Synthesis Of Cathode Materials Research Articles

Review on the Polymeric and Chelate Gel Precursor for Li-Ion Battery Cathode Material Synthesis.

The rapid design of advanced materials depends on synthesis parameters and design. A wide range of materials can be synthesized using precursor reactions based on chelated gel and organic polymeric gel pathways. The desire to develop high-performance lithium-ion rechargeable batteries has motivated decades of research on the synthesis of battery active material particles with precise control of composition, phase-purity, and morphology. Among the most common methods reported in the literature to prepare precursors for lithium-ion battery active materials, sol-gel is characterized by simplicity, homogeneous mixing, and tuning of the particle shape. The chelate gel and organic polymeric gel precursor-based sol-gel method is efficient to promote desirable reaction conditions. Both precursor routes are commonly used to synthesize lithium-ion battery cathode active materials from raw materials such as inorganic salts in aqueous solutions or organic solvents. The purpose of this review is to discuss synthesis procedure and summarize the progress that has been made in producing crystalline particles of tunable and complex morphologies by sol-gel synthesis that can be used as active materials for lithium-ion batteries.

Optimization of LiNiCoMnO2 Cathode Material Synthesis Using Polyvinyl Alcohol Solution Method for Improved Lithium-Ion Batteries.

The growing need for lithium-ion batteries, fueled by the widespread use of electric vehicles (EVs) and portable electronic devices, requires high energy density and safety. The cathode material Li1-x(NiyCozMn1-y-z)O2 (NCM) shows promise, but attaining high efficiency necessitates optimization of both composition and manufacturing methods. Polycrystalline LiNiCoMnO2 powders were synthesized and assessed in this investigation using a polyvinyl alcohol (PVA) solution method. The study examined different synthesis conditions, such as the PVA to metal ions ratio and the molecular weight of PVA, to assess their influence on powder characteristics. Electrochemical analysis indicated that cathode materials synthesized with a relatively high quantity of PVA with a molecular weight of 98,000 exhibited the highest discharge capacity of 170.34 mAh/g and a high lithium-ion diffusion coefficient of 1.19 × 10-9 cm2/s. Moreover, decreasing the PVA content, irrespective of its molecular weight, led to the production of powders with reduced surface areas and increased pore sizes. The adjustments of PVA during synthesis resulted in pre-sintering observed during the synthesis process, which had an impact on the long-term stability of batteries. The electrodes produced from the synthesized powders had a positive impact on the insertion and extraction of Li+ ions, thereby improving the electrochemical performance of the batteries. This study reveals that cathode materials synthesized with a high quantity of PVA with a molecular weight of 98,000 exhibited the highest discharge capacity of 170.34 mAh/g and a high lithium-ion diffusion coefficient of 1.19 × 10-9 cm2/s. The findings underscore the significance of optimizing methods for synthesizing PVA-based materials to enhance the electrochemical properties of NCM cathode materials, contributing to the advancement of lithium-ion battery technology. The findings underscore the significance of optimizing methods for synthesizing PVA-based materials and their influence on the electrochemical properties of NCM cathode materials. This contributes to the continuous progress in lithium-ion battery technology.

Recovery of Lithium from Industrial Li-Containing Wastewater Using Fluidized-Bed Homogeneous Granulation Technology

