One basic electrochemical process in lithium ion batteries, the lithiation and delithiation (discharging and charging) of battery materials has until now never been observed at the nanoscale.
Researchers believed that during discharge, the current from the negative to the positive electrode is carried by lithium ions and then charging causes this reaction to reverse by applying an over voltage to the battery.
Nevertheless they have not been successful in creating quantifiable and analytical observations while observing the reaction.
Improvements in Lithium Ion Batteries
Lithium (Li) ion batteries are commonly used in consumer electronics due to the fact that they have high energy density, low standby energy drain, and no memory effect. In recent years, these batteries have seen constant improvements in terms of size, portability, charging times, charge density, and weight.
However, with the market constantly changing, continuous innovation and enhancement is required as consumer electronics evolve into smaller sizes and higher power consumption applications. Moreover, safety concerns regarding Li-ion batteries have created a major focus on comprehending the changes happening at the molecular level.
Figure 1. Charging and discharging of the cathode material LiFePO4 in situ.
The in situ charging and discharging of the cathode material LiFePO4 can be seen in Picture 1. The 5eV spectroscopic EFTEM images of charging and discharging are indicated on a 400nm scale bar. Bright regions are delithiated FePO4 and dark regions are LiFePO4. There are excess bright regions of FePO4 at the end of charge cycles and minimal during the discharges.
So far it has proved challenging to researchers to test the operation of batteries on the nanoscale as electron microscopes were not capable of imaging most electrochemical methods.
The lithiation and delithiation of battery materials can currently be observed in real time, within an electron microscope with the aid of Protochips EFTEM tools.
Powerful Imaging Instrument
The electron microscope is a powerful imaging instrument that can image structures down to the atomic scale. Dr. David Muller's research team at Cornell University used the Poseidon 500 system in the FEI Titan electron microscope to study the lithiation and delithiation of a Li-ion battery.
The loss of efficiency in batteries can be avoided by ensuring that lithium is not trapped within the battery. Dr. David Muller spectroscopically tracked the charging and discharging method within the battery to get a better understanding on the way the lithium moved during the experiment.
Along with the resolving power of the microscope, the Poseidon 500 can be applied for conducting electrochemical experiments.
As the system is designed for liquids, it allows scientists to choose the precise electrolyte needed by the experiment. Battery functionality can then be analysed in real time at the atomic or nanometer scale.
The quantitative data provided via the system, along with the in situ observations resulted in the design of a prototype that clarifies possible mechanisms which activate trapped lithium within a battery.
By further understanding this method, it is possible to develop advanced battery designs and high efficiency batteries that can resist performance loss after usage. Furthermore, spatial distributions decrease coalescence by permitting particles to move a longer distance before hitting another particle.
Li-ion batteries are currently the ideal performing energy storage technology, and are likely to stay the same in the near future. It is important to understand and improve their performance in order to enable them to maintain pace with the needs of electric vehicles, electronic devices, and renewable energy generation.
Protochips, Inc. is a rapidly growing early-stage company focused on providing the world's leading materials and life sciences research breakthrough analytical tools for targeted research and development of nano-scale materials.
Using its proprietary technology, Protochips is addressing the market need by transforming the most widely used tools in nanotechnology – electron and optical microscopes - from cameras into complete nano-scale laboratories.
Protochips' core competency lies in the application of semiconductor techniques to development of MEMS devices capable of providing heat, electrical, liquid and gas environments to samples in situ.
This information has been sourced, reviewed and adapted from materials provided by Protochips.
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