Lithium-ion Battery Industry Research Articles

Printed Thin Lithium Foil with Flexible Thickness and Width for Industrial Battery Applications

Lithium metal anodes are attractive for next generation battery technologies due to their high capacity, low voltage potential and light weight.1 The state of the art lithium-ion battery cells have energy density of ~300 Wh/kg. The lithium metal anode has already been used in rechargeable batteries with liquid electrolyte and demonstrated record specific energy density of more than 400 Wh/kg.2 , 3 Solid-state batteries use non-flammable solid electrolytes instead of liquid and therefore offer improved safety. However, solid state batteries can exceed the energy density of today's lithium-ion batteries only when the thin lithium metal foil is used as an anode.The common process to produce thin lithium foils includes extrusion followed by a rolling process. Typically, extruded lithium foil has a thickness of 100 μm or higher and is often made from lithium aluminum or other alloys to improve its mechanical strength. There are inherent difficulties of making extruded and rolled thin lithium metal films with thickness less 50 μm; for example, the control of thickness uniformity over long lengths and impurity levels.4 Moreover, the cost of making these foils increases as the thickness decreases. Thus, thin lithium foils with thickness less than 50 μm haven’t been produced on an industrial scale with the quality requirements necessary for battery applications.Livent Corporation, formerly FMC Lithium, is one of the top lithium producers in the world and has over 60 years of extensive experience in providing high quality materials to the lithium-ion battery industry. Livent has recent developed Printable Lithium Technology (PLT), which incorporates stabilized lithium metal powder (SLMP®) into a stable printable formulation. PLT enables printing on any substrate, for example a current collector, prefabricated anode or cathode, separator, and even on solid or polymer electrolytes. The thickness of printed lithium foil is mainly controlled by the particle size of SLMP. The technology is easily scalable using industry standard coating and printing equipment. PLT is flexible, battery chemistry agnostic and adaptable to any energy storage device where thin lithium anodes are used.Figure 1A shows an image comparing the 50 μm commercially available lithium foil (left) and 20 μm printed lithium foil (right) on a copper current collector. Figure 1A shows that a uniform film made from printable lithium formulation is consistent across the entire 50cm×10cm area. Figure 1B and figure 1C are the optical microscope images of 50 μm commercially available lithium foil and 20 μm printed lithium foil, respectively. Figure 1C shows that printed lithium foil maintains particulate structure of SLMP precursor that potentially can distribute current density over a wider surface area. The thin foil made with printable lithium formulation (PLF) contains rheology and performance modifiers that serve as a 3D skeleton, which can change the lithium surface plating behavior; therefore, mitigating the growth of dendritic lithium and mechanical degradation; thus, improving safety and cycle life of the battery.Figure 1D compares lithium plating and stripping properties conducted in a symmetric pouch cell with a current collector coated with 20 um printed lithium foil vs. 50 um commercially available lithium foil. The symmetric cell contains two Li/Cu electrodes with Celgard 3501 separator sandwiched in between. Figure 2 shows that cell containing the printed lithium foil, and in spite of its lower thickness, has exceptional cycling stability with negligible potential increases during the first 70 cycles, indicating that the growth of dendritic lithium has been significantly mitigated. Fgiure captions: Figure 1A. Image of 50 μm commercially available lithium foil (left) and 20 μm printed lithium foil (right) on a copper current collector. Figure 1B. Microscope image of 50 μm commercially available lithium foil. Figure 1C. Microscope image of 20 μm printed lithium foil. Figure 1D Lithium plating and stripping properties tested in a pouch cell with a copper current collector coated with 20 μm printed lithium foil versus 50 μm commercially available lithium foil. Cycling voltage is between -0.5V and 0.5 V and a current density is 0.5 C for 1h. References D. Lin, Y. Liu, and Y. Cui, Nature Nanotechnology, 12, 194–206 (2017) http://dx.doi.org/10.1038/nnano.2017.16.J. Liu et al., Nature Energy, 4, 180–186 (2019).Q, Hu, Y. Matulevich and Y, Tang, Solidenergy Systems, US Patent No. 16/308,023, June 08th, 2016.O. Mashtalir, M. Nguyen, E. Bodoin, L. Swonger, and S. P. O’Brien, ACS Omega, 3, 181–187 (2018). Figure 1