In this study, a novel fluidized-bed homogeneous granulation (FBHo-G) process was developed to recover lithium (Li) from industrial Li-impacted wastewater. Five important operational variables (i.e., temperatures, pH, [P]0/[Li]0 molar ratios, surface loadings, and up-flow velocities (Umf)) were selected to optimize the Li recovery (TR%) and granulation ratio (GR%) efficiencies of the process. The optimal operational conditions were determined as the following: a temperature of 75 °C, pH of 11.5, [P]0/[Li]0 of 0.5, surface loading of 2.5 kg/m2·h, and Umf of 35.7 m/h). The TR% and GR% at optimal condition could be as much as 90%. The material characterization of the recovery pellet products showed that they were highly crystallized Li3PO4 (purity ~88.2%). The pellets had a round shape and smooth surface with an average size of 0.65 mm, so could easily be stored and transported. The high purity enables them to be further directly reused as raw materials for a wide range of industrial applications (e.g., in the synthesis of cathode materials). Our calculation shows that the FBHo-G process could recover up to 0.1845 kg of lithium per cubic meter of Li-containing wastewater, at a recovery rate of ~90%. A brief technoeconomic analysis shows that FBHG process had economic viability, with an estimate production cost of USD 26/kg Li removed, while the potential gained profit for selling lithium phosphate pellets could be up to USD 48 per the same volume of wastewater and the net profit up to USD 22/m3 Li treated. In all, fluidized-bed homogeneous granulation, a seedless one-step recovery process, opens a promising pathway toward a green and sustainable recycling industry for the recovery and application of the resource-limited lithium element from nonconventional water sources.

Microwave Plasma Synthesis of Cathode Material for Lithium-Ion Batteries

Among LiB cathode materials, lithiated NMC (Li1Ni(1-x-y)MnxCoyO2) formulations with ≥90% nickel have the potential to increase the specific capacity of LiBs, which is the most direct route to increasing the energy density of the battery. Lithiated NMC (LiNixMnyCo (1-x-y)) has the α-NaFeO2-type crystal structure of LiCoO2, but is chemically more evolved; nickel and manganese are substituted for cobalt, decreasing toxicity and expense, and increasing specific capacity [1-3]. Pristine 90% Nickel-rich cathode material frequently performs with a baseline cycling stability of ~75% over 50 cycles, regardless of synthesis method [4, 5]. NMC morphology is described as having secondary particles made up of many smaller primary particles, which is advantageous to packing density when in application- the best performing materials report secondary particle size of up to 20 μm, with primary particle size of ≤ 1 μm [6]. Fig. 1. Particle morphology of secondary particles up to ~20μm made up of primary particles ≤1μm. Microwave plasma at atmospheric pressure provides a facile method for cathode material fabrication. With a working gas of air, ionized gas catalyzed immediate reaction to form cathode precursors from metal salts. This commercializable synthesis method provides a solution to the excessive time and energy waste as well as the environmental and health hazards which are inherent in the coprecipitation manufacturing method that dominates the current NMC production market. In this work, high capacity NMC compositions are produced using the plasma fabrication method. Method produced desired “meat-ball” particle morphology of secondary particles up to ~20μm made up of primary particles ≤1μm.Ni rich Ni-Mn-Co (NMC) cathode materials were characterized for their lithium-ion capacity. Specifically, pristine cathode material with 955 and 811 compositions were prepared and tested using coin cells. Li-NMC with 955 (90% Ni; 5% Mn; 5% Co) cycled with initial specific capacity of 215 mAhg-1, with coulombic efficiency 99% at 20 cycles. Similarly, Li-NMC with 811 composition (80% Ni, 10% Mn and 10% Co) exhibited 190 mAhg-1 capacity and coulombic efficiency >99% over 20 cycles. Cyclic voltammetry confirmed three expected phase changes upon lithiation and delithiation, with clear durability and reversibility after first cycle. Layered crystal structure is confirmed with highly desired particle morphology for best packing density. NMC particles as synthesized by the atmospheric plasma method exhibit baseline NMC performance characteristics. [1] Vanessa Pimenta, M.S., Dmitry Batuk, Artem M. Abakumov, Domitille Giaume, Sophie Cassaignon, Dominique Larcher, and Jean-Marie Tarascon, Synthesis of Li-Rich NMC: A Comprehensive Study. Chemistry of Materials, 2017. 29: p. 9923-9936. [2]Monu Malik, K.H.C., and Gisele Azimi, Effect of Synthesis Method on the Electrochemical Performance of LiNixMnCo1-x-yO2 (NMC) Cathode for Li-Ion Batteries: A Review. Rare Earth Metal Technology 2021, 2021. [3]Dong Ren, Y.S., Yao Yang, Luxi Shen, Barnaby D.A. Levin, Yingchao Yu, David A. Muller, and Héctor D. Abruña, Systematic Optimization of Battery Materials: Key Parameter Optimization for the Scalable Synthesis of Uniform, High-Energy, and High Stability LiNi0.6Mn0.2Co0.2O2 Cathode Material for Lithium- Ion Batteries. ACS Applied Materials & Interfaces, 2017. 9: p. 35811-35819. [4]Feng Wu, N.L., Lai Chen, Ning Li, Jinyang Dong, Yun Lu, Guoqiang Tan, Mingzhe Xu, Duanyun Cao, Yafei Liu, Yanbin Chen, Yuefeng Su, The nature of irreversible phase transformation propagation in nickelrich layered cathode for lithium-ion batteries. Journal of Energy Chemistry, 2021. 62: p. 351-358. [5]Ya-Ting Tsai, C.-Y.W., Jenq-Gong Duh Synthesis of Ni-rich NMC cathode material by re dox-assiste d deposition method for lithium ion batteries. Electrochimica Acta, 2021. 381. [6]Fengxia Xin, H.Z., Xiaobo Chen, Mateusz Zuba, Natasha Chernova, Guangwen Zhou, and M. Stanley Whittingham, Li−Nb−O Coating/Substitution Enhances the Electrochemical Performance of the LiNi0.8Mn0.1Co0.1O2 (NMC 811) Cathode. ACS Applied Materials & Interfaces, 2019. 11: p. 34889-34894. Figure 1

