Capacity Li-ion Batteries Research Articles

Two-dimensional B3P monolayer as a superior anode material for Li and Na ion batteries: a first-principles study

The pursuit for increasing storage capacities of metal ion batteries is directly linked with the search for technologically superior next generation electrode materials. In this context, ab-initio first-principles calculations provide the means for exploring and designing novel 2D materials that can enhance energy storage capacities. In this work, we employ density functional theory calculations to draw a rationale for graphene-like B3P monolayer which shows high dynamical, thermal and mechanical stability. Our calculations predict larger cohesive energies of 2D B3P monolayer as compared to the well-known 2D boron-phosphide and recently predicted borophosphene, indicating its easy experimental synthesis as a graphene-like monolayer. Using both DFT and the thermodynamic energy decomposition scheme, we show that B3P with large lattice parameters and intrinsic metallicity is a potentially excellent 2D material for applications in energy storage devices. The results of our first-principles calculations designate B3P as a superior anode material owing to its high theoretical capacity for both Li and Na ion batteries combined with good open-circuit voltages and low metal ion migration barriers for Li and Na ions. Furthermore, sustained metallicity and thermal stability under loaded intermediate metal ion content indicates B3P monolayer to be a promising 2D material for extending battery operating cycles.

Sp2/sp3 Hybridized Carbon as an Anode with Extra Li-Ion Storage Capacity: Construction and Origin.

Doping in carbon anodes can introduce active sites, usually leading to extra capacity in Li-ion batteries (LIBs), but the underlying reasons have not been uncovered deeply. Herein, the dodecahedral carbon framework (N-DF) with a low nitrogen content (3.06 wt %) is fabricated as the anode material for LIBs, which shows an extra value of 298 mA h g–1 during 250 cycles at 0.1 A g–1. Various characterizations and theoretical calculations demonstrate that the essence of the extra capacity mainly stems from non-coplanar sp2/sp3 hybridized orbital controlling non-Euclidean geometrical structure, which acts as new Li-ion active sites toward the excess Li+ adsorption. The electrochemical kinetics and in situ transmission electron microscope further reveal that the positive and negative curvature architectures not only provide supernumerary Li+ storage sites on the surface but also hold an enhanced (002) spacing for fast Li+ transport. The sp2/sp3 hybridized orbital design concept will help to develop advanced electrode materials.

Analysis of nanostructured cobalt ion beam-modified Ge surface for high capacity Li-ion battery anodes by X-ray photoelectron spectroscopy

The results of the study of nanostructured germanium (Ge), intended for its subsequent use as electrodes of lithium-ion batteries are presented. Single-crystal germanium plate was irradiated by cobalt ions with an energy of 40 keV in the dose 4×1016 Co+ / cm2 for the nanostructuring. The changes in the elemental composition occurring during the electrochemical lithiation of manufactured germanium electrode were investigated by X-ray photoelectron spectroscopy (XPS).

A Commercial Carbonaceous Anode with a-Si Layers by Plasma Enhanced Chemical Vapor Deposition for Lithium Ion Batteries

In this study, we propose a mass production-able and low-cost method to fabricate the anodes of Li-ion battery. Carbonaceous anodes, integrated with thin amorphous silicon layers by plasma enhanced chemical vapor deposition, can improve the performance of specific capacity and coulombic efficiency for Li-ion battery. Three different thicknesses of a-Si layers (320, 640, and 960 nm), less than 0.1 wt% of anode electrode, were deposited on carbonaceous electrodes at low temperature 200 °C. Around 30 mg of a-Si by plasma enhanced chemical vapor deposition (PECVD) can improve the specific capacity ~42%, and keep coulombic efficiency of the half Li-ion cells higher than 85% after first cycle charge-discharge test. For the thirty cyclic performance and rate capability, capacitance retention can maintain above 96%. The thicker a-Si layers on carbon anodes, the better electrochemical performance of anodes with silicon-carbon composites we get. The traditional carbonaceous electrodes can be deposited a-Si layers easily by plasma enhanced chemical vapor deposition, which is a method with high potential for industrialization.

Nondestructive High-Sensitivity Detections of Metallic Lithium Deposited on a Battery Anode Using Muonic X-rays.