A quantification method for Fe based particle contaminants in high purity materials for lithium-ion batteries

The technological growth, the increasing safety, and production standards cascade down to the quality of the raw materials. The development of analytical methods for high quality powder analysis needs to grow parallel to this trend. It is established that particle metal contaminants could trigger violent failures of lithium-ion batteries and compromise the battery performance, and the safety of the end user.Increased miniaturization requires exponential increases in quality of raw materials putting laboratories in a continuous process of development to achieve ever higher standards. Trace elements in a powder material can be present in different states, and their effect on the application can therefore be different according to the status. Trace elements can be present in the material as a dissolved impurity or as a particle contamination.Here we present an experimental method which is easy to implement and use, and is sensitive to contaminants (i.e. external particles that are not part of the material of interest) over total trace elements. Contaminants typically are a few orders of magnitude lower in concentration than total trace elements. The method focuses on the quantification of Fe, Ni and Cr in high purity carbon powders used in the lithium-ion battery industry. We present test sample size calculations prior to the method description to ensure high precision and assess possible bias. The method is based on the magnetic extraction of a large test sample, followed by acid digestion and quantification. The procedure and the method performance are described. The method ensures low levels of detection and quantification, high precision, and accuracy.

A comparative life cycle assessment on lithium-ion battery: Case study on electric vehicle battery in China considering battery evolution.

China has become the largest electric vehicle (EV) market in the world since 2015. Consequently, the lithium-ion battery (LiB) market in China is also expanding fast. LiB makers are continually introducing new types of LiBs into the market to improve LiBs' performance. However, there will be a considerable amount of waste LiBs generated in China. These waste LiBs should be appropriately recycled to avoid resources' waste or environmental pollution problems. Yet, because LiBs' type keeps changing, the environmental impact and profitability of the waste LiB recycling industry in China become uncertain. In this research, we reveal the detailed life cycle process of EVs' LiBs in China first. Then, the environmental impact of each type of LiB is speculated using the life cycle assessment (LCA) method. Moreover, we clarify how LiBs' evolution will affect the economic effect of the waste battery recycling industry in China. We perform a sensitivity analysis focusing on waste LiBs' collection rate. We found that along with LiBs' evolution, their environmental impact is decreasing. Furthermore, if waste LiBs could be appropriately recycled, their life cycle environmental impact would be further dramatically decreased. On the other hand, the profitability of the waste battery recycling industry in China would decrease in the future. Moreover, it is essential to improve waste LiBs' collection rate to establish an efficient waste LiB industry. Such a trend should be noticed by the Chinese government and waste LiB recycling operators to establish a sustainable waste LiB recycling industry in the future.

Evaluating the electric vehicle popularization trend in China after 2020 and its challenges in the recycling industry.

In recent years, China has started to develop electric vehicles (EVs) and has become the largest EV market in the world since 2015. Accordingly, the lithium-ion battery (LiB) industry has also been developing quickly in China. However, the Chinese government has decided to cancel the subsidy policy on EVs, which makes the EV market in China unpredictable in the future. Moreover, there will be a considerable number of end-of-life (EoL) EVs and waste LiBs generated in China. These wastes should be appropriately recycled to avoid resource waste or pollution problems. Nevertheless, the quantity and type of EoL EVs and waste LiBs has not been obtained. This research aims at unravelling the trend of EV sales and the volume and type of EoL EVs and waste LiBs in China. We found that it is fair to predict that EVs will increase as the Chinese government has planned even without the subsidy policy. Moreover, we estimated the number of EoL EVs and waste LiBs number based on their calendar lifespan and found that there will be 1.36 million EoL EVs and 11.36 million waste LiBs generated in China in 2030. Furthermore, most of these waste LiBs will be of the nickel cobalt manganese oxide type of ternary LiBs. However, due to the flow of second-hand vehicles from economically developed cities to less economically developed cities, only 400,000 EoL EVs and 3.4 million waste LiBs will be recycled through the formal recycling route. Such information is necessary when evaluating the environmental effect or profitability of the EoL EV and waste LiB recycling industry.

