, by applying a MoOx-MoNx layer onto graphite surface, the interface allows fast Li-ion diffusion yet blocks solvent access and electron leakage. By regulating interfacial mass and charge transfer, the modified graphite anode delivers a reversible capacity of 340.3 mAh g-1 after 4000 cycles at 6 C, showing promises in building 10-min-rechargeable batteries with a long operation life.

Design, Testing, Evaluation, and Implementation of an Arduino-based Mosquito-Repellent System

Aims: The primary objective of this research drive is to design, develop, and evaluate an Arduino-based mosquito-repellent system. This work underscores the importance of developing sustainable and eco-friendly solutions for mosquito control.
 Study Design: An Arduino microcontroller board is used, and an assembly language program is developed to repel mosquitoes from the surroundings. This system uses piezoelectric disks, LED lights, LCD monitor along with the Arduino board and produces ultrasonic sound to protect humans and the environment from mosquitoes.
 Place and Duration of Study: The research effort was steered by the authors in a group under the supervisor of a faculty member as a part of the course capstone project work of the Bachelor of Science in Engineering degree in Computer Science and Engineering at the American International University Bangladesh (AIUB), Dhaka, Bangladesh. The authors performed their research tasks at AIUB from May 2023 to January 2024.
 Methodology: The innovative mosquito-repellent system uses an Arduino Mega 2560 microcontroller to generate a cutting-edge solution to tackle the problem of mosquito infestations. The system can produce an electric signal that can emit mechanical ultrasound signals to be harnessed using a series-connected eight piezo-electric discs. To power up the system, it uses four Li-ion rechargeable batteries charged by using solar energy from the home solar system. Besides, it uses LEDs to indicate the status of the repellent system.
 Results: The generated ultrasonic signal is observed on the oscilloscope screen and its’ value is exhibited on the LCD screen to evaluate the system performance. Testing confirms that the system can drive away mosquitoes within its 3 m surroundings in 2-3 minutes. Besides, the system parameter and cost comparison show that this scheme suggests a worthwhile and sustainable result for making a mosquito-free environment.
 Conclusion: The development of a mosquito-repellent system using ultrasonic sound waves based on an Arduino microcontroller offers a sustainable and effective alternative to traditional methods of mosquito control. Since the system is chemical and health-hazard-free, it is eco-friendly and makes human life more comfortable. The system is portable and cost-effective, making it suitable for use in various settings.

Recovery of isolated lithium through discharged state calendar ageing.

Rechargeable Li-metal batteries have the potential to more than double the specific energy of the state-of-the-art rechargeable Li-ion batteries, making Li-metal batteries a prime candidate for next-generation high-energy battery technology1-3. However, current Li-metal batteries suffer from fast cycle degradation compared with their Li-ion battery counterparts2,3, preventing their practical adoption. A main contributor to capacity degradation is the disconnection of Li from the electrochemical circuit, forming isolated Li4-8. Calendar ageing studies have shown that resting in the charged state promotes further reaction of active Li with the surrounding electrolyte9-12. Here we discover that calendar ageing in the discharged state improves capacity retention through isolated Li recovery, which is in contrast with the well-known phenomenon of capacity degradation observed during the charged state calendar ageing. Inactive capacity recovery is verified through observation of Coulombic efficiency greater than 100% on both Li||Cu half-cells and anode-free cells using a hybrid continuous-resting cycling protocol and with titration gas chromatography. An operando optical setup further confirms excess isolated Li reactivation as the predominant contributor to the increased capacity recovery. These insights into a previously unknown pathway for capacity recovery through discharged state resting emphasize the marked impact of cycling strategies on Li-metal battery performance.

N-doped lithium titanium oxide for high power Li-ion rechargeable batteries with excellent cyclability

Lithium titanate, Li4Ti5O12 (LTO) is being explored as an anode in Li-ion batteries owing to its minimal structural change during lithiation/delithiation and excellent capacity retention at higher current rates. However, the lack of stable cyclability at higher applied currents owing to low electronic conductivity, restricts its widespread applications. Solid state anionic doping represents a convenient strategy to improve the intrinsic electronic conductivity of the LTO material. Hence, a facile and scalable solid state‐inspired protocol has primarily been devised aimingthe large-scale production of nitrogen-doped LTO. The structural analysis demonstrates the diffusion of nitrogen into the lattice without damaging the intrinsic microstructure of LTO. The 2% nitrogen-doped LTO as a working electrode in Li-ion half-cell, displays enhancement in Li-storage capacity by 30%. Moreover, it exhibits excellent rate performance (131 mAhg−1 @ 5C) and ultra-long cycling stability upto 1000 cycles retaining 82 % capacity. Further, full cell study of N@LTO with LiCoO2 exhibits specific capacities of more than 155 mAh/g at a 0.05C rate. Overall, the enhancement in performance attributes to N doping which is likely to improve not only the electrical conductivity but also the ion transport capabilities. Hence the N@LTO will have potential in high power Li-ion batteries.