Metallic Li deposited on the anode is known to induce short circuiting and degradation of the charge capacity of Li-ion batteries. However, no reliable technique is currently available to observe such Li metal without removing the case of the battery. An elemental analysis using muonic X-rays is proposed here because of its unique properties of nondestructive measurement, high sensitivity to light elements, and depth resolution. We demonstrated that this technique can be applied to detection of Li deposited on the surface of an anode containing Li ions, using a fully charged anode with Li deposited due to overcharge in an Al-laminated plastic pouch. The basis for the detection method is the difference in the atomic Coulomb capture ratio of the negative muons between the Li metal and ions. We have found, as a result, that the intensity of the muonic X-rays from metallic Li was approximately 50 times higher than that from Li ions. Consequently, the Li metal on the anode was clearly distinguishable from the intercalated Li ions in the anode. Furthermore, measurements of two overcharged anodes with 1.3 and 2.7 mg of metallic Li deposition, respectively, indicated that this technique is suitable for quantitative analysis. Distribution analysis is also possible, as shown by a preliminary observation on an overcharged anode from the back side. Therefore, this technique offers a new approach to the analysis of Li deposited on the anode of a Li-ion pouch battery.

Microstructual and Chemical Analysis of Surface Treated Metal Foam Anode for Li Rechargeable Battery

As the amount of power consumed by electronic products increases, a lot of studies focused on high capacity and miniaturization of batteries. In order to overcome the low capacity of carbon anode in Li rechargeable battery, researches on the development of high capacity anode material have been conducted. In particularly, it has been reported that pure lithium was adopted for high capacity of Li ion battery due to its light in weight and excellent theoretical capacity. However, when pure lithium is used, the capacity decreases rapidly as charging and discharging proceeded, which is reported to be formation of dendrite on the Li surface during charging/discharging. In order to suppress the growth of dendrite during charging/discharging, several researches have been focused on the Li impregnated metal foam for Li rechargeable battery. However, due to the poor wettability between metal foam and pure Li, adhesive materials had to be deposited by using expensive processes such as chemical vapor deposition to impregnate the Li into metal foam. In this study we focus on the heat treatment effect on the microstructure and Li-impregnation property of Ni metal foam. We oxidized the metal foam in a high temperature(500-900oC) for 5 min using the furnace to improve the wettability between the Lithium and Ni metal foam. Heat treated metal foam was dip into melted Li at 400 oC in a glove box. As a result, the rate of Li-impregnation in the heat treated metal foam was more than 10 times faster than that of the untreated Ni metal foam. The surface of heat treated Ni metal foam was characterized using transmission electron microscopy (TEM) equipped with energy dispersive X-ray spectroscopy(EDS). Figure. 1 shows the TEM image of the untreated and heat treated Ni metal foam surface. It reveals that an additional layer having a thickness of 200 nm was observed in the heat treated Ni foam. The additional layer was identified as polycrystalline NiOx by EDS and selected area diffraction pattern (SADP). It is believed that formation of NiOx was greatly contribute to improvement of the impregnation characteristics. In addition, the impregnation characteristics of Ni alloy foam will be discussed in this presentation. Figure 1

Electrochemical Study of Li-Ion Battery Anode (Graphite) and Cathode (NMC811) Surface Film Formation By in-Situ Scanning Probe Microscopy

Lithium ion battery usage has grown significantly in recent years. To obtain the best from the li-ion battery technology, it is important to understand both advantages and the limitations from the fundamental point of view. In lithium-ion batteries, layer structured graphite is the most commonly used anode material and NMC is one of the modern choices of cathode materials for high capacity Li-ion batteries in the electric vehicle applications [1,2,3].During the first charging process, the electrochemical reduction of electrolyte components gets deposited on the surface of anode resulting solid electrolyte interface (SEI) layer formation [4,5,6]. It is widely accepted that the batteries benefit from a proper SEI formation, as it can improve their lifetime, cycle life, power capability and safety [7].Morphological structure of SEI layer formed on HOPG and cathode electrolyte interface (CEI) layer formed on NMC plays an important role in lithium-ion battery (LIB), particularly for its cyclability and safety. For the development of high-performance LIB’s, it is crucial to understand the SEI layer formation on anode side [8] and the less studied corresponding layer formed on cathode side termed as CEI, whose composition and role are debated [9].Microscopic techniques, which include scanning tunneling microscopy (STM) and atomic force microscopy (AFM) are the most powerful tools to measure the electric current and surface topography [10,11]. Within this work, we present in-situ electrochemical atomic force microscopic (EC-AFM) studies of surface reaction and topographic evolution of SEI and CEI layers formed on HOPG and NMC811 substrates. EC-AFM morphological analysis is also complemented with XPS (X-ray Photoemission Spectroscopy) characterisation for elemental composition, which brings a new insight in the comparison of SEI/CEI decomposition products. Acknowledgements: This work is partially supported by Faraday Institution (EP/S003053/1) and North-East Centre of Energy Materials-NECEM (EP/R021503/1) funded by EPSRC.