In-Situ Formation of Low-Strain and Defect-Free Single Crystal NMC in Electrode Slurries

Synthesis of cathode materials for lithium-ion batteries usually results in agglomerations of single crystals.[1][2] Jet milling is commonly used in industry to deagglomerate cathode material powders.[3] However, dry grinding techniques can often lead to the introduction of defects, requiring a reheating step to reform pristine NMC. Wet milling in water has also been proposed, however, this results in lithium loss and crystal defects, again requiring additional drying and reheating steps are required to reform pristine NMC.[4][5] Here we report a low-strain and defect-free NMC deagglomeration method that is performed in-situ during the electrode slurry dispersion process. In this method, cathode material, conductive additive and binder are planetary milled in N-methyl-2-pyrrolidone (NMP). This results in both the deagglomeration of cathode secondary particles and the formation of a well-dispersed electrode slurry. Figure 1(a-d) compares the SEM images of NMC samples deagglomerated by different dry grinding techniques and the in-situ slurry milling method. Figure 1(e) and (f) show lattice strains and the first cycle voltage curves of the same samples. In comparison to the dry grinding techniques, in-situ slurry milling was found to be more effective in secondary particle deagglomeration than dry methods and resulted in a single crystal NMC with the lowest lattice strain, lowest irreversible capacity, and highest coulombic efficiency. In fact, in-situ milling was found to reduce lattice strain compared to the original agglomerated cathode material, by relieving internal strains created at the grain boundaries of secondary particles. We believe that in-situ slurry milling is an effective method for NMC particle deagglomeration and improving NMC performance.

Unraveling the Synthesis of Positive Electrodes for Na-Ion Batteries by in Situ XRD

