Cycles For Lithium-ion Batteries Research Articles

A life-prediction method for lithium-ion batteries based on a fusion model and an attention mechanism

The current life-prediction models for lithium-ion batteries have several problems, such as the construction of complex feature structures, a high number of feature dimensions, and inaccurate prediction results. To overcome these problems, this paper proposes a deep-learning model combining an autoencoder network and a long short-term memory network. First, this model applies the characteristics of the autoencoder to reduce the dimensionality of the high-dimensional features extracted from the battery data set and realize the fusion of complex time-domain features, which overcomes the problems of redundant model information and low computational efficiency. This model then uses a long short-term memory network that is sensitive to time-series data to solve the long-path dependence problem in the prediction of battery life. Lastly, the attention mechanism is used to give greater weight to features that have a greater impact on the target value, which enhances the learning effect of the model on the long input sequence. To verify the efficacy of the proposed model, this paper uses NASA’s lithium-ion battery cycle life data set.

Titanium Monoxide-Stabilized Silicon Nanoparticles with a Litchi-like Structure as an Advanced Anode for Li-ion Batteries

Silicon (Si) has been considered as the most potential anode material for next-generation high-energy density lithium-ion batteries (LIBs) because of its extremely high theoretical capacity. However, the performance deterioration caused by volume change and low electrical conductivity of active Si particles greatly limit its commercial use. Here, we designed a nonstoichiometric TiOx-coated Si anode with a litchi-like structure, in which Si-Ti and Si-O dual bonds are expected to form between the Si core and TiOx shell. This unique structure plays a major role in preventing the volume expansion and improving the electrical conductivity of the Si anode. The as-prepared TiOx-coated Si anode could exhibit excellent cycling stability after 1000 cycles at 1000 mA g-1 with a relatively small capacity decay rate of ∼0.04% per cycle, which can be comparable to most of the modified Si anodes in references. This strategy of surface regulating on the Si anode could be extended to other electrodes with large volume expansion during cycling in LIBs for achieving competitive electrochemical properties.

Spherical-graphite/nano-Mn2O3 composites as advanced anode materials for lithium half/full batteries

The spherical-graphite/Mn2O3 composites (SG/Mn2O3) with a core-shell structure have been facilely synthesized by the initial coprecipitation method and subsequent calcination treatment. As-synthesized composites as anode materials demonstrate remarkable lithium storage performances. The optimal SG/Mn2O3 with 17.6 wt% of Mn2O3 nanoparticles manifests the charge capacity of 499 mA h g−1 over 100 cycles at 0.5 A g−1, and presents the reversible capacity of 383 mA h g−1 under 2 A g−1 after 1000 long cycles for lithium-ion half batteries. When the optimal SG/Mn2O3 electrode is assembled to full-cell using LiFePO4 as the cathode, the full-cell affords the discharge capacity of 318 mA h g−1 with capacity retention of 97.2% at 0.1 A g−1 over 30 cycles. The high capacity of Mn2O3 nanoparticles coating on the surface/interface of SG enhances the long-periodic cycling properties and rate performance of overall electrode. The superior lithium storage performance demonstrates that the SG/Mn2O3 has great potential in the new-generation energy storage devices.

Facile and solvothermal synthesis of rationally designed mesoporous NiCoSe2 nanostructure and its improved lithium and sodium storage properties

Rechargeable metal ion batteries have attracted considerable attention in modern society because environmental issues are getting worse over time. They are highly expecting to play a vital role in day-to-day life in portable electronic devices (EVs) as well as hybrid electric vehicles (HEVs). Herein, we report the synthesis of bimetallic dichalcogenide by a solvothermal technique and systematically explore the effect of mesoporous NiCoSe2 (MNCS) nanostructures by controlling the ratio of surface-active agent during the synthesis process. The depth morphological evaluation using high-resolution field-emission transmission electron microscopy (HR FE-TEM) suggests that all the MNCS nanostructures display similar morphology with an extended network of material architecture when the ratio of surface active agent increased and thus interestingly play an important role in enhancement of surface area and porosity of the as-prepared electrode architecture. Interestingly, an obtained MNCS50 nanostructure displays a specific capacity of 557 and 398 mAh g−1 after 100 and 60 cycles for lithium ion batteries (LIBs) and sodium ion batteries (SIBs), respectively. The larger surface area and high porous nature of MNCS50 nanostructure affords more spaces to accommodate larger numbers of lithium (Li) and sodium (Na) ions during the discharge/charge process, and the nanostructured electrode material often enhances the electrical conductivity. These observations are indicating the use of nanostructured anode materials for LIBs and SIBs.

