Charging a lithium-ion battery at -100°C to set Guinness World Record
Lithium-ion batteries (LIBs) are everywhere in our lives. LIB application fields are even growing into military missions and advanced exploration, which require resistance to severe cold in the polar region of the Earth and in outer space. But even state-of-the-art LIBs suffer from huge performance degradation as temperatures decrease, and they stop operating at all in extreme cold.
We need to design and engineer novel electrolytes with tailored chemical, electrochemical and physical properties to address the challenge. Our Vilas Pol Energy Research (ViPER) group introduced a low-melting-point ether solvent to do just that: maintain the liquid state within a lithium-ion battery in extreme cold.
Guinness World Records™ took note. During a demonstration in a specially designed ultralow temperature lab, we charged and discharged multiple lithium-ion batteries at -100°C. Accordingly, we hold the Guinness World Records title for the “lowest temperature to charge a lithium-ion battery.”
The award certificate is more than a novelty. This discovery goes a long way toward overcoming the absence of reliable power storage in extreme conditions. This limitation poses a major roadblock to strengthening national security, by hindering our increased presence in those environments. For example, for successful space exploration of Mars and the moon, the first important thing we need to have is the energy conversion (solar) and storage (batteries) sources working together to provide the requisite energy supply to the mission.
The traditional approach to battery uses in extreme cold conditions is a secondary heating system installation to maintain the battery’s proper internal temperatures. This method cannot resolve the intrinsic limitation of the LIB; the power sources to operate the heating system also must come from somewhere. Therefore, we must incur additional cost, energy and mass to generate heat for thermal insulation. Our idea was to remove those hurdles and make the lithium-ion batteries function without add-on heating or cooling systems.
Electrolyte-related issues, such as electrolyte freezing and inefficient lithium-ion (Li+) transport, have been identified as a primary factor for the poor performance of LIBs at cold temperatures. The currently used high-melting-point carbonate-based solvents freeze around -10°C and show high Li+ desolvation energy, dramatically decreasing ionic conductivity at cold temperatures.
Our low-melting-point ether solvent (cyclopentyl methyl ether, or CPME) overcomes that constraint. Although ether solvents have been avoided for LIB electrolytes because of limited stability, we adjusted Li+ solvation in the CPME-based electrolyte to use it for an LIB electrolyte.
Apart from the electrolyte side, simulating the extreme cold temperature conditions for the battery tests was confined by commercially available battery cyclers and temperature chambers. Therefore, we also devised a battery testing system to efficiently measure performance of our batteries at extreme cold temperatures (from room temperature to 185°C).
While electrolyte research has enhanced LIB performance in cold climate conditions, the fundamental underpinning principles for Li+ transport in the electrolytes remain unknown, presenting a colossal knowledge gap. Because we cannot directly observe how Li+ moves in the batteries due to the operational nature of the LIBs, mathematical, computational and experimental techniques are necessary to design and optimize LIBs for extreme cold temperature usage.
Our research was supported by the Office of Naval Research (ONR), with assistance from the Purdue Research Foundation in filing patents and the Purdue Office of Technology Commercialization in identifying licensing opportunities. Our team collaborates closely with Thomas Adams, PhD, a research engineer at the Naval Surface Warfare Center Crane (NSWC Crane), to materialize the successful creation, demonstration and utilization of advanced LIB batteries in submarines, high-altitude air vehicles, and the polar regions of Earth.
LIBs functioning at lower temperatures have a great future in the U.S. Space Force and other military and space applications. Achieving a Guinness World Record is a first step toward demonstrating that developing such complex battery technologies is possible. This evidence provides enthusiasm, encouragement and passion for young researchers to think of novel solutions and go beyond the current state of the art.
A Purdue graduate student researcher, Soohwan Kim, played a significant role in achieving the Guinness World Record. He designed an instrument able to reach the extreme low temperature, as well as developed the electrolyte that makes the battery operational without freezing the electrolyte at that ultralow temperature — leading to numerous tangential inventions and published papers.
Advanced lithium-ion batteries, emanating from a Purdue discovery, could be the next “giant leap.”
After all, Purdue Engineering graduate Neil Armstrong was the first person to step on the moon, on July 20, 1969.
Vilas G. Pol
Professor, Davidson School of Chemical Engineering
Head, Vilas Pol Energy Research (ViPER) Group
College of Engineering
Purdue University