Interconnected conductive gel binder for high capacity silicon anode for Li-ion batteries

A new design for conjugation and crosslinking combined with a conjugated polymer and its application for high capacity Li-ion battery are demonstrated. Polyfluorene (PF), poly(phenylene) (PP), with lateral substituents, namely carboxylic acids, as a potential building block for conjugation was synthesized and characterized. The synthesis was achieved through Suzuki polycondensation reaction in the presence of Pd(PPh3)4 catalyst by using dibromo benzoic acid in conjunction with dioctylfluorene-diboronic acid bis(1,3-propanediol) ester. Thermal chemical cross-linking between carboxylic acid in the polymer backbone and free hydroxyl groups in poly(vinyl alcohol) (PVA) has been performed in the presence of Si. This approach enables a polymer binder with multi-functionality providing a high electronic conductivity and good cycling stability. Overall, we report on a Si-anode with capacity of 1932 mAh/g at C/3, demonstrating the improvement of the electrode using gel polymer binder.

Prelithiation of silicon/graphite composite anodes: Benefits and mechanisms for long-lasting Li-Ion batteries

Prelithiation of silicon/graphite-based composite anodes is a promising strategy to limit Li-ion battery capacity loss over long cycling. We report on the spontaneous-corrosion-driven-lithiation (SCDL) of lithium metal on the anode surface of a-Si/c-FeSi2/graphite//LiNi0·6Mn0·2Co0·2O2 cells, and compare it to electrochemically-driven-lithiation (EDL). High cyclability performances are achieved, i.e. more than 1760 cycles at 100% depth-of-discharge with less than 11% capacity loss at C/2. To quantify the fate of the lithium supply over prolonged cycling and follow in situ the benefits of prelithiation, we perform simultaneous operando synchrotron wide-angle and small-angle X-ray scattering (WAXS/SAXS). By accessing both the graphite lithiation process (WAXS) and the nanostructural variations of the silicon phase (SAXS), we obtain a complete picture of the lithium repartition during lithiation/delithiation of the prelithiated anode. Results indicate that the additional lithium is stored in the silicon, which acts as a reservoir compensating for lithium trapping. The silicon phase therefore plays an essential role but without the detrimental effect of large volume variations. By design, SCDL leads to a more heterogeneous prelithiation compared to EDL given that only the electrode area directly in contact with the lithium metal is initially prelithiated. However, we show that during cycling the additional lithium is redistributed throughout the electrode by migrating into the silicon and, finally, the two methods yield equivalent systems, with similar electrode morphologies and a much increased cell performance over cycling. Prelithiation could therefore be used for the production of high energy density and highly stable Li-ion batteries, implementing the easily up-scalable SCDL process.

High mass loading additive-free LiFePO4 cathodes with 500 μm thickness for high areal capacity Li-ion batteries

We report the preparation of thick ceramic electrodes of the olivine LiFePO4 (LFP) with high mass loading. These electrodes are preparated by means of Powder Extrusion Moulding (PEM), which is a technology easily scalable and cheap. These LFP cathodes are additive-free (neither binder nor extra carbon black) with ~0.5 mm thickness, allowing to develop very high areal capacity (13.7 mA h cm−2). By means of a strict control of sintering process, the carbon coating of the commercial LFP powder remains and the decomposition of the active material is prevented. The optimized self-supported LFP cathode presents good cyclability over 20 cycles at C/10 with no capacity loss. The good electrochemical performance of these novel LFP thick electrodes and their non-flammability make them interesting candidates for both mobile and stationary applications.

Thermal and economic analysis of hybrid energy storage system based on lithium-ion battery and supercapacitor for electric vehicle application

A hybrid electrical energy storage system (EESS) consisting of supercapacitor (SC) in combination with lithium-ion (Li-ion) battery has been studied through theoretical simulation and experiments to address thermal runaway in an electric vehicle. In theoretical simulation, the working temperature of Li-ion battery and SC has been varied from 0 to 75 °C in steps of 25 °C and the effect of the variation is observed on the output current, voltage and power of Li-ion battery and SC for a calculated load using the standard driving cycle. Further, electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) have been performed to investigate the effect of temperature on SC. EIS measurements of SC indicate a low equivalent series resistance of 0.095 Ω at 25 °C. CV measurements indicate a high value of capacitance of 56.65 F/g at 25 °C for a scan rate of 5 mV s−1. Through theoretical simulation of EESS, a temperature increase ( $$ \Delta T $$ ) of 0.41 °C is calculated considering an initial peak of 10-s duration for the case of EESS without SC, whereas the use of SC reduces $$ \Delta T $$ to 0.025 °C. Further, optimal size calculation for hybrid EESS is done to achieve the least cost, wherein Li-ion battery capacity has been varied from 0 to 200 Ah and the SC capacity has been varied from 0 to 5 F in MATLAB simulation. The optimal combination is obtained as 30 Ah capacity of Li-ion battery and 3 F capacity of SC by connecting load across hybrid EESS for a duration of 3600 s.