Impact of ionic liquid on lithium ion battery with a solid poly(ionic liquid) pentablock terpolymer as electrolyte and separator

In this study, the physical, transport, mechanical, morphological, and electrochemical properties of a ternary blend solid polymer electrolyte (SPE) (poly(ionic liquid) (PIL) multiblock polymer, lithium salt, and ionic liquid (IL)) were systematically investigated as a function of IL concentration. With increasing IL concentration, the conductive volume increases along with the polymer chain segmental mobility. This facilitates high ionic conductivity, while the mechanical modulus exhibits a percolation threshold. Surprisingly, at higher IL concentrations, there is a reduction in the lithium cation mobility as evidenced by pulsed-field gradient nuclear magnetic resonance, which coincides with an increased overpotential evidenced by lithium metal stripping and plating. Stable lithium ion battery cycling durability (over 100 cycles at room temperature) is demonstrated with the ternary blend SPE as the electrolyte and separator. This work provides valuable insights into the design of new SPEs with both high ionic conductivity and improved battery stability.

Cross-linked K2Ti4O9 nanoribbon arrays with superior rate capability and cyclability for lithium-ion batteries

Cross-linked K2Ti4O9 nanoribbon arrays (KTO-NRAs) have been synthesized and firstly utilized as additive-free anodes for lithium-ion batteries (LIBs). The cross-linked nanoribbon array configuration endows the KTO-NRAs with excellent structural stability and directional ion and electron transport pathways. Meanwhile, the layer structure of K2Ti4O9 nanoribbons offers a large interlayer spacing of 0.91 nm for fast lithium ions insertion/extraction. Consequently, the KTO-NRAs electrode exhibits high reversible capacity (241.5 mAh g−1 at 0.2 A g−1) and superior rate capability (105.9 mAh g−1 at 5.0 A g−1), as well as impressive cyclability (85.5% capacity retention efficiency over 3000 continuous cycles at 2.0 A g−1), holding a good prospect of application in high-performance LIBs.

Doping of titania with manganese for improving cycling and rate performances in lithium-ion batteries

Titanium dioxide have received a much attention for lithium-ion batteries due to safety as anode upon fast and low temperature cycling as well as appropriate stability during insertion and extraction of guest ions. However, TiO2 has low conductivity and sluggish diffusion of Li+. In order to eliminate these shortcomings, reducing of particle size and doping are considered as promising approaches. Herein, we investigate the effect of doping with manganese (atomic ratios of Mn/Ti = 0.05; 0.1; 0.2) on characteristics of anatase titania having nanoparticulate morphology. As found, Mn/Ti = 0.05 is optimal dopant concentration in terms of battery performance of titania: the capacity of 113 mAhg−1 was still maintained after 118 cycles at 1C that is rather higher as compared to undoped anatase. Such improved electrochemical behavior is associated with anatase lattice expansion due to Mn3+ incorporation and enhanced conductivity.

Preparation of CuO@PPy hybrid nanomaterials as high cyclic stability anode of lithium‐ion battery

Over the recent 20 years, numerous researches have focused on the lithium-ion batteries anodes of MOx 3d-metal oxides which have a high specific capacity. For example, the specific capacity of CuO material as an anode is ∼670 mAh g−1. Unfortunately, serious capacity degradation limits their promising applicability. To improve cyclic stability, PPy is covered on CuO surface to prepare CuO@PPy core–shell hybrid materials by chemical polymerisation. Pyrrole amount plays an important role on control the PPy shell thickness. After PPy coating, the lithium-ion battery cycling stability and coulombic efficiency have been improved greatly, and CP-5 sample has the best cyclic stability and coulombic efficiency. The capacity retention of bare CuO is only 27.9% after 200 cycles. By contrast, the capacity retention of CP-5 sample is ∼100%. The flexible conducting polymers shell (PPy) lead to improved cyclic stability. These results give a strategy to solve MOx 3d-metal oxide capacity degradation as Lithium-ion batteries anode.