A renewable gel polymer electrolyte based on the different sized carboxylated cellulose with satisfactory comprehensive performance for rechargeable lithium ion battery

Gel polymer electrolyte (GPE) comprising the merits of liquid electrolyte (LE) and solid state electrolyte (SSE) has attracted soaring attention. Herein, we develop a GPE with good comprehensive performance by means of mixing the micro carboxylated cellulose fibril (MCCF) and nano carboxylated cellulose fibril (NCCF) in different proportions. In this composite structure, MCCF forms the skeleton of the host membrane of GPE and provides aplenty pores. While NCCF reinforces the connections of the micron cellulose filaments, enhancing the mechanical properties of the membrane. Obtained from the experimental results, the GPE containing 1%wt nano cellulose exhibits a high tensile strength of 40.1 MPa, a good ionic conductivity of 1.84 mS cm−1 at 25 °C and a stable thermal performance up to 220 °C. Simultaneously, the NCM523//Li half cell assembled with this GPE shows a moderate cyclic performance at the ambient temperature of 25 °C. Moreover, such cellulose based GPE is renewable and biodegradable, which can contribute to the environmental protection-oriented development of lithium ion battery industry.

Simple Approach: Heat Treatment to Improve the Electrochemical Performance of Commonly Used Anode Electrodes for Lithium-Ion Batteries.

The lithium-ion battery (LIB) industry has been in high demand for simple and effective methods to improve the electrochemical performance of LIBs. Here, we treated three different widely studied anode electrodes (i.e., Li4Ti5O12, TiO2, and graphite) under vacuum at 250 °C, and compared their electrochemical performance with and without a 250 °C treatment. Without changing the composition of the fabricated electrodes, all of the 250 °C treated electrodes exhibited enhanced specific capacities, and the lithium-ion diffusion was improved in different degrees. By comparing the results of scanning electron microscopy (SEM) and energy-dispersive spectroscopy of the pristine and 250 °C treated electrodes, the 250 °C treatment improved the distribution of a polyvinylidene difluoride (PVDF) binder in the electrodes, resulting in a higher porosity of the 250 °C treated electrodes. The results of X-ray photoelectron spectrometry and SEM of the cycled electrodes confirmed that a uniform distribution of the PVDF binder from the 250 °C treatment played a positive role in the formation of a solid electrolyte interphase layer, thereby delivering higher capacities and capacity retentions than those of electrodes without heat treatment. The simplicity of this modification method provides considerable potential for building high-performance LIBs at a larger scale.

Recycling and Direct-Regeneration of Cathode Materials from Spent Ternary Lithium-Ion Batteries by Hydrometallurgy: Status Quo and Recent Developments

The cathodes of spent ternary lithium-ion batteries (LIBs) are rich in nonferrous metals, such as lithium, nickel, cobalt and manganese, which are important strategic raw materials and also potential sources of environmental pollution. Finding ways to extract these valuable metals cleanly and efficiently from spent cathodes is of great significance for sustainable development of the LIBs industry. In the light of low energy consumption, ‘green’ processing and high recovery efficiency, this paper provides an overview of different recovery technologies to recycle valuable metals from cathode materials of spent ternary LIBs. Development trends and application prospects for different recovery strategies for cathode materials from spent ternary LIBs are also predicted. We conclude that a highly economic recovery system: alkaline solution dissolution/calcination pretreatment → H2SO4 leaching → H2O2 reduction → coprecipitation regeneration of nickel cobalt manganese (NCM) will become the dominant stream for recycling retired NCM batteries. Furthermore, emerging advanced technologies, such as deep eutectic solvents (DESs) extraction and one–step direct regeneration/recovery of NCM cathode materials are preferred methods to substitute conventional regeneration systems in the future.