Challenges and opportunities using Ni-rich layered oxide cathodes in Li-ion rechargeable batteries: the case of nickel cobalt manganese oxides

Doping, coating, surface modification, formation of composites and control of crystalline orientation can control the capacity retention of Ni-rich cathodes. Furthermore, the design of Co-free Ni-rich cathodes may provide a cost-effective solution.

Investigating the Reaction Mechanism of Vinylene Carbonate Additive in Lithium Ion Batteries Using X-Ray Photoelectron Spectroscopy

The rechargeable Li-ion battery is an enabling technology which facilitates the electrification of the automotive industry and reduces the demand for fossil fuels. During the charge and discharge of a battery, a solid-electrolyte interphase (SEI) forms between the liquid electrolyte and the solid negative electrode as a result of electrolyte degradation. The chemical and physical stability and the functionality of the SEI is a key determining factor of battery performance. The chemical composition of the SEI is mainly controlled by the choice of solvent and salt used, but can be manipulated by the addition of electrolyte additives that influence the electrolyte degradation process.Vinylene carbonate (VC) is an additive used in many commercial Li-ion battery configurations. The addition of a small amount of VC to ethylene carbonate (EC) containing electrolytes has been demonstrated to drastically improve several performance metrics for batteries including cycle life, coulombic efficiencies, capacity retention and thermal stability. The success of VC is widely attributed to its ability to form a thinner, denser and more robust SEI, which better protects the electrode surface and prevents further electrolyte consumption. This improvement in stability has been linked to the presence of poly(VC) in the SEI, but the mechanism by which VC reacts in EC-containing electrolytes is still an area of ongoing study. Whilst computational methods have suggested several potential decomposition pathways of electrolytes containing VC, it is yet to be convincingly demonstrated experimentally. Whilst there is a general consensus about ‘What?’ forms in the SEI on the addition of VC to EC-containing solvent, this work aims to confirm ‘Where?’ these components are in the interface and the currently unanswered questions of ‘How?’ and ‘Why?’ they form.Using highly surface sensitive photoelectron spectroscopy (PES) measurements of the SEI deposited at various potentials, we identify the differences in composition and structure that result from the addition of VC additive to EC-containing electrolytes. The SEI formation is studied using a smooth Au surface as the model working electrode and a fluorine free EC:diethyl carbonate (DEC) (1:9) 1 M LiClO4 electrolyte in an attempt to isolate the impact of VC on the SEI. A potential step procedure allows analysis of the working electrode surface by PES at several progressively more negative potentials on the first charge. Through systematic variation of components such as the concentration of VC, the ratio of EC:DEC and swapping Au for other electrode materials such as Cu or Si, the interaction between VC, EC and the electrode surface is revealed. The differences in SEI composition and structure formed in each environment and at each potential step are correlated to quartz crystal microbalance (QCM) data in order to identify potential reaction mechanisms and formation processes. The results play a key role in understanding the reaction pathway of VC-containing electrolytes and will accelerate development of more efficient electrolyte additives.

Bio-Waste Derived Hard Carbon: Effect of Treatment Conditions on Electrochemical Performance

There is a great deal of demand for rechargeable Li-ion batteries due to their high energy and power density compared to other rechargeable batteries. Despite the concern about limited lithium resources, scientists have re-examined sodium-ion batteries, since sodium is below lithium on the periodic table, and the two metals have many similar properties. As a result of its low cost, good cycle life, and reversible capacity, hard carbon (HC) is considered to be the most attractive negative electrode material for sodium-ion batteries. Nevertheless, the practical application of HC remains challenging due to its low capacity and initial Coulombic efficiency (ICE). We investigated how pre-treatment conditions affected the graphitization degree in order to overcome these issues. In addition, we observed a strong correlation between pre-oxidation and electrochemical performance when the carbonization temperature was increased. The observed results will be presented during the presentation. Acknowledgments This work was funded by the Ministry of Education and Science of the Republic of Kazakhstan Grant (AP09259165) and by Nazarbayev University under Collaborative Research Program Grant № 20122022P1611, AK.