Unique amorphous manganese oxide/rGo anodes for lithium-ion batteries with high capacity and excellent stability

The utilization of manganese oxide anode materials in lithium-ion batteries is hindered by low conductivity, high stress/strain, volume expansion, and high over potential in the crystalline structure during cycling. Compared with crystal oxide, amorphous oxide has attracted attention for its weak chemical bond force and its low stress change during the phase change process, but few reported in lithium-ion batteries. This work combined both advantages of amorphous manganese oxide (AMO) and reduced graphene oxide (rGo) to produce a unique AMO/rGo composite electrode material through one-step chemical reduction the KMnO4 in graphene oxide containing solution. The rGo-supported porous amorphous structure of manganese oxide brought special character by reducing the stress/strain of the conversion reaction, thus ensuring a high capacity and high stability. The high electronic and lithium-ion conductivity of graphene also enhanced the rate capability. As a result, the as-synthesized AMO/rGo exhibited a large reversible specific capacity (784 mA hg−1 at the current density of 1 A g−1 over 500 cycles) and superior rate capability, making it a potential candidate as high-performance electrode material for long-term cycling in lithium-ion batteries.

High accuracy in-situ direct gas analysis of Li-ion batteries

Cycling of lithium-ion batteries containing Ni-rich NMC cathodes at high voltage involves intense gas generation. From a safety standpoint, it is critical to understand how different gas species respond to changes in upper cut-off voltages. In this manuscript, we introduce a novel experimental set up for real-time analysis of gas generation in prismatic pouch cells. In a typical experiment, a lithium-ion pouch cell is directly connected to a quadruple mass spectrometer using a glass capillary. Pressure difference helps move the generated gases to the mass spectrometer column for full analysis. The gaseous species are probed during both formation cycle and aging cycles in Li-ion pouch cells comprising NMC811 cathodes and graphite anodes. The gases are generated upon the creation of the solid electrolyte interphase on graphite during the first formation charge. Ethylene (C2H4) is the major gas generated during formation cycle due to the decomposition of ethylene carbonate. H2, CH4, C2H6, O2, CO and CO2 are also monitored during formation cycle. For the aging cycles, three upper cut-off voltages 4.2, 4.4 and 4.6 V are selected to investigate the impact of upper cut-off voltages on gas generation. Higher upper cut-off voltages do not significantly affect the amount of O2 measured, as a part of the generated oxygen could have reacted with electrolytes. On the other hand, the generation of CO2 is found to be very sensitive to upper cut-off voltage. During similar aging cycles, 6167 nmol gNMC−1 of CO2 is generated in 4.6 V cycle, versus 1650 nmol gNMC−1 in 4.4 V cycle, versus 91 nmol gNMC−1 in 4.2 V cycle.

Correction to Unveiling the Role of Al2O3 in Preventing Surface Reconstruction During High-Voltage Cycling of Lithium-Ion Batteries

Correction to Unveiling the Role of Al₂O₃ in Preventing Surface Reconstruction During High-Voltage Cycling of Lithium-Ion Batteries

(Invited) Kerr Gated Raman Spectroscopy to Investigate Aging Processes on Lithium-Ion Electrode Interfaces