Colloidal Antimony Sulfide Nanoparticles as a High-Performance Anode Material for Li-ion and Na-ion Batteries

To maximize the anodic charge storage capacity of Li-ion and Na-ion batteries (LIBs and SIBs, respectively), the conversion–alloying-type Sb2S3 anode has attracted considerable interest because of its merits of a high theoretical capacity of 946 mAh g−1 and a suitable anodic lithiation/delithiation voltage window of 0.1–2 V vs. Li+/Li. Recent advances in nanostructuring of the Sb2S3 anode provide an effective way of mitigating the challenges of structure conversion and volume expansion upon lithiation/sodiation that severely hinder the Sb2S3 cycling stability. In this context, we report uniformly sized colloidal Sb2S3 nanoparticles (NPs) as a model Sb2S3 anode material for LIBs and SIBs to investigate the effect of the primary particle size on the electrochemical performance of the Sb2S3 anode. We found that compared with microcrystalline Sb2S3, smaller ca. 20–25 nm and ca. 180–200 nm Sb2S3 NPs exhibit enhanced cycling stability as anode materials in both rechargeable LIBs and SIBs. Importantly, for the ca. 20–25 nm Sb2S3 NPs, a high initial Li-ion storage capacity of 742 mAh g−1 was achieved at a current density of 2.4 A g−1. At least 55% of this capacity was retained after 1200 cycles, which is among the most stable performance Sb2S3 anodes for LIBs.

Nitrogen Doped Multi-channel Graphite for High Rate and High Capacity Li Ion Battery

Nitrogen doped multi-channel graphite was successfully prepared by using nitrogen doping and KOH etching technologies. The three-electrode and EIS tests indicates that the etched graphite possesses lower electrochemical resistance than the pristine graphite. The coin cell tests demonstrate that N doped multichannel graphite possesses a specific capacity of 361 mAh/g and coulombic efficiencies of 91.4%. No dramatic irreversible capacity loss results from the increased specific surface area (from 1.60 to 2.08 m2/g), removing the need for a trade-off between irreversible capacity loss and surface area. Full polymer cells were fabricated and electrochemical capabilities were measured. In 3C fast charge protocol, the charging capacity can reach 51% within 10 min charge, and 100% within 30 min, demonstrating excellent fast charging characteristic. The fast charge cycle performance with 3C-rate charge and 1C-rate discharge from 4.35-3.0 V was conducted at RT temperature. The capacity retention is 94% after 600 cycles, which shows good cycle performance.

One-Pot Synthesis of Lithium Nickel Manganese Oxide-Carbon Composite Nanoparticles by a Flame Spray Pyrolysis Process

The nanoparticles based on nickel-manganese oxide and carbon-coated LiNi0.5Mn1.5O4 are synthesized by flame spray pyrolysis technology with controlled particle sizes. The structural properties of nanoparticles are characterized by X-ray diffraction and high-resolution electron microscopy. It is observed that the higher surface tension of precursors in the flame spray pyrolysis setup increases the particle sizes. The post annealing treatment significantly enhances the crystallinity of nanoparticles due to the favorable oxidation process and the structure conversion from NiMn2O4 to NiMnO3. In addition, the solid-state reaction of as-prepared NiMn2O4 results in the LiNi0.5Mn1.5O4 nanoparticles which can be applied to the cathode in Li-ion batteries. The carboncoated LiNi0.5Mn1.5O4 nanoparticles are also made by additional carbonization reaction. The control of surface tension of precursors in the flame spray pyrolysis process is expected to result in the small size of nanoparticles, which can result in high cyclic stability and high capacity for Li-ion batteries.

Cover Picture: A Redox‐Active 2D Metal–Organic Framework for Efficient Lithium Storage with Extraordinary High Capacity (Angew. Chem. Int. Ed. 13/2020)

2D conjugated MOFs offer a versatile platform for new electronic and energy storage devices. In their Communication on page 5273, E. Hu, Y. Xu, L. Chen, and co-workers report a semiconductive copper-benzoquinoid 2D MOF (Cu-THQ) with extraordinary high capacity for Li-ion batteries. The Li storage mechanism was further elucidated in situ by comprehensive spectroscopic analysis during the charge–discharge process.

