一般財団法人材料科学技術振興財団　MST List of Products and Services

The electrolyte of lithium-ion secondary batteries can be qualitatively and quantitatively analyzed using GC/MS. In the example below, ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were identified as organic solvents, and vinylene carbonate (VC) was identified as an additive. It is also possible to determine the composition ratio of the solvents and the content of the additives. Additionally, other additives such as fluoroethylene carbonate (FEC) and ethylene sulfite (ES) can also be evaluated.

The characteristics and reliability of lithium-ion secondary batteries are greatly influenced by materials, among which the impact of the electrolyte is said to be significant. Commercial products in various shapes, such as cylindrical and laminated types, can have their electrolytes extracted using appropriate methods, allowing for the identification of organic solvents and additives. The following case involves extracts from prismatic batteries, confirming the use of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) as organic solvents, and fluoroethylene carbonate (FEC) as an additive.

The separator, which is a key component material of batteries, influences the characteristics and safety of the battery due to its porosity, shape, and other factors. Currently, mainstream polymer materials such as polyethylene (PE), polypropylene (PP), or their composite materials have low softening points, with PE being around 125°C and PP around 155°C. We will introduce a case where the structure of a PP separator with a low softening point was observed, and cooling was performed during cross-section processing to suppress degradation for evaluation.

High-resolution HAADF-STEM images reflect the atomic arrangement of crystals, and by simulating STEM images corresponding to various crystal orientations, they help in accurately understanding the relative orientations between crystal grains and the observed images in polycrystalline materials. This document presents a case where STEM images were simulated from the crystal orientation information obtained by the EBSD method for the crystal grains in a polycrystalline neodymium magnet, and compares them with actual high-resolution HAADF-STEM images.

This document presents a case study of Rietveld analysis applied to the powder X-ray diffraction data of Li(Ni, Mn, Co)O2, which is used as a positive electrode active material in lithium-ion secondary batteries. By seeking a crystal structure model that reproduces the measured powder X-ray diffraction data through simulation, it is possible to precisely calculate crystal structure parameters such as lattice constants, site occupancy rates, and the proportion of cation mixing, which can then be used to discuss the material properties.

The electrolyte used in lithium-ion batteries is generally composed of a solvent and an electrolyte salt, and is considered a homogeneous system on a macroscopic scale. However, from a microscopic perspective, phenomena such as solvation occur. Understanding the local structure of lithium-ion solvation and the reactions that occur when inserting into the positive and negative electrodes is important for the design of high-performance battery materials. This document presents a case study that evaluates the microscopic structure of lithium-ion solvation in the electrolyte of lithium-ion batteries using molecular dynamics simulations.

The segregation of components and the formation of films on the surface of the positive electrode of lithium-ion secondary batteries are factors that influence the electric capacity. We will introduce a case study on Li(NiCoMn)O2 (NCM), which is used as a positive electrode, where micro-region mapping was conducted using AES, and qualitative analysis of organic components (binder) and active material surface films was performed using XPS and TOF-SIMS. These methods allow for analysis with a series of treatments conducted under an Ar atmosphere, which helps to suppress the alteration of the sample.

In lithium-ion secondary batteries, Li(NiCoMn)O2 (NCM) used as the positive electrode can achieve higher capacity by increasing the Ni ratio, and it also excels in high-temperature storage, making it suitable for mass production for automotive applications. On the other hand, cation mixing, where Ni ions occupy Li sites, is considered one of the factors contributing to the degradation of secondary batteries. This presentation will introduce a case where the metal content of the positive electrode active material was evaluated using ICP-MS, the crystal structure was assessed using XRD, and the results were used to perform Rietveld analysis to evaluate the proportion of cation mixing.

Next-generation all-solid-state batteries, which are lithium-ion batteries, are expected to have high safety, high energy density, high output, and a wide operating temperature range. In recent years, research and development aimed at practical application has been actively conducted, but there are various development challenges. At MST, we propose evaluation content suitable for solving development challenges based on comprehensive analysis and evaluation of structure, composition, and electrical properties. This document introduces specific examples of development challenges for all-solid-state batteries, their evaluation content, and representative evaluation methods for each component.

The binder for lithium-ion secondary batteries not only serves as an adhesive between active materials but also needs to be insoluble in the electrolyte. Therefore, the selection of suitable materials for both the positive and negative electrodes is crucial. This document presents cases where the components of the binders used in each electrode sheet were identified by measuring the positive electrode binder using TOF-SIMS and the negative electrode binder using GC/MS, and then comparing the results with a materials library database.

In the electrolyte of lithium-ion secondary batteries, a combination of high dielectric constant solvents and low viscosity solvents is used to improve electrical conductivity. Additionally, additives and electrolytes (supporting salts) not only facilitate the transport of Li ions but also have the function of forming a film on the electrode surface, requiring various performance characteristics. This paper presents examples of qualitative and quantitative analysis of various components such as solvents, electrolytes, and additives by evaluating the electrolyte itself using ICP-MS, volatile components during electrolyte heating using GC/MS, and the dry residue of the electrolyte using TOF-SIMS.

The separator in lithium-ion secondary batteries not only serves the role of isolating the positive and negative electrodes to prevent internal short circuits, but in automotive batteries, it is also required to have heat resistance to prevent a decrease in strength or melting even in high-temperature environments. This report introduces a case study on separators used in overseas automotive batteries, where heat resistance and thermal decomposition behavior were investigated using TG-DTA, and structural and compositional evaluations were conducted using SEM-EDX, FT-IR, XPS, TOF-SIMS, and XRD. It was found that the separator used in the battery consists of a porous polyethylene and a layered structure of polygonal AlO(OH) aimed at heat resistance.

The charge and discharge characteristics of lithium-ion secondary batteries are influenced by electronic conductivity. I will introduce a case where the decreased conductivity of active materials, due to degradation or blockage of conduction paths, was visualized as a resistance value distribution using SSRM. By comparing the results obtained from SSRM with the elemental distribution of Li and other elements measured by TOF-SIMS, it is possible to confirm the correlation between resistance values and elemental distribution. Additionally, it is feasible to classify conductive additives and binders based on resistance values, perform statistical processing, and quantify the mixing degree for each material.

This article introduces a case study evaluating the surface morphology, cross-sectional structure, components, composition, crystal structure, and resistance value distribution of Li(NiCoMn)O2 (NCM), which is used as a positive electrode in lithium-ion secondary batteries. Based on a comprehensive evaluation of structure, composition, and electrical properties, MST proposes assessments suitable for solving development challenges aimed at improving characteristics and enhancing reliability.

We have launched a new service using XPS/HAXPES starting in June! For increasingly complex materials and fine structure samples, we can evaluate the composition and chemical bonding states from the surface to the interior of the material (up to ~30nm) at the same location and in a non-destructive manner. - Depending on the elements of interest and the analysis area and depth, we can select the appropriate X-ray source (Al Kα/Mg Kα/Ga Kα/Cr Kα) to achieve evaluation under suitable measurement conditions. - Non-exposure measurements to the atmosphere, Ar monomer/GCIB sputter etching, and heating pretreatment can be combined. - It is possible to evaluate the electronic states of semiconductor samples using UPS/LEIPS (ionization potential/electron affinity/band gap).