Structural, electrical, and electrochemical studies of the olivine LiMPO4 (M=Fe, Co, Cr, Mn, V) as cathode materials for lithium-ion rechargeable batteries based on the intercalation principle

Despite significant efforts to identify other substituents, carbon remains the only economically viable negative electrode (anode) material for Li-ion batteries (LIBs). The current state of knowledge on the understanding, characterization, and improvement of carbon anode materials is reviewed. A brief history of developments in carbon host lattices is provided. The methodologies used to characterize the lithium insertion and de-insertion processes and a wide spectrum of carbon materials, from amorphous to highly oriented graphitic materials, are described. The basic studies of the electrochemical process on natural graphite and highly oriented pyrolitic graphite materials are then thoroughly examined. Following that, the issues and opportunities of several hard carbon compounds that boost battery capacity are examined. Several innovative carbon materials and carbon-based composites are also introduced. The electrochemical interaction of anode material with lithium could produce an intercalation product, which serves as the foundation for a novel battery system. Structural retention causes this reaction to proceed quickly and with a high degree of reversibility at room temperature. Titanium disulfide is one of the latest solid cathode materials. In this context, the paper presents a comprehensive theoretical comparison of the electrochemical electrical and physical properties of iron (Fe)-, cobalt (Co)-, manganese (Mn)-, chromium (Cr)-, and vanadium (V)-based LiMPO4 materials for cathode design in lithium (Li)-ion battery applications using the intercalation principle. The work highlighted many material and performance aspects of the cathode design, such as the cohesive energy of the material, Li-intercalation energy in olivine structure, and physical, electrochemical, and electrical analyses of LiMPO4 for rechargeable Li-ion batteries. We also examine the evolution of LIB technology based on the olive cathode materials, which are also evaluated.

Printable and Free-Standing Silicon-Based Anode for Current Collector-Free Lithium-Ion Batteries.

The evolution of Li-ion rechargeable batteries has driven a demand for systems exceeding the energy density and shape diversity of conventional lithium-ion batteries. Silicon (Si)-based materials, suitable for high-energy-density applications, have been restricted in practical use due to their inherent structural instability and poor conductivities upon electrochemical cycling. Here, we propose a fully printable and free-standing anode, composed of hollow SiOx/C (H-SiOx/C) composite material and an MXene conductive binder, exhibiting high specific capacity, structural reliability, and superior ionic conductivity without any current collector. The hollow structure of H-SiOx/C accommodates volume changes during cycling, while the MXene binder forms a three-dimensional interconnected conducting structure for maintaining the structural integrity of electrodes without a current collector. Furthermore, the printability and free-standing nature of the H-SiOx/C/MXene anode are validated in both coin-type full cell and heart-shaped pouch cell configurations through a straightforward stencil printing technique. This work establishes a foundation for advanced Si-based anodes, enhancing performance and design flexibility and potentially contributing to practical printable battery systems.

Synthesis of 1D/2D VO2 (B) nanowire/g-C3N4 hybrid architectures as cathode materials for high-performance Li-ion batteries

Owing to energy density, powder density, and eco-friendliness, Li-ion batteries (LIBs) are increasingly used in transportable electronic devices and electric vehicles. Monoclinic VO2 (B) has been broadly used as a cathode owing to its abundance, affordability, high capacity, and multiple oxidation states, but it's low repeatability and slow kinetics have restricted its practical applications. To mitigate these shortcomings, novel 1D/2D VO2 (B) nanowire/g-C3N4 hybrid architecture cathode materials were synthesized via hydrothermal method, and its electrochemical activity (i.e., repeatability constancy and rate capability) for LIBs was investigated. X-ray diffraction experiments confirmed that VO2 (B) exhibited a monoclinic crystal phase. SEM images revealed that the g-C3N4 and VO2 (B) presented sheet-like morphologies and comprised nanowires of uniform thickness, respectively. Electrochemical experiments revealed that the hybrid architectures showed a capacity of 779 mAh/g, and VO2 (601.4 mAh/g) and g-C3N4 (340.6 mAh/g) at 0.1 C current density. The remarkable electrochemical activity of the materials was attributed to their distinctive structures, excellent electronic conductivity associated with g-C3N4 sheets, small transport distances for Li+ ions, and fast charge transmission owing to the presence of VO2 (B) nanowires attached to g-C3N4 sheets. Consequently, distinct VO2 (B) nanowire/g-C3N4 hybrid architectures delivered suitable electrode performance to facilitate the design of high-power LIBs and these hybrid composites can serve as suitable cathode materials for rechargeable LIBs.

