May is Asian American and Native Hawaiian/Pacific Islander Heritage Month, also known as Asian American Pacific Islander Heritage Month and Women of Color Online is celebrating the achievements of diverse winners at the Women of Color (WOC) STEM Conference.

When Mei Cai, Ph.D., won the Technologist of the Year Award at the 2021 WOC STEM Conference, she joined an illustrious group of women in science, technology, engineering, and math (STEM) fields. GM nominated Mei to receive an award because of the cutting-edge innovations she has led in research and development.

Currently, she is director of battery cell systems research in the Chemical & Materials System Laboratory of General Motors Research and Development.

According to Mark Verbrugge, director of the Chemical & Materials Systems Laboratory at GM Research and Development, Mei is among the few scientists contributing to advancing battery materials discovery and accelerating battery cell manufacturing.

Mei’s contributions to advanced energy storage materials include lithium-ion and advanced battery chemistries, proton-exchange membrane fuel cells, hydrogen, compressed natural gas storage, and battery charging and hydrogen production technologies.

Mei has played a pivotal role in developing GM’s Ultium battery chemistry, which will power vehicles like the GMC Hummer EV and the Cadillac Lyriq.

GM’s Ultium batteries are unique because the pouch-style cells can be stacked vertically or horizontally inside the battery pack. This allows engineers to optimize battery energy storage and layout for each vehicle design.

Mei and her team also drove vital technologies to enable lithium-metal batteries that could be part of the basis for next-generation Ultium cells.

According to Verbrugge, GM can use these batteries to increase the onboard energy of its electric vehicles, enabling greater range or more energy-dense batteries in lower-cost products.

The design enabled a structurally integrated RESS capable of sustaining vehicle use and abuse conditions. The compact cooling system improves the energy efficiency of the battery pack but also simplifies the manufacturing process. Other technologies that Mei and her team have patented include:

The three-electrode setup allows for independent diagnostics of the positive or negative electrode and, hence, precise detection of lithium plating and calibration for on-vehicle charging control. This innovative design paves the road toward accelerated advanced high-energy and high-power EV batteries with reduced cost.

Mei is a member of the Materials Research Society, Detroit Engineer Association, Electrochemical Society, and the International Academy of Electrochemical Energy Science.

“I came to this country close to 30 years ago as a spouse,” she said. “I had to learn English here and prepare for graduate school testing.”