Aging mechanisms have a great impact into batteries calendar life and performance. A better understanding of these complex processes is critical to improve the lifetime of the battery. Electrolyte aging plays a key role in the decrease of capacity since insoluble species and gas by-products are formed during the electrochemical cycling of the battery. Fluorescent species are formed during cycling of lithium ion batteries as a result of electrolyte decomposition due to the instability of the non-aqueous electrolytes and side reactions that occur at the electrode surface. The increase in the background fluorescence due to the presence of these components makes it harder to analyze data due to the spectroscopic overlap of Raman scattering and fluorescence. Herein we will demonstrate Kerr gated Raman spectroscopy as an effective technique for the isolation of the scattering effect from the fluorescence enabling the collection of the Raman spectra of LiPF6 salt and LiPF6-based organic carbonate electrolyte, without the interference of the fluorescence component. A comparison will be made with FT-Raman using a Laser excitation at 1064 nm, where we show that it is possible to obtain Raman spectra of Li-ion battery relevant materials above a diminished fluorescence background, but with a much lower sensitivity compared to using Kerr Gated Raman with an excitation at 400 nm. Kerr gated Raman was able to identify POF3 on the LiPF6 particle surface [1], after the addition of trace water and the degradation of graphitic carbon electrodes with respect to number of cycles.[1] L. Cabo-Fernandez, A.R. Neale, F. Braga, I.V. Sazanovich, R. Kostecki, L.J. Hardwick, Phys. Chem. Chem. Phys . , 2019,21, 23833-23842 Figure 1

Approaches to Better Determination of Oxidative Stability of Solid-State Electrolytes

The undesirable reaction between electrolyte and cathode material at a high state of charge (SOC), i.e. the oxidative decomposition of electrolyte, results in electrolyte consumption, capacity fading and eventual battery failure during prolonged cycling of lithium-ion batteries (LIBs). The problem is becoming more pronounced as research turns to all-solid-state lithium-ion batteries (SSLIB). In conventional LIBs employing liquid electrolyte, the species oxidized at the cathode surface can diffuse back into the bulk liquid; thus, the effective oxidized species concentration near cathode surface is low. However, due to the chemical nature and slow solid-state diffusivity, oxidized species can accumulate around the cathode-solid electrolyte interface, forming a resistive layer. In this sense, the issue of oxidative decomposition of solid electrolyte is intrinsically worse than liquid electrolyte. The pursuit of novel cathode compositions with even higher delithiation potentials and higher nickel content further exacerbates the problem, greatly increases the decomposition rate of the solid electrolyte. A thorough understanding of the oxidative decomposition behavior of solid-state electrolytes is needed. However, the most commonly used method for determining the oxidative stability of solid-state materials, linear scanned voltammetry (LSV), is predominantly a kinetic method. Onset potential generated by this method not only lacks thermodynamic significance but also varies greatly due to test cell configurations and sample preparation techniques. For example, independent research groups have reported oxidation potentials for PEO electrolytes spanning from 4-5.5V vs. Li/Li+. In practice, PEO based electrolytes are often found decomposing on cathode surfaces with charge potentials above 4V.This work focuses on establishing a more accurate estimation of the stability threshold of solid-state materials within a reasonable time. In practical SSLIB systems, the solid-state electrolyte is in contact with a considerable amount of cathode particle and conductive additives, providing a large number of possible sites for decomposition. Thus, in a more accurate measurement, large amount of conductive carbon was blended with the tested material to increase the active working electrode area. Comparing to LSV which usually carried on a polished inert surface, the new method provides a more similar scenario to SSLIB. Furthermore, in common LSV practices, the oxidation limit is usually determined by setting an onset current density. However, the current density of a particular test is strongly affected by both the conductivity/kinetics of the tested material and cell configuration. The arbitrariness of cell preparation and difference between materials made LSV a flawed method for comparing stability between different materials, yet a comparison of decomposition threshold between materials is widely seen among references. To resolve this issue, a dimensionless number R, or irreversibility factor was introduced into the analysis. R is defined as the ratio between irreversible capacity and reversible capacity. Experimentally, the carbon-infused material was scanned between OCV and a cutoff potential using cyclic voltammetry, and R is calculated from the charge passed through the cell. Using this new method, two polymer electrolytes, poly(ethylene oxide) (PEO) and hydrogenated poly(butadiene-co-acrylonitrile) (HNBR) combined with lithium bis(trifluoromethane sulfonyl)imide (LiTFSI) have been characterized. Their stability was found 3.8V vs. Li/Li+ for PEO and 4.3V vs. Li/Li+ for HNBR. The values determined by the new method were found in good agreement with battery tests.