Boosting interfacial kinetics in extremely fast rechargeable Li-ion batteries with linear carbonate-based, LiPF6-concentrated electrolyte

Amidst the surging demand for battery-powered automobiles, it is crucial to tackle the safety risks of Li plating triggered by high cell polarization to achieve extremely fast charging (XFC) of Li-ion batteries. This study explores the impact of Li+ desolvation and solid-electrolyte interphase (SEI) chemistry on cell polarizations by utilizing linear carbonate (LC)-based, LiPF6-concentrated electrolytes (LPCEs). In the LC family, dimethyl carbonate (DMC) is thermodynamically preferred to facilitate desolvation kinetics, thereby lowering the charge-transfer barrier at the graphite anode. For effective graphite passivation and faster Li+ diffusion crossing the SEI, fluoroethylene carbonate (FEC) can help build up a thin and fluorinated SEI and reinforce the XFC cycling stability of graphite||NMC622 full cells (3.0 mAh cm−2; N/P ratio = 1.1), exhibiting 94.3% capacity retention over 500 cycles under a 10-min charging condition. The excellent XFC performance is practically validated using a 1.2-Ah pouch cell, demonstrating three times higher capacity retention over 200 cycles while suppressing Li plating-triggered cell swelling compared to conventional electrolytes. Unraveling the cell polarization governed by electrolyte chemistry provides valuable insights regarding future electrolyte designs for improving the XFC capabilities of Li-ion batteries.

Two-dimensional Ni-MOF as a high performance anode material for lithium ion batteries

Metal organic frameworks (MOFs) have attracted extensive attention as electrode materials for use in Li-ion batteries owing to their diverse structural chemistry. Herein, a new type of two-dimensional (2D) Ni-MOF is presented as a high-performance anode material for rechargeable Li-ion batteries. The layered structure endows the Ni-MOF with free channels between the inter-layers, which is beneficial to Li+ ion diffusion, making it stand out from a crowd of porous 3D molecular materials. Strikingly, when tested at 100 mA g−1, Ni-MOF demonstrates a high capacity of 765 mA h g−1. The anode material also delivers superior rate performance and good cyclability. After being charged/discharged to high rates of 2 A/g, the anode could restore its initial capability at 100 mA g−1.

Studying the Role of Additives in Carbonate Electrolytes for Graphite||NMC811 Batteries with Interface-Sensitive X-Ray Spectroscopies

Li-ion rechargeable batteries are increasingly used as power sources for portable consumer products and electric vehicles. The formation of stable electrode-electrolyte interphases is critical to long-term performance, however, these typically degrade during extended cycling due to ongoing side reactions and electrode cross-talk. Over the past few years, various electrolyte additives have been reported as being able to improve the properties of the interphases formed on electrode surfaces and suppress cell degradation. However, these are often tuned for a specific electrode (e.g. cathode), and may negatively impact on the other electrode (e.g. anode). A key experimental challenge is therefore to reveal how additives affect the interfacial layers formed at both anode and cathode in full cells, their resulting influence on the cross-talk, and on the long-term stability of each electrode. Soft X-ray absorption spectroscopy (soft-XAS) and X-ray photoelectron spectroscopy (XPS) are powerful techniques to investigate the evolution of the short-range local structure and chemical species in complex systems. These properties make soft-XAS and XPS a suitable technique to study phase evolution, chemical species, local structure and stability of the interface formed on the electrodes. Here, we have studied carbonate-based electrolytes with various additives (such as Vinylene Carbonate, Lithium difluorophosphate, and fluoroethylene carbonate) in Graphite||NMC811 full cell. Soft-XAS and XPS have been performed to understand how additives in the electrolyte alter the chemical nature of interface formed on both anode and cathode in early cycles and their influence on extended longer-term degradation related to cross-talk, such as transition metal cross-over. Further, we identified which additives are beneficial for which electrodes and which cross-talk reactions they help to mitigate, this informs the development of electrolyte formulations where different additives are combined to improve battery lifetime and performance. Comparing the chemical information obtained with electrochemical cycling data we determined the connection between the chemical degradation of the electrodes and the reduction in electrochemical performance.