Anti-cognition in lithium-ion battery electrolytes: Comparable performance with degraded electrolyte

The stability of electrolytes is extremely important for the lithium-ion battery industry. However, research on electrolyte stability is lacking. Many film-forming additives are investigated to improve the interface stability of the cathode and electrolyte. However, many additives are unstable even in ambient environments, which results in additional costs in electrolyte cryogenic transportation and storage. Herein, we conduct in-depth research on the performance of high-voltage batteries influenced by the stability additives containing electrolytes. The capacity retention is only 44% and 20% after 150 cycles using standard (STD) electrolyte in LiNi0.5Mn1.5O4/Li and xLi2MnO3·(1-x) LiMO2/Li batteries, respectively. Film-forming additives usually promote the cycling performance of batteries. Surprisingly, after storage for 30 days, the batteries with yellowing electrolyte show better cycling performances. The LiNi0.5Mn1.5O4/Li and xLi2MnO3·(1-x) LiMO2/Li batteries achieve 92% and 75% capacity retention with a coulombic efficiency of 99.2% and 99.1% after 150 cycles, respectively, which performs better than fresh electrolyte. Following measurements indicate that the additive decomposition product can contribute to the formation of surface films, which inhibits continuous decomposition of the electrolyte and impedes pulverization of the cathode electrode. This work counters current conceptions of degraded electrolyte and is informative for the industrial applications of unstable additive-containing electrolytes.

Improving the electrochemical performance of LiMn0.8Fe0.2PO4 cathode with nitrogen-doped carbon via dielectric barrier discharge plasma

In this work, the LiMn0.8Fe0.2PO4/nitrogen-doped carbon (LMFP/NC) was fabricated through a facile approach by atmospheric dielectric barrier discharge (DBD) plasma. Applying DBD to dope nitrogen into the carbon allowed fast lithium-ion migration into LiMn0.8Fe0.2PO4. The degree of defect on carbon surface was quantified. LMFP/NC exhibited the initial specific capacity around 124 mAhg−1 at 0.1C. It was demonstrated that DBD could be effectively used in the modification of the lithium-ion battery industry.

Rethinking Chinese supply resilience of critical metals in lithium-ion batteries

With the rapid development of the lithium-ion battery (LIB) industry, the demand for core valuable elements in LIB has increased dramatically. A safe supply of corresponding metals is crucial to ensure the industry’s sustainability. However, quantitative evaluation to reveal the supply risk including criticality of LIBs in China is still not available. In this regard, criticality analysis was carried out to identify the importance of a specific metal in the current LIBs supply chain of raw materials. Subsequently, a comprehensive methodology to evaluate supply sustainability is established in this research by considering the combined effects of material supply, economic fluctuations, and technology innovation in the time frame from 2015 to 2030. An integrated index called Chinese supply resilience is introduced, indicating that a low Chinese supply resilience has a high possibility of supply shortage of the corresponding metal while a high resilience level represents minor supply risk. The results show that insufficient material supply has already induced a severe shortage for lithium (Li) and cobalt (Co). Specifically, Chinese supply resilience of lithium moves from the threshold to the low resilience zone, whereas that for cobalt remains in the low area, both implying a high risk of supply shortage. Furthermore, three appropriate mitigation measures, that is, recycling of spent LIBs, substitution of raw materials, and an increase in domestic raw materials production are considered. Recycling demonstrates the most effective solution to alleviate the potential supply risk of corresponding materials. With this research, it may promote management efficiency on end-of-life LIBs for policy makers.