Electrophoretic deposition of antimony/reduced graphite oxide hybrid nanostructure: A stable anode for lithium-ion batteries

Rechargeable batteries are ubiquitous in today’s world and find numerous applications starting from electronic gadgets to electric vehicles owing to their high energy density and battery life. Antimony (Sb) is considered a promising alternative anode to graphite, offering excellent theoretical capacity (660 mAh g−1) for the development of high energy density lithium-ion batteries (LIBs). However, Sb suffers from rapid capacity fade during galvanostatic cycling in LIBs owing to intrinsic volumetric strain (∼135%). Here, we demonstrate poly(acrylic acid) and nickel nitrate assisted electrophoretic deposition (EPD) of Sb/RGO anode on the copper foil is a viable option for electrode preparation over traditional doctor blade tape casting route. The EPD-Sb/RGO anode offers a stable discharge and charge capacity of ∼498.1 mAh g−1 and ∼497.8 mAh g−1, respectively, up to 100 cycles at a high current rate of 0.5 A g−1. Microstructural analysis shows that Sb and RGO deposited uniformly on copper foil and develop a sandwich-like structure of Sb nanoparticles interspersed in-between RGO planes. It is demonstrated that poly(acrylic acid) and nickel nitrate assisted sterically stabilized Sb/RGO composite mass remains intact on Cu foil post 100 cycles for EPD-Sb/RGO electrode may be the reason for stable capacity, conspicuously absent for electrode prepared by tape casting route.

Enhancing High-Temperature and High-Voltage Performances of Single-Crystal LiNi0.5Co0.2Mn0.3O2 Cathodes through a LiBO2/LiAlO2 Dual-Modification Strategy

The limited lithium ion diffusion and depressed cathode/electrolyte interface stability greatly deteriorate the cycling and rate performance of lithium ion batteries, especially when they are opera...

SEI Growth Impacts of Lamination, Formation and Cycling in Lithium Ion Batteries

The accumulation of solid electrolyte interphases (SEI) in graphite anodes related to elevated formation rates (0.1C, 1C and 2C), cycling rates (1C and 2C), and electrode-separator lamination is investigated. As shown previously, the lamination technique is beneficial for the capacity aging in graphite-LiNi1/3Mn1/3Co1/3O2 cells. Here, surface resistance growth phenomena are quantified using electrochemical impedance spectroscopy (EIS). The graphite anodes were extracted from the graphite NMC cells in their fully discharged state and irreversible accumulations of lithium in the SEI are revealed using neutron depth profiling (NDP). In this post-mortem study, NDP reveals uniform lithium accumulations as a function of depth with lithium situated at the surface of the graphite particles thus forming the SEI. The SEI was found to grow logarithmically with cycle number starting with the main formation in the initial cycles. Furthermore, the EIS measurements indicate that benefits from lamination arise from surface resistance growth phenomena aside from SEI growth in superior anode fractions.

Discovery of an Unexpected Metal Dissolution of Thin‐Coated Cathode Particles and Its Theoretical Explanation

AbstractThe degree of metal dissolution of cathode materials is a critical parameter in determining the performance of lithium‐ion batteries (LIBs). Ultra‐thin coated cathode particles, fabricated via atomic layer deposition (ALD), exhibit superior battery performance over that of bare particles. Therefore, it is generally believed that a coating layer protects the particles from metal dissolution of active materials, which is a critical cathode degradation mechanism. However, it is observed that ultra‐thin CeO2 coating intensified the Mn dissolution of LiMn2O4 (LMO) during cycling of LIBs, whereas ultra‐thin Al2O3 coating tended to inhibit Mn dissolution. A detailed density functional theory (DFT) study is carried out to explain these experimental observations by analyzing interaction of Mn atoms with neighboring electrode atoms in terms of energetic and structural aspect. All atomic and electronic analyses are consistent with the experimental observations. Several common materials are investigated as possible ALD coatings for LIBs to provide general insight, and it is found that Mn dissolution can be suppressed or accelerated depending on the material selection. This is the first report finding that depending on the coating material, metal dissolution can be accelerated, providing new insights into the impact of ALD coating materials on metal dissolution in cathode materials.

