In this interview, Dr. Rosy Sharma, a Post-doctoral Researcher from Bar-Ilan University talks to AZoM about understanding the Electrochemical Behavior of Lithium-ion Batteries
Could you give our readers an overview of Noked Lab and the research you do?
At Noked lab at the Bar-Ilan Institute of Nano Technology and Advanced Studies in Israel, we utilize state of the art deposition techniques for interfacial modification of surfaces by functional thin films.
Primarily, we rationally design the multi-functional interfaces for electrode materials in order to improve battery performance by mitigating material degradation and suppressing the parasitic reaction at the electrode/electrolyte interfaces. We actively apply our surface protection strategies to improve Li-ion, Na-ion, Solid-state, Li-O2, Li-S, and Mg-ion batteries.
In addition to electrochemical energy storage, we are also involved in molecular layer deposition of chiral thin films, antibacterial coatings of biological importance, and designing new surface chemistries.
Why is it so important to understand the electrochemical behavior of Lithium-ion batteries (LIBs)?
Electrochemical power sources and energy storage systems are playing a vital role in shifting the paradigm of the future energy network towards clean, renewable sources. This is because such systems form a vital bridge between dispatchable energy generation and intermittent supply from renewable sources such as wind and solar power.
It is well known that in powering the 3Cs - computers, communication devices and consumer electronics - lithium-ion batteries (LIBs) have deeply penetrated every corner of our daily lives. Despite LIBs’ successful history, including being awarded the Nobel prize, there has been a continuous call to improve their capabilities and performance, primarily driven by their inability to meet society’s emerging needs.
Current LIBs, with a maximum specific energy of ca. 250 Wh kg-1 (at the cell level), do not offer sufficient energy, rate, durability, or affordability to match the performance of traditional automotive gasoline/internal combustion engines.
In addition, detrimental climatic change has hastened the need to electrify transport and develop reliable energy storage systems. These urgent requirements are driving the scientific community to further increase the energy and power density of LIBs.
The energy density of a battery is determined collectively by the specific capacity of electrodes - which is basically a scale for describing how many Li+ (in case of LIB) ions can be stored, and the working voltage of the cell. Thus, significant research initiatives are underway to design a new class of electrode materials possessing high specific energy and/or high operating potential.
Most of these high energy, high voltage electrode materials challenge the stability of the most relevant electrolyte solutions. Also, they suffer from stability problems, plagued by both capacity and average voltage fading during cycling, due to their complex structure and operation mechanism.
The durability and cycle life of LIBs depends on complex interfacial interactions between the electrodes and the electrolyte solution, and the development of passivation phenomena on the electrode surfaces.
In order to control and tune the performance of newly designed electrode materials, investigating their electrochemical behavior is very important, particularly to understand the degradation mechanism, onset potentials of parasitic reactions, diffusion kinetics, etc.
This understanding of electrochemical behavior will provide insight into designing and developing suitable materials for next-generation batteries with high energy density and efficiency in the future.
Could you tell us more about your background in the electrochemical analysis of batteries?
As a post-doctoral researcher under the auspices of the Israel National Research Center for Electrochemical Propulsion and Bar-Ilan University, I explore two main issues: Why batteries fail or perform with less efficiency? and, what we can do to improve battery performance?
Accordingly, I invested efforts in probing the interfacial electrochemistry of rationally designed electrode materials (EMs) with highly reactive surfaces such as Li and Mn-rich or/and Ni-rich NCM compounds.
During my post-doctoral tenure of over 3 years, I demonstrated the dependency of battery durability and cycle life on complex interfacial interactions between the electrodes and the electrolyte solution.
Using atomic layer deposition to design the passivation layer, I succeeded in mitigating structural degradation to a significant extent. With experimental and spectroscopy tools, I showed that a thin surface coating is a key strategy for extending the lifetime of batteries by preventing their degradation through suppression of interfacial reactivity with the electrolyte, and, through inhibition of transition metal ion dissolution and structural deformation.
What are the main applications of your research?
I believe that by addressing the scientific questions and challenges listed above, we will enable the lifetime extension of high voltage, high energy next-generation electrode materials; thereby enabling the realization of improved lithium-ion batteries with superior energy and power densities.
Could you explain to our readers how Online Electrochemical Mass Spectrometry (OEMS) works as an analytical technique?
As the name suggests “Online Electrochemical Mass Spectrometry (OEMS)” is an analytical tool that bridges electrochemical investigations with mass spectroscopy.
OEMS allows the in-operando analysis of volatile species originating/changing during the electrochemical process. The volatile species in the electrochemical cell are sampled through the microcapillary to the ionizer in vacuum. The resulting ions are then segregated based on their mass-to-charge ratio (m/z) through a quadrupole mass analyzer.
OEMS With the microflow capillary, does not require any carrier gas for sampling the reaction products of the electrochemical cell, which endows high sensitivity to even small changes.
The extremely small sampling volume of the micro-capillaries allows us to carry out analysis under realistic conditions without changing the internal environment of the system. This is necessary to understand the cascading reactions happening during the electrochemical process.
How do you use the HPR-40 OEMS for your electrochemical analysis?
In our laboratory, we employ HPR-40 OEMS for in-operando investigation of evolving gases, in real-time coordinates of battery cycling. The unique micro-capillaries sample the volatile intermediates and reaction products produced inside the battery during the application of current and voltage without any significant time delay.
By studying the variation of the desired charge to mass ratio during the electrochemical process, we interpret the degradation mechanistic and the onset potential of the parasitic process.
The insights provided by OEMS enable us to characterize the governing surface reaction and instabilities by analyzing the gases and help us decide the potential window for the electrochemical characterization.
What can you do with the HPR-40 OEMS that wasn't possible before?
With OEMS, we can investigate the efficacy of our surface protection strategies in limiting the parasitic reactions. By performing a comparative analysis of the gaseous evolution originating from the oxidative decomposition of either/both electrolyte and electrode material (surface treated and untreated) as a function of applied voltage, we conclude the role of surface coatings in protecting the electrode material against the oxidative/reductive or chemical damage.
This in-operando information is crucial in determining the effectiveness of thin protection films which can only be obtained through OEMS.
What do you see as the future of electrochemical analysis, and the analysis of Lithium-ion batteries in general?
In the future, I believe the progression of science and the curiosity of researchers to understand the complicated interfacial behavior of batteries will lead to the development of electrochemical analysis coupled with spectroscopic and microscopic tools to track the real-time evolution of battery materials with applied voltage/current. This will be the point at which we can actually understand the complicated science of batteries.
About Dr. Rosy Shamra
Dr. Rosy works as a post-doctoral researcher at Bar-Ilan University, Israel. Her research aims to optimize and apply atomic layer deposition for the surface engineering of electrode materials in order to improve battery performance.
In association with the Israel National Center for Electrochemical Propulsion, she is responsible for analyzing evolved gases during battery performance using online electrochemical mass spectroscopy (OEMS), for the group of Prof. Doron Aurbach and Dr. Malachi Noked.
She was educated as an electrochemist/analyst at the Indian Institute of Technology Roorkee, India, where she was awarded a Ph.D. Degree in 2017. Since then, she has received prestigious fellowships like a Colman Soref (Bar-Ilan Institute Excellence fellowship), and a PBC fellowship for an outstanding post-doctoral researcher (awarded by Israel Ministry of Higher Education).
This information has been sourced, reviewed and adapted from materials provided by Hiden Analytical.
For more information on this source, please visit Hiden Analytical.
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