The Lithium Ion Battery Advantage
Since their introduction into the commercial market in 1991, lithium (Li) ion batteries have remained one of the most widely used electrochemical power sources for a number of important applications. Li batteries are used to provide energy for smartphones, cameras, tablets, laptops, various storage devices, as well as a number of recently developed electric vehicles (EVs). The successful utilization of Li batteries for these applications is dependent upon the high specific energy, energy density and cycling stability of this energy storage system. For most cathode materials, three different types of lithium metal oxides and phosphates are used, of which are classified as 1-dimensional, 2-dimensional and 3-dimensional Li ion conducting materials.
Unfortunately, the components of Li ion batteries are often susceptible to degradation as a result of the different aging mechanisms associated with the various components of each Li ion battery. While certain degradation processes can be beneficial for the battery’s energy storage potential, such as improved performance, Li ion batteries often exhibit a limited cycle and calendar life as a result of these decomposition processes.
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Previous Lithium Ion Battery Analytical Techniques
Despite their useful application in a number of consumer products, the aging effects associated with Li ion batteries limits their practicality in EVs and other large-scale industrial machinery. These aging effects that can cause harmful degradation to Li in batteries have encouraged research in developing the best analytical technique to assess Li ion battery composition. Some successful analytical methodologies that have been used to assess Li ion batteries include:
- X-ray Photoelectron Spectroscopy (XPS)
- X-ray Diffraction (XRD)
- Energy Dispersive X-ray Spectroscopy (EDX)
While these techniques have been useful, there remains no standard technique that is utilized to fully quantify the aging of Li ion batteries.
Evaluating Transition Metal Dissolution in Li Ion Batteries
One analytical technique utilized to evaluate the elemental properties of Li ion batteries involves measuring the transition metal dissolution (TMD) and its subsequent effects in the battery. The dissolution of transition metals from the cathode of Li ion batteries that eventually leads to their deposition onto the anode is a known contributor to diminished capacity of the battery. Several elemental analysis techniques have been employed to evaluate TMD on Li ion batteries, of which include:
- Total Reflection X-ray Fluorescence + High Sensitivity Fluorescence XAFS using a multi-element solid-state detector (SSD): This method was employed as a result of the limited manganese detection of convention XAFS.
- ICP Analysis: This method was utilized to assess the composition of lithium metal oxides and the dissolution of cobalt, nickel and manganese, however a lack of the specificity of how this technique was utilized limits its future application.
- Atomic Absorption Spectroscopy (AAS): Substances that were deposited onto the electrode of the Li ion battery as a result of TMD have been analyzed by AAS.
- Secondary Ion Mass Spectroscopy (SIMS): SIMS has been used to evaluate the accumulation of manganese on Li ion anodes.
- ICP-OES + Soft X-ray Absorption Spectroscopy
- Inductively Coupled Plasma-Atomic Absorption Spectroscopy (ICP-AAS): This analytical method has been utilized to evaluate the deposition of Mn on Li ion battery anodes and its ability to affect the total capacity of the battery.
Concluding Remarks on Li Ion Battery Elemental Analysis Techniques
While several different methods have been employed to evaluate the local elemental distribution of metals on the anode as a result of dissolution and/or deposition processes, these techniques are often limited in their range of detection and accurate quantification to fully evaluate these effects. As interest in applying Li ion batteries to more and more consumer products continues to rise, there is an urgent need to develop accurate techniques to analyze the composition, reactions, degradation and aging processes that occur within Li ion batteries before, after and during their use in such applications.
References:
- “Elemental Analysis of Lithium Ion Batteries” S. Nowak & M. Winter. Journal of Analytical Atomic Spectroscopy. (2017). DOI: 10.1039/c7ja00073a.
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