In situ diffraction studies can capture transient crystalline phases forming during chemical reactions. Whether the reaction is a chemical solid-state synthesis, or an electrochemical intercalation process within typical active compounds used as battery electrodes, proper sample environments allow nowadays to perform in situ diffraction experiments with high temporal and angular resolution even when using laboratory diffractometers. In both cases, the time-resolved nature of the experiments allows to obtain a greatly increased amount of information. For example, in the synthesis of inorganic materials, reactions often yield non-equilibrium kinetic byproducts instead of the thermodynamic equilibrium phase [1]. On the other hand, often stable compounds cannot be synthesized. To rationalize that, the competition between thermodynamics and kinetics occurring during the process need to be investigated in real time. Fully determining the reaction pathway is a key requirement to achieve the rational synthesis of target materials [2, 3]. In this presentation, recent unpublished examples will be reported from our work applying in situ XRD to understand the synthesis of cathode materials for Na-ion batteries. We focus on layered materials and on the relationship between P2 and P3 polymorphs in series of samples of the same composition NaxDyNizMn1-y-zO2 (where D is a substitutional element and Ni and Mn are in divalent and tetravalent oxidation state, respectively) and highlight the transformation of a phase into the other during calcination. Moreover, we provide electrochemical and morphologic characterizations of the target compounds, aiming to answer the question: does one or the other polymorph offer better performances? The charge compensation mechanism, involving Ni redox but also O redox, will be reported. Finally, the presentation will also briefly cover the investigation of novel solid-state synthesis routes for cathodes of the fluorophosphate Na3V2(PO4)2F3-xOx family.

Solution-Based Synthesis of Cathode Materials for Lithium Ion Batteries

Electrochemical energy storage is expected to make an important contribution to combating global climate change, e.g. via electric vehicles and stationary storage. Currently, lithium-ion batteries are the most prominent candidate for rechargeable batteries to be used in this respect. However, performance of lithium-ion batteries is strongly influenced by the active material at the cathode side, which is often a complex multi-metal oxide. Such a material's properties are dictated by the fabrication method. The design of an appropriate synthesis strategy is then logically also aimed at optimal material properties. However, the design strategy should also take into account green chemistry principles, such as atom economy and energy efficiency. Solution-based routes towards (multi)metal oxide synthesis provide a large diversity of routes and therefore a strong versatility in their design. In this contribution, two groups of routes will be discussed: aqueous solution-gel and coprecipitation routes. The aqueous solution-gel route encompasses three stages: precursor solution synthesis, in which the metal ions are stabilized by complexation with carboxylate ligands, gelation to form an amorphous precursor gel in which the metal ions are homogeneously mixed, and decomposition into the final metal oxide. In this route, precipitation is to be avoided, since it would introduce inhomogeneities. In contrast, the coprecipitation route is entirely based on the formation of insoluble solid precipitates, which can be further transformed in a solid state reaction into lithiated compounds. Whereas solution-gel is ideally suited for complex metal oxides with a large number of metal ions, coprecipitation of many different metal ions at the same time can be challenging. On the other hand, the atom efficiency of the latter can be very high which is attractive for upscaling. Certainly, both of these routes have a high versatility because of the flexibility in compositions (starting products, solvents, ...) and conditions (temperature, time, ...) during the synthesis.In this presentation, an overview will be given of the application of these synthesis routes to the synthesis and/ or surface modification of various cathode materials for lithium ion batteries, which are of general interest and are ranging from Ni-rich compositions of NMC (NMC622), to lithium manganese rich NMC and to Co-free compositions such as LNMO and Li rich LMO. First, the classic NMC 622 is surface modified by a TiOx via a sol-gel route, leading to the formation of core-shell structured particles. The presence of TiOx improved the rate performance and electronic conductivity of the cathode material, and led to a higher initial coulombic efficiency and lower ageing rates in full cells with LTO. Furthermore, layered Li-rich/Mn-rich (LMR-)NMC, which is interesting because of its remarkably high specific discharge capacity was synthesized by two different routes, solution-gel and coprecipitation. It was shown that the solution-gel material in this case had a retarded voltage fade but larger capacity fade than the coprecipitated material. This was correlated to differences in particle morphology and the presence of Ni-enriched spinel-type surface layer. Furthermore, the effect of Sn4+ substitution in the LMR-NMC was investigated. The solubility of Sn4+ substituting for Mn4+ turned out to be a limiting factor here, and could not prevent the voltage fade sufficiently. Finally, we turned to Co-free cathode compositions. LiNi0.5Mn1.5O4-delta was prepared by an aqueous solution-gel route, which allowed to tune the particle size (a few µm versus 70 µm) and morphology. This led to optimized initial discharge capacity and its retention. Finally, Ti4+ substituted Li2MnO3 was synthesized as well via an aqueous solution-gel method. The substitution was shown to improve the structural stability, and galvanostatic cycling hinted at a delayed oxygen release during the first 10 cycles, however, followed by pronounced oxygen redox activity.In conclusion, solution-based routes are highly versatile and provide many opportunities to synthesize cathode materials for lithium ion batteries.

