in recent yearsThe pursuit of "clean emissions" by various countries has led to the rapid development of new energy vehicles, which in turn has driven the rapid development of lithium-ion batteries.The 2019 Nobel Prize in Chemistry was awarded to three scientists engaged in research on lithium-ion batteries - American scientist John Goodenough, British American scientist Stanley Whittingham, and Japanese scientist Akira Yoshino.

The current power lithium-ion batteries contain various key materials, whether cylindrical, square or soft pack batteries, their structural composition is similar to the following figure. Positive electrode materials account for a relatively high proportion in both cost and analysis items.

According to the different materials, lithium-ion batteries can be divided into lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, nickel cobalt manganese (ternary) type, etc. Currently, commercially available power lithium batteries are mainly lithium iron phosphate and ternary.

This series will comprehensively analyze Shimadzu's complete solution and characteristic applications from five dimensions: positive and negative electrodes, isolation film, electrolyte detection, and failure analysis of battery cells in power lithium batteries.

A complete solution for positive electrode materials

Shimadzu has a variety of characterization and testing equipment that can assist positive electrode material and battery companies in meeting various production, quality control, and research and development testing needs.

featured applications

1. Detection of aggregates and foreign objects

Positive electrode material, whether it is lithium iron phosphate orNCM, NCA and other ternary materials inevitably contain aggregates or foreign objects in the production process of material enterprises or the use process of battery enterprises. The presence of these foreign objects may pose significant potential hazards to the performance and safety of subsequent batteries. There are various methods for detecting foreign objects, but whether it is electron microscopy or other methods such as X-ray, they all have the disadvantage of high cost and inability to adapt well to the ever-changing production environment.

Shimazu is hereThe new product launched in 2019, the iSpect DIA-10 dynamic particle image analysis system, has low usage and maintenance costs, high instrument sensitivity, and simple and convenient operation. It also has the characteristics of being sturdy and durable, especially suitable for testing aggregates, foreign objects, and other analysis of ternary positive electrode materials on production lines.

2. Detection of element content and characterization of its distribution

Electron probe microanalyzerEPMA, as an effective analytical tool, is widely used in the research and development of various materials for lithium-ion batteries, quality management of manufacturing processes, and defect analysis. Shimadzu's electron probe microanalyzer EPMA-8050G has the characteristics of high spatial resolution, high sensitivity, and high resolution, especially with excellent detection ability for ultra lightweight numerical elements (as low as 4Be). These outstanding features have gained recognition from numerous manufacturers of positive electrode materials. The following case uses EPMA-8050G to characterize the distribution of active materials, binders, conductive additives, and electrolytes in the positive electrode cross-section.

Element surface analysis of the overall positive electrode cross-section

（Al: current collector; Mn+O: active substance; F+P: electrolyte supporting salt; C+F: Adhesive; C: Conductive additives)

Elemental surface analysis of active material after amplification of positive electrode cross-section

3. Evaluation of the relationship between compressive strength and performance of particulate matter

The current positive electrode materials, whether they are lithium iron phosphate orThe mainstream method for NCM/NCA ternary materials is high-temperature solid-state synthesis. In order to achieve better performance, generally speaking, positive electrode materials have porous structures. But porosity also needs to be controlled, otherwise it will cause the material structure to become too loose and easily collapse during charge and discharge cycles.

Shimadzu's miniature compression testing machine（MCT can be used to test the compressive and rebound mechanical properties of individual particles. In addition, the instrument can be equipped with resistance measurement components and temperature control systems, so in addition to obtaining the mechanical properties of particles, it can also simultaneously obtain rich information such as the resistance compression ratio relationship and temperature compression ratio relationship of particles. By combining BET, SEM, laser particle size analyzer and other methods, the obtained positive electrode material particles can have better performance and stability.