Ultrasonic renovating and coating modifying spent lithium cobalt oxide from the cathode for the recovery and sustainable utilization of lithium-ion battery

This research presented a sustainable recycling method for the separation and renovation of spent lithium-ion batteries (LIBs) based on the ultrasonic effects. Lithium cobalt oxide (LiCoO2) and aluminum foils were separated sufficiently under the effect of ultrasonic cavitation. The lithium in anode materials was directly reused as lithium leaching solution and applied in the ultrasonic renovation of spent LiCoO2. Thereby solving the problem of wastewater discharge and realizing the whole material circulation. The optimal separation rate was 99.98% under the ultrasonic power of 270 W, the temperature of 75 °C, the ultrasonic time of 120 min, the stirring speed of 200 r·min−1, the solid-liquid (S/L) ratio of 1/140 g mL−1 and 1 mL H2O2 solution. The pH range of the lithium leaching solution were within 10.10–10.64 to realize the optimal renovation effect. Argon (Ar) atmosphere was used as cavitation gas to improve the cavitation effect and increase the renovation efficiency. Nano-Al2O3 was applied for coating modification to improve the electrochemical properties. The first charge and discharge capacity of the modified battery was 167.0 mAh·g−1 and 166.3 mAh·g−1. The process introduced no secondary pollution and showed a high reaction efficiency, which meet the journal scope of sustainable development. This study comprehensively improved the utilized efficiency and provided a theoretical basis for the technical upgrading of the spent LIBs industry.

Research on the Technological Development of Lithium Ion Battery Industry in China

Combined with the background of the rapid development of new energy automobile industry and the power battery gradually becoming the absolute main force of the market in recent years, this paper illustrates the current development status of global and Chinese lithium ion battery industry and analyzes the future development trend of the industry. Focusing on ternary lithium ion battery, all-solid-state lithium ion battery, anode material, lithium hexafluorophosphate electrolyte and diaphragm materials, this paper describes the research and development of different key materials and technologies of lithium ion battery, and gives the prospect of future technology development direction. Based on Chinese lithium ion battery industry background, reasonable industrialization suggestions are put forward.

Supply risks of lithium-ion battery materials: An entire supply chain estimation

Lithium-ion batteries, as the essential technology for global energy transition, require the combined support of several metallic resources and the complicated supply chains that follow. The risk of supply disruptions to these resources has been widely observed and measured. However, system boundaries of previous studies were conventionally limited to the mine stage. Possible supply risks inherent in the downstream processing stages were not adequately taken into account. To fill this gap, we generalize the idea of supply risk to the whole supply chain to describe the comprehensive threats for the steady consumption of lithium-ion batteries. Based on such concept, this study assesses the risks of the lithium-ion battery related materials in the three major stages of the entire supply chain: mining, refining and manufacturing. Results indicate that lithium and cobalt are the most critical materials for lithium-ion battery industry. Risks hidden in the downstream stages of nickel and manganese should also not be overlooked. We further argue that for important energy-related materials with complicated supply chains, the risks should be identified and safeguarded comprehensively throughout the entire supply chain. Such work calls for further database establishment and analysis.

Revealing the Doping Effect in Stabilizing Layered Cathode Materials for Sodium-Ion Battery