Multi-component precursor droplet evaporation in spray synthesis of cathode materials

Spray synthesis methods are highly attractive for manufacturing materials for energy storage and conversion owing to their scalability and controllability. The key to achieving high controllability in spray synthesis is understanding the complex relationship between the precursor spray droplet evaporation process and the final product structure. Although several studies on precursor droplet evaporation have been reported, very few consider multi-component droplets, which are relevant in practical applications. In this study, we analysed the evaporation of multi-component single precursor droplets used in flame-assisted spray pyrolysis (FASP) of Li(Ni0.8Co0.1Mn0.1)O2 (NCM811) cathode materials. The product particles of FASP were characterized using SEM, EDS and EELS to determine the structure and morphology of particles obtained from precursors with and without urea additives. The qualitative and quantitative changes during evaporation were analysed using high-speed visualization of suspended single droplets on cross-wires. An in-house developed numerical model was used to track the trajectory of the solutes within the evaporating droplet and elucidate the connection between the evaporation process and the final product structure. It was found that evaporating droplets with multiple precursor solutes (Li, Ni, Co, and Mn) formed product particles with gradient element distribution in the radial direction. However, the addition of a small amount of urea (2.5 wt%) caused significant disturbances in the droplet evaporation process triggered by the urea decomposition reaction leading to uniformly distributed elements in the final product particle. The study contributes towards enhancing fundamental knowledge on multi-component droplet evaporation leading to improved design of spray drying and synthesis processes.

Recovery of Nickel from Recycled NiO by Acid Leaching

The work done here deals with the extraction of Nickel from the recycled NiO material. The as such material characterized by ICP showed Nickel content of 75.14% along with other major metals such as Ca, Mg, Al, Co, and Fe. Different factors were studied affecting the efficiency of the Nickel extraction such as type of acid, organic (Citric acid) and inorganic (H2SO4), concentration of acid, temperature, stirring rate and solid liquid ratio using 2-level 1/4th factorial experimental design. The results showed that between two types of acids, Nickel leaching is higher in Inorganic acid system (H2SO4). Furthermore, for H2SO4 acid system S/L ratio is the most effective parameter for Ni extraction. Whereas acid concentration affects more for Fe/Ni selectivity. The importance of this study is in the Li-ion battery sector where Nickel is the vital element used in the cathode material synthesis.

Direct Solution-calcination synthesis of residual Li-free layered cathode materials for Li-ion batteries

Layered cathode materials have advanced existing Li-ion batteries by improving cell voltage and enabling facile charge transfer. Yet diverse synthetic issues such as particle inhomogeneity, Li residues, complicated processes, and large micron-scale particle sizes, need to be addressed. We report a direct solution-calcination strategy for the simple and scalable synthesis of layered cathode materials (i.e. LiCoO2) for Li-ion batteries. Polyvinylpyrrolidone (PVP) as functional agent is introduced to intimately bind and uniformize the metal precursors, thereby sufficiently eliminating surface Li residues and forming a uniform particle distribution. Compared with commercial LCO, solution-calcined LCO exhibits improved cycling stability and rate capability with suppressed phase transition. The structural phase evolution mechanism for solution-calcination is investigated using in-situ X-ray diffraction analysis. Overall, our research suggests a simple and versatile strategy for the synthesis of cathode materials; the proposed method is effective and avoids complicated synthesis steps and the formation of unwanted residual lithium compounds.

