The quest for renewable energy sources is prompting the development of technologies capable of tapping into alternative energy sources such as solar, wind, geothermal and tidal energy. To fully exploit these energy sources, engineers need novel ways of storing and converting these energies.
Lithium-ion batteries are generally the power source of choice for the booming market in portable electronic devices, including smartphones, smartwatches and laptops. These batteries are complex energy storage devices with unique electrochemical characteristics incorporating high-density metals, low-density polymers and other materials.
The benchtop scanning electron microscope (benchtop SEM) is a key analytical tool in investigating materials' mechanical, chemical and electrical properties in batteries, fuel cells, supercapacitors, electrolyzers and heterogeneous catalysts.
Characterization of Energy Storage Devices Using a Benchtop SEM
In electrochemical systems, the critical properties affecting the quality of energy conversion processes are determined by component surfaces and their microscopic properties. The microscopic properties affecting the bulk behaviors of these components are of particular interest to materials scientists.
The efficiency of batteries and fuel cells is governed by the diffusion of ions, the transport of electrons and the chemical interactions of electrode/electrolyte materials. Using a benchtop SEM, engineers can characterize the structure and properties of components that shed light on their behavior during electrochemical processes. These behaviors may include ion relocation, lattice expansion or contraction, phase transition and surface reconstruction.
In batteries, the charging and discharging processes involve the transfer of ions through an electrolyte and the interfaces between an electrode and an electrolyte. Improving the performance of batteries requires the design of electrode materials with adequate energy density and efficiently designed electrode and electrolyte configurations.
Supercapacitors store and release energy through the accumulation and dissipation of charges at solid-liquid interfaces. To improve their performance, engineers need to design efficient interfacial structures that increase charge density (capacity) and enhance the transfer of cations and anions (power density).
Fuel cells convert chemical energy into electrical energy by oxidizing fuels such as hydrogen and alcohols. To enhance the kinetics of catalysts, engineers need to optimize their surface composition and structure.
For heterogeneous thermal catalysts, engineers seek to control the molecular structures of catalysts and enhance support-catalyst interactions.
These varied applications present unique challenges to materials scientists. Nonetheless, they all depend on efficient transfers and interaction of particles within materials or their interfaces at nanometer scales. The benchtop SEM is an indispensable tool in the characterization of these processes. Using a benchtop SEM, materials scientists can obtain high-resolution images and perform elemental analysis of materials at nanoscales. A benchtop SEM enables:
- Surface imaging of an electrode
- Imaging cross-sections of electrodes or battery cells
- Grain structure and orientation analysis on surfaces
- Determination of grain boundary losses
- Defect analysis
- Elemental analysis of surfaces
- Chemical phase analysis
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Use Cases of a Benchtop SEM in Energy Storage Applications
Batteries and fuel cells - Lithium-ion batteries are used in portable electronic devices, stationary power sources and electric vehicles. Their performance is determined by energy density, battery capacity, charge and discharge rates and the lifetime of the battery. A benchtop SEM enables the identification of defects and the characterization of nanostructures in lithium-ion batteries.
Cathode analysis - Cathodes undergo electrochemical stresses during lithiation and delithiation. This may lead to grain cracking, changes in pore sizes and contact loss of particles, thus reducing the lifetime of the battery. A benchtop SEM may perform particle orientation and structure analysis to track these defects.
Anode analysis - Similarly to cathodes, anodes undergo electrochemical stresses. However, since they are typically made of graphite, their failure characteristics may be different. A benchtop SEM may help characterize defects in graphite particles that lead to defective ionic transfers, which reduce the lifetime of the battery.
Photovoltaic solar cells - Photovoltaic solar cells are typically manufactured from crystalline silicon. The bulk behavior of these silicons is determined by their crystallinity and crystal sizes. To improve solar cell technology, materials scientists require a detailed understanding of the nanostructures, compositions and electrical properties of these silicons. Again, a benchtop SEM may help characterize these properties.
These are a few examples of the applications facilitated by a benchtop SEM. Materials engineers may find other applications for their benchtop SEM that fulfill specific use case scenarios.
Benchtop SEM from JEOL
The JCM-7000 benchtop SEM from JEOL incorporates advanced functionalities that make it simple for users at any skill level to obtain outstanding images and elemental analysis results in just minutes. It is equipped with real-time 3D imaging, advanced auto functions and the option to add a fully embedded EDS system for real-time compositional analysis.