Energy storage devices allow us to use energy in a flexible, high efficient and eco-benign way, which has profoundly shaped our everyday life. The most successful energy storage device is lithium-ion battery (LIB), which has dominated the portable electronic devices and are now penetrating deep into vehicle markets. However, the limited reserves of lithium and cobalt in the earth crust cannot fulfill the huge demand gap of electrochemical energy storage, and the fast expansion of LIB industry has already led to accelerated cost rising. Therefore, worldwide research programs strategically encourage the development of energy storage devices beyond LIB, among of which, sodium ion battery (SIB) is a very attractive one. Sodium is much more natural abundance and more importantly SIB industry can share facilities and technologies from LIB because of the similarities of physical and chemical properties between Li and Na. To achieve superior performance of SIB, high performance cathode material plays a critical role. Among of variety of cathode candidates, layered NaxTMO2 (TM refers to transition metal) oxides are promising and widely studied, which can be grouped into two families, P2-type and O3-type structures. However, one critical drawback for both P2-type and O3-type layered oxides is the multi-phase-transition reactions during charge/discharge, which leads to the annoying multi-voltage-plateaus in voltage-capacity profiles. Various ordering processes (TM ordering, charge ordering and Na-vacancy ordering) and structure transitions (P2-O2, O3-P3, et al) have been identified previously. The structural ordering will result in sluggish Na-ion transportation kinetics and it can further couple with the structural transformation to collectively cause structural instability, significantly plaguing the cycling performance. Therefore, many efforts have been taken to suppress the structural ordering and transformation, namely eliminating the multi-voltage-plateaus in the charge/discharge profile. Particularly for P2-Na2/3Ni1/3Mn2/3O2 (NNM), doping electrochemically inactive elements (Li, Mg, Cu or Zn) is proven to be an effective approach to suppress the P2-O2 phase transition and Na-vacancy ordering to achieve improved electrochemical performance. In this work, by virtue of variety of analytical tools, such as X-ray diffraction (XRD), focused ion beam/scanning electron microscopy (FIB/SEM), transmission electron microscopy (TEM) and scanning transmission electron microscopy-high angle annular dark field (STEM-HAADF) imaging, we conduct systematic investigations on the degradation mechanisms of P2-NNM and find that P2-O2 phase transition induced grain cracking is the main cause of performance decay. Our further investigations on the role of dopant on P2-Na0.67Ni0.33-xMn0.67MgxO2 (x=0, 0.05, 0.1) (P2-NMMx) and find that doping electrochemically inactive elements can suppress intragranular cracking to improve cycle stability of P2-NM. we show that dopants segregation is more effectively to suppress intragranular crack and improve cycling stability than dopant uniform distribution in TM layer. By virtue of variety of analytical tools and simulation, dopant segregation have been characterized comprehensively and come up a new strategy, precipitation strengthening mechanism, to alleviate electrochemomechanical degradation and enhance stability of layered cathode operating at high voltage.

Mass produced NaA zeolite membranes for pervaporative recycling of spent N-Methyl-2-Pyrrolidone in the manufacturing process for lithium-ion battery

N-methyl pyrrolidone (NMP) is a colorless and odorless liquid that has been heavily used in the manufacturing process of lithium ion batteries. The development of efficient technology for the on-site recycling of NMP is extremely significant in the lithium ion battery manufacturing plant. The pervaporation dehydration by mass produced NaA zeolite membranes followed by vacuum flash vaporization has proven to be an effective and economic way for recovering spent NMP in this paper. The pilot-scale pervaporation plant containing 225 tubular NaA zeolite membranes with a total membrane area of ca. 7.3 m2 was established for dehydration of actual industrial recovered NMP solution from a lithium battery production line. All technical indicators of the retentate (NMP ≥ 99.9%, H2O ≤ 105 ppm, color 10 Hz, refractive index 1.4694) have fully met the requirements of electronic-grade NMP for lithium-ion battery industry. Owing to the excellent molecular sieving effect of NaA zeolite membrane at extremely low water concentration, the NMP recovery yield was far better than the reported values in literature. These results suggested that the mass produced NaA zeolite membranes showed technical feasibility for the recycling of NMP in the lithium ion battery manufacturing process.