High Value-Added Utilization of Waste Hydrodesulfurization Catalysts: Low-Cost Synthesis of Cathode Materials for Lithium-Ion Batteries

This work introduces a one-step method for the preparation of layered oxide cathode materials utilizing pure Ni and Co mixed solution obtained from the waste hydrodesulfurization (HDS) catalyst. An efficient non-separation strategy with pyrometallurgical-hydrometallurgical (pyro-hydrometallurgical) process consisting of roasting and leaching is proposed. Most of the impurity metal elements such as Mo and V were removed by simple water leaching after the waste HDS catalyst was roasted with Na2CO3 at 650 °C for 2.5 h. Additionally, 93.9% Ni and 100.0% Co were recovered by H2SO4 leaching at 90 °C for 2.5 h. Then, LiNi0.533Co0.193Mn0.260V0.003Fe0.007Al0.004O2 (C–NCM) was successfully synthesized by hydroxide co-precipitation and high temperature solid phase methods using the above Ni and Co mixed solution. The final C–NCM material exhibits excellent electrochemical performance with a discharge specific capacity of 199.1 mAh g−1 at 0.1 C and a cycle retention rate of 79.7% after 200 cycles at 1 C. This novel process for the synthesis of cathode material can significantly improve production efficiency and realize the high added-value utilization of metal resources in a waste catalyst.

Ultrafast Non-Equilibrium Synthesis of Cathode Materials for Li-Ion Batteries.

The synthesis of cathode materials plays an important role in determining the production efficiency, cost, and performance of lithium-ion batteries. However, conventional synthesis methods always experience a slow heating rate and involve a complicated multistep reaction process and sluggish reaction dynamics, leading to high energy and long time consumption. Herein, a high-temperature shock (HTS) strategy is reported for the ultrafast synthesis of cathode materials in seconds. The HTS process experiences an ultrahigh heating rate, leading to a non-equilibrium reaction and fast reaction kinetics, and avoids high energy and long time consumption. Mainstream cathode materials (such as LiMn2 O4 , LiCoO2 , LiFePO4 , and Li-rich layered oxide/NiO heterostructured material) are successfully synthesized with pure phases, oxygen vacancies, ultrasmall particle sizes, and good electrochemical performance. The HTS process not only provides an efficient synthesis approach for cathode materials, but also can be extended beyond lithium-ion batteries.

Preliminary Study of LiCoPO4 cathode material synthesis for LiCoPO4/Graphite Cell

<p>Nowadays, the race towards a high-performance Li-ion batteries discovery for energy storage has become an interesting technological challenge. New or improved Li-ion battery cathodes have been developed relentlessly in this decade. LiCoPO<sub>4</sub> (LCP) is a cathode material that allow a battery to operate at high voltage which resulted a high energy density battery. The presence of strong P-O bond adds a thermal stability feature to LIB cells. In this study, a LiCoPO<sub>4</sub> material were prepared by precipitation of Co<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub> (CP) followed by high temperature Li insertion. H­<sub>3</sub>PO<sub>4</sub> were used as the phosphate source. The crystallization or precipitation of CP can only be achieved under mild pH condition, which can be controlled using sodium hydroxide. XRD, SEM and FTIR analysis were used to characterize the final product. The as-obtained LCP were applied as cathode material while graphite was used as the counter anode. The cell can deliver a charge-discharge capacity at a voltage of 2.0-4.95 V. This preliminary can be a groundwork toward the commercialization of LCP based Li-ion batteries for high duty application.</p>

Influence of sintering temperature on the electrochemical properties of P2-type Na0.67Mn0.7Ni0.2Mg0.1O2 cathodes for sodium-ion batteries

