A New Way to Find Better Battery Materials
March 26, 2018 | MITEstimated reading time: 3 minutes
A new approach to analyzing and designing new ion conductors—a key component of rechargeable batteries—could accelerate the development of high-energy lithium batteries, and possibly other energy storage and delivery devices such as fuel cells, researchers say.
The new approach relies on understanding the way vibrations move through the crystal lattice of lithium ion conductors and correlating that with the way they inhibit ion migration. This provides a way to discover new materials with enhanced ion mobility, allowing rapid charging and discharging. At the same time, the method can be used to reduce the material’s reactivity with the battery’s electrodes, which can shorten its useful life. These two characteristics—better ion mobility and low reactivity—have tended to be mutually exclusive.
The new concept was developed by a team led by W.M. Keck Professor of Energy Yang Shao-Horn, graduate student Sokseiha Muy, recent graduate John Bachman PhD ’17, and Research Scientist Livia Giordano, along with nine others at MIT, Oak Ridge National Laboratory, and institutions in Tokyo and Munich. Their findings were reported in the journal Energy and Environmental Science.
The new design principle has been about five years in the making, Shao-Horn says. The initial thinking started with the approach she and her group have used to understand and control catalysts for water splitting, and applying it to ion conduction — the process that lies at the heart of not only rechargeable batteries, but also other key technologies such as fuel cells and desalination systems. While electrons, with their negative charge, flow from one pole of the battery to the other (thus providing power for devices), positive ions flow the other way, through an electrolyte, or ion conductor, sandwiched between those poles, to complete the flow.
Typically, that electrolyte is a liquid. A lithium salt dissolved in an organic liquid is a common electrolyte in today’s lithium-ion batteries. But that substance is flammable and has sometimes caused these batteries to catch fire. The search has been on for a solid material to replace it, which would eliminate that issue.
A variety of promising solid ion conductors exist, but none is stable when in contact with both the positive and negative electrodes in lithium-ion batteries, Shao-Horn says. Therefore, seeking new solid ion conductors that have both high ion conductivity and stability is critical. But sorting through the many different structural families and compositions to find the most promising ones is a classic needle in a haystack problem. That’s where the new design principle comes in.
The idea is to find materials that have ion conductivity comparable to that of liquids, but with the long-term stability of solids. The team asked, “What is the fundamental principle? What are the design principles on a general structural level that govern the desired properties?” Shao-Horn says. A combination of theoretical analysis and experimental measurements has now yielded some answers, the researchers say.
“We realized that there are a lot of materials that could be discovered, but no understanding or common principle that allows us to rationalize the discovery process,” says Muy, the paper’s lead author. “We came up with an idea that could encapsulate our understanding and predict which materials would be among the best.”
The key was to look at the lattice properties of these solid materials’ crystalline structures. This governs how vibrations such as waves of heat and sound, known as phonons, pass through materials. This new way of looking at the structures turned out to allow accurate predictions of the materials’ actual properties. “Once you know [the vibrational frequency of a given material], you can use it to predict new chemistry or to explain experimental results,” Shao-Horn says.
The researchers observed a good correlation between the lattice properties determined using the model and the lithium ion conductor material’s conductivity. “We did some experiments to support this idea experimentally” and found the results matched well, she says.
They found, in particular, that the vibrational frequency of lithium itself can be fine-tuned by tweaking its lattice structure, using chemical substitution or dopants to subtly change the structural arrangement of atoms.
The new concept can now provide a powerful tool for developing new, better-performing materials that could lead to dramatic improvements in the amount of power that could be stored in a battery of a given size or weight, as well as improved safety, the researchers say. Already, they used the method to find some promising candidates. And the techniques could also be adapted to analyze materials for other electrochemical processes such as solid-oxide fuel cells, membrane based desalination systems, or oxygen-generating reactions.
Suggested Items
Groundbreaking Ceremony Marks the Beginning of a New Era for Newccess Industrial; The Construction of the MINGXIN Building
04/12/2024 | Newccess IndustrialOn a clear and sunny day in March, the groundbreaking ceremony for the MINGXIN Building took place in Shenzhen, China. This moment marked the official commencement of construction for a project that will reshape the semiconductor materials industry.
The Need for a Holistic Global Sustainability Standard
04/10/2024 | Michael Ford, Aegis SoftwareNo one can deny that the resources of our fragile planet are finite. The environment seems like a third party, subject to constant degradation. We’re acutely aware of the effects of pollution on our climate, and despite our “throw-away” culture, recycling and recovery of materials has remained relatively expensive, even as we use more energy just to survive.
iNEMI Publishes Four Roadmap Topics
04/04/2024 | iNEMIThe International Electronics Manufacturing Initiative (iNEMI) announces the availability of the first roadmap topics in the new iNEMI Roadmap format. Printed circuit boards, sustainable electronics, smart manufacturing, and mmWave materials and test are now available online.
Insulectro’s 'Storekeepers' Extend Their Welcome to Technology Village at IPC APEX EXPO
04/03/2024 | InsulectroInsulectro, the largest distributor of materials for use in the manufacture of PCBs and printed electronics, welcomes attendees to its TECHNOLOGY VILLAGE during this year’s IPC APEX EXPO at the Anaheim Convention Center, April 9-11, 2024.
Checking In With ICAPE Group
04/03/2024 | Nolan Johnson, I-Connect007ICAPE Group’s field application engineer Erik Pederson drills down on sustainability, supply chain resiliency, and what value engineering really looks like in this exclusive interview. Founded in 1999, European-based ICAPE Group provides 21 million printed circuit boards and over six million technical parts to manufacturers every month. With 30 PCB manufacturing partners globally and 50 partners providing a wide array of technical parts, ICAPE Group has operations in China, Taiwan, Thailand, South Korea, Vietnam, South Africa, Europe, Mexico, and the United States. The company also focuses on the value proposition for its customers.