Simple and Scalable Synthesis Method of γ-NaTiOPO4 for Sodium Ion Batteries in Aqueous and Non-Aqueous Electrolytes

Lithium-ion batteries have been considered a suitable battery technology for energy storage systems. However, its scarcity and high cost pose challenges to the availability of lithium for mass adoption in large applications such as energy storage. Due to their natural abundance and economic feasibility, sodium-ion batteries (SIBs) have proven to be a promising alternative for large-scale applications.1 Most anode materials for research on SIBs have focused on carbonaceous materials, oxides and polyanionic compounds of the anode, like that of lithium-ion battery research on anode materials Polyanionic compounds, especially phosphates, are of particular interest due to their structural, thermal properties and, more importantly, for avoiding undesirable sodium plating.2 Contrary to lithium counterparts, SIBs have fewer alternatives for safe anode materials applicable for both non-aqueous and aqueous rechargeable SIBs.3 Various NaTiOPO4 polymorphs have previously been reported, and these materials required a synthesis process that was extremely time-consuming and a highly pressured synthesis atmosphere. However, the methods reported still produced very small amounts of synthesized material.4-8 Due to these limitations, only the β-NaTiOPO4 phase among polymorphs was studied as an anode for SIBs in a non-aqueous electrolyte.7-8 In this study, we first report a simple and scalable solid-state synthesis method for γ-NaTiOPO4, which incorporates a high-temperature quenching process to stabilize metastable γ-NaTiOPO4 with stability. It is a promising anode for SIBs in non-aqueous and aqueous electrolytes, with a capacity of roughly 120mAh/g, voltages of 1.7V and 1.5V vs Na/Na +, and a Coulombic efficiency of up to 99.9% for up to 500 cycles at 0.5C in non-aqueous electrolyte and excellent capacity retention in a full cell of NaMn0.44O2//γ-NaTiOPO4 for up to 175 cycles in aqueous electrolyte.9 El Kharbachi, A.; Zavorotynska, O.; Latroche, M.; Cuevas, F.; Yartys, V.; Fichtner, M., Exploits, advances and challenges benefiting beyond Li-ion battery technologies. Journal of Alloys and Compounds 2020, 817.N. Yabuuchi, K. Kubota, M. Dahbi, S. Komaba, Research development on sodium-ion batteries, Chem. Rev. 114 (23) (2014) 11636–11682. H. Kim, J. Hong, K.Y. Park, H. Kim, S.W. Kim, K. Kang, Aqueous rechargeable Li and Na ion batteries, Chem. Rev. 114 (23) (2014) 11788–11827. Stus, N. V.; Slobodyanik, M. S.; Straitiychuk, D. A.; Lisnyak, V. V., Pressure induced gamma ->alpha-NaTiOPO4 phase transition. J Alloy Compd 2005, 393 (1-2), 66-69.Dahaoui, S.; Hansen, N. K.; Protas, J.; Krane, H.-G.; Fischer, K.; Marnier, G., Electric properties of KTiOPO4 and NaTiOPO4 from temperature-dependent X-ray diffraction. Journal of Applied Crystallography 1999, 32 (1), 1-10.Loiacono, G. M.; Loiacono, D. N.; Stolzenberger, R. A., Growth and properties of crystals in the system KTiOPO4-NaTiOPO4. Journal of Crystal Growth 1994, 144 (3), 223-228.Mu, L. Q.; Ben, L. B.; Hu, Y. S.; Li, H.; Chen, L. Q.; Huang, X. J., Novel 1.5 V anode materials, ATiOPO(4) (A = NH4, K, Na), for room -temperature sodium-ion batteries. Journal Jiang, L. W.; Liu, L. L.; Yue, J. M.; Zhang, Q. Q.; Zhou, A. X.; Borodin, O.; Suo, L. M.; Li, H.; Chen, L. Q.; Xu, K.; Hu, Y. S., High-Voltage Aqueous Na-Ion Battery Enabled by Inert-Cation-Assisted Water-in-Salt Electrolyte. Advanced Materials 2020, 32 (2).Kim, D.; Park, H.; Avdeev, M. ; Kim, M. ; Kang, B. (2022). Newly developed γ – NaTiOPO4 by Simple Solid-State Synthesis for Anode Material of Na-ion Batteries in Both Non-aqueous and Aqueous electrolyte. Journal of Power Sources 2022, 541 (1)