Sodium-ion batteries are thought to be ideal alternatives to Lithium-ion batteries due to their similar electrochemical properties. However, several technique obstacles in cathode materials still impede the commercialized adoption of Sodium-ion batteries. Herein, the Mg-doping P2-type Na0.67Mn0.7Ni0.2Mg0.1O2 cathode materials were synthesized via a two-step process, including sol-gels and solid-state reaction method. This paper pays much attention to the optimal calcination temperature in the synthesis procedure and its effects are subsequently investigated. According to the results, under a series of calcination temperatures from 800 to 950 ​°C, Na0.67Mn0.7Ni0.2Mg0.1O2 cathode materials shows different particle sizes and crystalline structures, exhibiting varied electrochemical properties. Among them, samples calcinated at 900 ​°C display a high specific discharge capacity of 120.9 ​mAh g−1, and a stable cycling performance of 67.2% retention at 1 C rate for 100 cycles. The results suggest that calcination temperature at approximately 900 ​°C could effectively promote the electrochemical performance, which provides a good reference for the synthesis of cathode materials in sodium-ion batteries.

Ti3C2 MXene with pillared structure for hybrid magnesium-lithium batteries cathode material with long cycle life and high rate capability

Cationic surfactants (CS) pillared Ti3C2 composites (Ti3C2/CS) were prepared by a facile electrostatic assembly method, which have large interlayer spacing and slight N-doping. In hybrid magnesium-lithium batteries (HMLBs), the Ti3C2/CS composites exhibit excellent performance by utilizing both Li+ and Mg2+ as charge carriers. Among these composites, the Ti3C2/CTAB (CTC) electrode displays a reversible capacity of 115.9 and 60 mAh g−1 in APC/LiCl (APCL) and APC electrolytes at 0.1 A g−1, and it also exhibits excellent high rate performance and ultralong cycle performance. It is verified that CS is vital to significantly improve the diffusion kinetics of Mg2+ on the electrode surface. The CS can act as the conductive “bridge” which connects different Ti3C2 layers and the interlayer pillar which expands the interlayer distance. In addition, the N element in CS is effective in neutralizing electronegativity and enhancing electrical conductivity for the CTC electrode. The electrode design strategy can adapt to the synthesis of cathode materials with high rate capability in HMLBs.

Synthesis of cathode material with different dosage of maleic acid-leachate of spent lithium-ion batteries

In this paper, LiNi1/3Co1/3Mn1/3O2 cathode materials were synthesized by sol-gel with different dosage of maleic acid-leachate of spent lithium ion batteries (LIBs). Electrochemical performance test was performed on the re-synthesised materials to explore the effect of leachate dosage. The results show that the degree of Li+/Ni2+ mixing increased while initial discharge capacities and capacity retention decreased significantly with leachate dosage increasing. Therefore, the leachate dosage is preferably 65% which can achieve a win-win situation in economy and performance when the LiNi1/3Co1/3Mn1/3O2 cathode materials were synthesized with maleic acid-leachate of spent LIBs in our work.

Mesoscale-architecture-based crack evolution dictating cycling stability of advanced lithium ion batteries

Abstract The cracking phenomenon of Ni-rich NMC (LiNixMnyCo1−x−yO2, x ≥ 0.6) secondary particles is frequently discovered and believed to be one of critical reasons deteriorating the long-term cycling stability of NMC cathode in lithium ion batteries (LIBs). However, the initiation and evolution of those cracks is still controversial due to the limited quantification especially by in situ monitoring, leading to the challenge of identifying an efficient approach to inhibit the formation of the fractures during repeated cycling. Herein, the irreversible, anisotropic cycling lattice and mesoscale expansion/shrinkage of nano-grains during the first cycle, as revealed by in situ X-ray diffraction (XRD) and in situ atomic force microscopy (AFM), have been quantified and confirmed to be the dominant driving forces of microcracks initiation at the grain boundaries. These microcracks preferentially nucleate at the core region with random oriented nano-grains in early stage. The further growth and aggregation of microcracks into macrocrack eventually results in microfracture propagation radially outward to the periphery region with more uniform nano-grain orientation. This mesoscale nano-grain architecture controlled cracking process highlights the importance of predictive synthesis of cathode materials with controllable multiscale crystalline architecture for high-performance LIBs.

