Lithium (Li) is the active ingredient in rechargeable batteries that power today’s smartphones, laptops and electric vehicles. However, the scarcity and high price of lithium led researchers to search for another, more abundant element to replace it. Many have turned to sodium (Na), which is lower than lithium on the periodic table and shares many of its properties.
Sodium is nearly 1,200 times more available worldwide than lithium, and its abundance makes it more affordable to mine and purify.
The deployment of Na-ion batteries, which operate by reversible insertion and extraction of Na into/from the electrode material, has been hampered by the lack of cathode materials capable of reversibly storing large amounts of charge.
“Viable sodium alternatives to current lithium batteries have proven elusive, in part because a limited number of sodium-ion electrode materials have been tested to date,” said Raphaële Clément, assistant professor in the Department of materials from UC Santa Barbara.
To find new sodium cathode materials, Clément proposes to study derivatives of Na2MgAlF7, a new class of high energy density compounds comprising elements abundant on Earth such as fluorine, sodium, magnesium, aluminum, manganese and iron.
The mineral weberite is a radical departure from systems that have already been explored for lithium, and previous research has shown that transition metal fluorides could be promising cathode materials for sodium.
To support his groundbreaking research, Clément received the Early CAREER Award, the most prestigious award given by the National Science Foundation (NSF) to support early career teachers. Under NSF’s CAREER program, Clement will receive more than $700,000 over five years to fund his proposed research and teaching activities.
“We are extremely proud of Raphaële Clément and congratulate her on receiving this prestigious award,” said Tresa Pollock, Acting Dean of UCSB’s College of Engineering (COE) and Alcoa Professor Emeritus of Materials. “She is a shining example of the high-quality junior faculty we have at the college, who seek to create new knowledge and innovations that address big challenges, such as energy efficiency and sustainability.”
“I welcome this opportunity to establish a long-term research agenda on topics I am passionate about, to engage with the general public and colleagues on issues related to climate change and climate justice, and to contribute to the material advances needed to develop the next generation of low-cost, long-lasting, high-energy-density rechargeable batteries,” said Clément, who joined UCSB in 2018 after earning his doctorate in chemistry from the University of Cambridge.
“I am grateful to have a fantastic group of undergraduate and graduate students and postdoctoral researchers. I would not have received this award without their hard work and enthusiastic approach to outreach and education,” she said.
As part of Clément’s project, High-Resolution NMR for Paramagnetic Sodium Electrodes, researchers in his lab will explore new materials at a fundamental level, seeking to understand the links between their chemistry, atomic structure and electrochemical performance.
They plan to achieve this, she explained, using nuclear magnetic resonance (NMR) spectroscopy, a powerful technique that can analyze the atomic structure of a material by tracking the interactions between nuclear spins and electronics (tiny magnetic bars associated with atomic nuclei and electrons) when the material is placed in a powerful magnetic field.
NMR allows scientists to study charge-discharge processes in battery materials.
“We plan to establish a new and unconventional NMR method to obtain atomic-level information about the operating principles of these battery electrodes,” said Clement, adding that his team wants to monitor minute changes in the crystal structure and electronic. “This understanding will then be used to design new materials and chemicals with improved properties.”
The first step will be to determine which electrode chemistries can be prepared in the laboratory using computer simulations. They will then prepare these compositions and use NMR and other techniques to study the role that crystal and electronic structures play in determining Na ion diffusion, electronic conductivity and phase stability.
Finally, they will develop a new theoretical method to predict the NMR properties of complex battery electrode materials.
Clément says the battery chemistries targeted in this project could have significant societal impacts because they completely eliminate the toxicity, raw material supply and cost issues that plague current Li-ion batteries.
“These materials hold promise for high-energy-density, high-power battery applications and could lead to the discovery of potentially transformative chemistries for large-scale energy storage,” she said.
Clement is the 10th junior faculty member at UCSB College of Engineering since April 2020 to receive a CAREER award. UCSB ranks first among public universities for the percentage of eligible junior faculty who received the awards from 2017-21.