Investigation of Lithium-Ion Battery Interface Degradation Mechanism through EIS Analysis Under Various Cycling Conditions

Lithium-ion batteries have attracted enormous attention in the past decade both in the academia and in the industry due to their extreme high energy and power density compared with the conventional battery systems. Stepping into 2019, the lithium-ion battery industry unprecedentedly focuses on the fast charging and diagnosis solutions, especially for the dynamic battery systems. However, the complicated environmental conditions, such as vibration, extreme temperature change, overcharging or overdischraging, fast charging, various testing techniques, combined with insufficient understanding of the State of Health (SOH) of the commercial batteries lead to thermal runaway, aging and explosion issues to the batteries. Stemmed from that fact, EIS (Electrochemical Impedance Spectroscopy) technique has been proposed to accurately determine the SOH of the commercial batteries. EIS has been proved to be an effective approach to investigate the electrochemical, structual and dynamical properties of the electrochemical systems, especially the interfaces. The study focuses on the effects of one of the most concerning technique "fast charging" and one testing technique, GITT (Galvanostatic Intermittent Titration Technique). Under pre-design conditions, EIS with pre-built equivalent circuit is then implemented at specific conditions to further gather the electrochemical and structural properties of the interfaces inside the battery at proper voltages. Finally, the electrochemical and structual degradation mechanism especially of the interfaces under various conditions is achieved, which inspires further investigation on the comprehensive analysis and determination of the SOH of the lithium-ion batteries. The proposed approach has shown better accuracy and more in-depth analysis compared with the existing techniques.

Comparative study on the electrochemical performance of LiFePO4 cathodes fabricated by low temperature 3D printing, direct ink writing and conventional roller coating process

Electrodes for lithium-ion batteries can be fabricated in many ways including conventional roller coating and 3D printing. Roller coating is a standardized process in current lithium-ion battery industry, while 3D printing has been used to fabricate three-dimensional (3D) unconventional electrodes with tailored geometries. Our previous study proposed a low temperature 3D printing process to fabricate highly-porous LiFePO4 (LFP) electrodes. However, there still lack a study on the comparison of electrochemical performance of LFP electrodes fabricated via the three different fabrication processes including low temperature direct writing-based 3D printing (LTDW), room temperature direct ink writing (DIW) and roller coating process. In this study, we fabricated LFP cathodes using these three fabrication processes from LFP inks with different solid contents. By varying the solid content, LFP electrodes with different geometries (including width and thickness), morphologies and porous microstructures were obtained via LTDW and DIW. Mercury porosimetry was performed to examine the differences of the three types of LFP electrodes in porous microstructures. Electrochemical performance including charge/discharge, rate performance, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) of the three types of electrodes were measured and compared. Results showed that electrode fabrication processes have important effects on the electrochemical performance of LFP electrodes depending on the ink solid content. LTDW-fabricated electrodes had the best performance at high solid content (≥0.467 g/mL) and conventional roller coated electrodes performed better at low solid content (≤0.356 g/mL). Relationships between ink solid content, fabrication process, resulting porous microstructures and electrochemical performance were discussed. Finally, an optimal specific capacity of ∼82 mAh.g-1 @ 10C was achieved at a solid content of 0.467 g/mL by LTDW process.

Correlation between the physical parameters and the electrochemical performance of a silicon anode in lithium-ion batteries

Lithium-ion battery anode used as silicon particles were obtained from different major suppliers, and they were characterized by different spectroscopic techniques and evaluated by electrochemical experiments. Correlations between the key physical parameters and electrochemical properties of the silicon particles were investigated. Silicon particle size, surface oxygen content, -OH content and physical appearance are found to strongly influence the electrochemical properties of the Si anode. The particle size of 100 nm has great promise for the practical application of Si nanoparticles in the lithium-ion battery industry. An inverse correlation between the oxygen content and the reversible capacity or first coulombic efficiency was obtained. The -OH content by surface treatment contributes to enhanced cycling stability by the improved affinity between the Si particle and the water-soluble binder. Spherical Si particles perform better compared to irregular particles, and agglomeration dramatically decreases the cycling stability of the Si anode. Among the investigated Si particles, the sample that exhibited a reversible capacity of more than 2500 mAh g−1, a first coulombic efficiency of 89.26% and an excellent cycling stability, has great potential for use in the battery industry.