Lithium-Gold Reference Electrode for Potential Stability During In Situ Electron Microscopy Studies of Lithium-Ion Batteries

Electrochemical liquid-phase transmission electron microscopy (TEM) is showing excellent promise in fundamental studies of energy-related processes including lithium-ion battery (LIB) cycling. A key requirement to accurately interpret the measurements and acquire quantitative information is the implementation of a reliable reference electrode. Quasi-reference electrodes (QRE) remain commonly used due to microfabrication constraints of the electrochemical cell, however, they typically yield dramatic potential drifts making the electrochemical results inconclusive. Here, we present a method of producing a stable and readily interpretable lithium-gold alloy micro-reference electrode, which exhibits a reference potential of 0.1 V vs Li/Li+. We first examine the feasibility of electrochemically alloying a pristine gold electrode, patterned on a chip for in situ TEM, using a benchtop setup, and investigate various sources to support the lithiation. We confirm the presence of the Li-Au alloy using chronopotentiometry (CP) and open circuit voltage (OCV) measurements, and by scanning electron microscopy (SEM), electron energy loss spectroscopy (EELS) and high-resolution (HR) TEM. Finally, we apply this methodology in situ and use LiFePO4 as a model cathode material to demonstrate the merit of the Li-Au alloy reference electrode for obtaining reproducible cyclic voltammetry (CV) measurements on a liquid cell microelectrode system.

Facile synthesis of CTAB assisted hierarchical-structure TiO2@SnO2 for lithium storage

Tin oxide (SnO2) with high specific capacity and excellent safety performance has become potential candidate for next generation lithium-ion batteries (LIBs). However, the practical application of SnO2 is hindered by large volume change and particle aggregation. Herein, a type of three-dimensional (3D) hierarchical porous titanium-based microclews composed of one-dimensional (1D) titanium dioxide (TiO2) nanoribbons and SnO2 nanoparicles, is synthesized for the first time with the assistance of cationic surfactant, cetyltrimethylammonium bromidewere (CTAB). SnO2 nanoparticles distribute uniformly on the nanoribbons, and CTAB as growth controller plays a key role in the formation of the uniform and stable hierarchical-structure. The as-synthesized CTAB assisted hierarchical-structure TiO2@SnO2 microclews (CA–TiO2@SnO2 MCs) elelctrode demonstrates outstanding ionic conductivity due to the structure assisting efficient contact between electrode and electrolyte, with a remarkable discharge capacity of 448.3 mAh g−1 after cycling for 500 times at a current density of 500 mA g−1, and a capacity retention of 558.8 mAh g−1 at 200 mA g−1 after 400 cycles in LIBs.

Gradient Polarity Solvent Wash for Separation and Analysis of Electrolyte Decomposition Products on Electrode Surfaces

The solid electrolyte interphase (SEI) formed during the cycling of lithium-ion batteries (LIBs) by decomposition of electrolyte molecules has key impact on device performance. However, the detailed decomposition process and distribution of products remain a mystery due to the wide variety of electrochemical pathways and the lack of facile analytical methods for chemical characterization of SEIs. In this report, a gradient polarity solvent wash technique involving the use of solvents with gradually increased polarities is employed to sequentially remove different SEI components from electrode surfaces. Fourier transform infrared (FTIR) spectroscopy is utilized to characterize the SEI composition. The impacts of electrolyte additives and discharge rates over SEI formation are illustrated. This study presents a new concept of rationally controlled solvent wash technique for electrode surface analysis that can selectively remove targeted components. The findings in this study provide experimental support for the slow charge formation processes commonly employed for LIBs in industry.