Synthesis and Manipulation of Single-Crystalline Lithium Nickel Manganese Cobalt Oxide Cathodes: A Review of Growth Mechanism.

Lithium nickel manganese cobalt oxide (NMC) cathodes are of great importance for the development of lithium ion batteries with high energy density. Currently, most commercially available NMC products are polycrystalline secondary particles, which are aggregated by anisotropic primary particles. Although the polycrystalline NMC particles have demonstrated large gravimetric capacity and good rate capabilities, the volumetric energy density, cycling stability as well as production adaptability are not satisfactory. Well-dispersed single-crystalline NMC is therefore proposed to be an alternative solution for further development of high-energy-density batteries. Various techniques have been explored to synthesize the single-crystalline NMC product, but the fundamental mechanisms behind these techniques are still fragmented and incoherent. In this manuscript, we start a journey from the fundamental crystal growth theory, compare the crystal growth of NMC among different techniques, and disclose the key factors governing the growth of single-crystalline NMC. We expect that the more generalized growth mechanism drawn from invaluable previous works could enhance the rational design and the synthesis of cathode materials with superior energy density.

Recent Advances in the Rational Design and Synthesis of Two-Dimensional Materials for Multivalent Ion Batteries.

With the increase of device requirements, rechargeable lithium-ion batteries are facing tremendous challenges in large-scale applications due to the high price and gradual shortage of lithium sources. In contrast, multivalent ion batteries, such as aluminum, magnesium, and zinc, are promising candidates for the next-generation energy-storage systems because of their high volumetric energy density, safe operation, and abundant reserves. The strong intercalation between multivalent ions and the host materials, however, will cause lower ion-diffusion kinetics and a poor discharge capacity. One of the main challenges is to search for a suitable cathode material with a high capacity and good structural stability to overcome the abovementioned problems. Two-dimensional layered materials, with characteristic unique structural features, good conductivity, and high electrochemically active surface, have attracted attention from researchers during the past decade. In this review, the design approach and synthetic procedures for the preparation of two-dimensional materials as cathodes for multivalent ion batteries, including interlayer engineering, two-dimensional heterostructures, pore/hole engineering, and heteroatom doping, are summarized. Meanwhile, the relationship between the design configuration and optimized electrochemical performance is rationally and systematically presented. Additionally, perspectives for the sustainable synthesis of cathode materials are proposed for multivalent metal-ion chemistry.

Sucrose-Assisted Solution Combustion Synthesis of Doped Strontium Ferrate Perovskite-Type Electrocatalysts: Primary Role of the Secondary Fuel

The methodologies and experimental conditions used for the synthesis of cathode materials for electrochemical devices strongly influence their electrocatalytic performance. In particular, solution combustion synthesis is a convenient and versatile methodology allowing a fine-tuning of the properties of the material. In this work, we used for the first time a sucrose assisted-solution combustion synthesis for the preparation of Cerium and Cobalt-doped SrFeO3–δ electrocatalysts and we investigated the effect of polyethylene glycol (PEG) addition as a secondary fuel on their structural, microstructural, redox and electrochemical properties. The perovskite-type powders were characterized by X-ray diffraction coupled with Rietveld refinement, scanning, and high-resolution transmission electron microscopies, thermogravimetric analysis, nitrogen adsorption measurements, and temperature-programmed reduction. Electrical conductivity and overpotential measurements were performed after the deposition of the powders onto a Gd-doped ceria electrolyte pellet. Stable high-valence B-site cations were detected in the powders prepared from sucrose-PEG fuel mixtures, although a substantial improvement of the conductivity and a decrease of the overpotential values were obtained only with high molecular weight PEG. The superior electrochemical performance obtained using PEG with high molecular weight has been ascribed to a faster interaction of the powder with the oxygen gas phase favored by the nanometer-sized crystalline domains.