Improving the processability and cycling stability of nano-LiFePO4 cathode by using PVDF/TX binary binder

ABSTRACTIn lithium-ion battery industry, the nanoscale electrode materials usually have difficulty to be dispersed well in the electrode slurry. The inferior processability thus results in deteriorated electrochemical performances of the cell. In this work, poly(vinylidene fluoride) (PVDF) and terpene resin (TX) as a binary binder are used to improve the dispersibility and cycling stability of nanoscale LiFePO4 (nano-LFP) cathode. The wettability, dispersibility, adhesion strength and electrochemical performance of nano-LFP cathode using PVDF/TX are measured and compared with that using only PVDF binder. Nano-LFP cathode using PVDF/TX binder (the optimal ratio of PVDF to TX is 97:3) exhibits better dispersibility and stronger adhesion strength than that of PVDF. In addition, nano-LFP cathode with PVDF/TX binder shows better cycling stability, rate capability, and electrochemical kinetics than that with PVDF, retaining 97.4% capacity after 100 cycles test at C/5 in room temperature and 93.4% capacity after 60 cycles test at C/2 in 55℃, respectively.

(Keynote) A Path Forward to Low-Cobalt or Cobalt-Free Cathodes for Lithium-Ion Batteries

Lithium-ion batteries have become the choice of power source for portable electronics as they offer much higher energy density than other rechargeable systems. They are also in the process of transforming the transportation sector and beginning to penetrate the utility industry for grid storage of electricity produced from renewable sources like solar and wind. The lithium-ion battery industry is now based on layered LiMO2 cathodes with fractions of M = Mn, Co, and Ni as each of them has its own advantages and disadvantages. For example, Mn offers good chemical stability without oxygen release, while Co suffers from oxygen release on charging LiCoO2 beyond ~ 50% as the Co3+4+: t2g band overlaps with the top of the O2-:2p band. In contrast, Co offers good structural stability without migrating from the transition-metal layer to the lithium layer via the neighboring tetrahedral sites due to the high octahedral-site stabilization energy, while Mn migrates readily to the lithium layer resulting in a layered to spinel-like phase transition due to the low octahedral-site stabilization energy. Also, Mn is abundant, environmentally benign, and less conductive, while Co has limited abundance, is relatively toxic, and becomes metallic on charging. Ni is in between Co and Mn in all these criteria. To make use of the best out of each of these three ions, the industry is now based on LiNi1-y-zMnyCozO2 with (1-y-z) < 0.6 and a significant fraction of Co (z > 0.2). There is a significant drive to reduce the fraction of Co or eliminate it altogether and increase the fraction of Ni. However, LiMO2 cathodes with a high fraction of Ni suffer from a few serious issues: capacity fade, thermal instability, and air-reactivity due to (i) a series of phase transitions causing internal stress, (ii) high surface reactivity with the electrolyte resulting in the formation of thick solid-electrolyte interphase, and (iii) high surface reactivity with ambient air resulting in a significant amount of LiOH and LiHCO3 on the surface. This presentation will first focus on a fundamental understanding of the bulk and surface instability of layered LiMO2 cathodes, employing advanced characterization tools, such as time-of-flight secondary ion mass spectrometry, x-ray photoelectron spectroscopy, and aberration-corrected transmission electron microscopy, to probe both the layered oxide cathode and graphite anode subjected in full lithium-ion cells to extended cycling (up to 1,500 cycles). The presentation will then focus on developing LiMO2 cathodes with a cobalt content of as low as 6% with appropriate cationic doping and surface stabilization. Finally, it will also present a path forward to develop cobalt-free LiMO2 cathodes. Based on the strategies, cathodes with capacities of as high as 220 mAh/g with good cycle life and air stability will be presented.