The oxygen vacancy in Li-ion battery cathode materials

The substantial capacity gap between available anode and cathode materials for commercial Li-ion batteries (LiBs) remains, as of today, an unsolved problem. Oxygen vacancies (OVs) can promote Li-ion diffusion, reduce the charge transfer resistance, and improve the capacity and rate performance of LiBs. However, OVs can also lead to accelerated degradation of the cathode material structure, and from there, of the battery performance. Understanding the role of OVs for the performance of layered lithium transition metal oxides holds great promise and potential for the development of next generation cathode materials. This review summarises some of the most recent and exciting progress made on the understanding and control of OVs in cathode materials for Li-ion battery, focusing primarily on Li-rich layered oxides. Recent successes and residual unsolved challenges are presented and discussed to stimulate further interest and research in harnessing OVs towards next generation oxide-based cathode materials.

Towards high-volumetric performance of Na/Li-ion batteries: a better anode material with molybdenum pentachloride–graphite intercalation compounds (MoCl5–GICs)

MoCl5–GICs are demonstrated as advanced anodes for simultaneously achieving high volumetric capacity and long cycle life in Na-ion and Li-ion batteries, owing to a strong charge transfer chemical doping effect and strong interaction force between MoCl5 and graphite layers.

Li-Ion Batteries Parameter Estimation With Tiny Neural Networks Embedded on Intelligent IoT Microcontrollers

Lithium-ion (Li-Ion) batteries are rechargeable batteries which can maximize battery lifespan thanks to their chemical abilities, at the same time increasing power energy density. For these reasons, Li-Ion batteries have earned considerable popularity, and they are widely used both in mobile computing devices (e.g. smartphones and smartwatches) and automotive systems (e.g. hybrid and electric vehicles). A fundamental parameter for battery health monitoring is the State of Health (SoH), which is computed from the maximum releasable capacity, and which represents battery functionality in energy storage and delivery. Among the most used data-driven approaches are Machine Learning (ML) algorithms, such as Support Vector Machines (SVMs), Random Forest (RF) regressions, and Artificial Neural Networks (ANNs). This article presents a comparison of different ML algorithms for estimating maximum releasable capacity of Li-Ion batteries, with a special focus on the implementation of both Forward and Recurrent ANNs (FNNs and RNNs, respectively), using prognostic Li-Ion battery data sets provided by the National Aeronautics and Space Administration (NASA). After an evaluation of models performances in terms of RMSE and MAE, STM32Cube.AI tool was used to convert pre-trained ANNs to optimized ANSI C code for STM32 microcontrollers (MCUs), and to profile their complexity automatically. Finally, in order to decrease models size with minimal accuracy loss, the implemented ANNs were quantized via STM32Cube.AI, converting weights and activations from 32-bit floating-point to 8-bit integer precision. TensorFlow Lite for Microcontrollers (TFLM) was used as benchmark in the analysis and validation of both non-quantized and quantized models, and the performances obtained via STM32Cube.AI and TFLM were compared.

Using nanoconfinement to inhibit the degradation pathways of conversion-metal oxide anodes for highly stable fast-charging Li-ion batteries

Nanostructured hybrids that physically encapsulate highly morphable, high capacity Li-ion battery anodes can potentially enable much longer cycle life than straightforward deployment of the same chemistry.

Self-assembly Nb2O5 microsphere with hollow and carbon coated structure as high rate capability lithium-ion electrode materials

Maintaining the high capacity of Li-ion batteries (LIBs) at the high rates is very important for electrode materials. Nb2O5 material, having high power density, is a promising high performance electrode material. However, the poor electrical conductivity and the sluggish Li-ion diffusion kinetic hinder it as anode material for LIBs. In this work, hollow Nb2O5 microsphere and carbon-coated Nb2O5 microsphere are synthesized by the solvothermal method with subsequent heat treatment in air and argon, respectively. The electrochemical tests show that the hollow Nb2O5 microsphere and the carbon-coated Nb2O5 microsphere exhibit the high reversible capacities and high rate capability. Meanwhile, due to the high specific surface area and electrical conductivity, the carbon-coated Nb2O5 microsphere shows better electrochemical performance than the hollow Nb2O5 microsphere, and has high rate capability (193 mAh g−1 and 119 mAh g−1 at the current density of 0.1 A g−1 and 5 A g−1) with the retention of 63%. This kind of novel Nb2O5 structure with high rate performance has potential as anode material for high-power LIBs.