Wednesday, September 5, 2018

Waterloo chemists make battery breakthrough

An electric vehicle is plugged in to a charging station near Engineering 6. Photograph by Nina Yan.

Chemists from the University of Waterloo have successfully resolved two of the most challenging issues surrounding lithium-oxygen batteries, and in the process created a working battery with near 100 per cent coulombic efficiency.

The new work, which appeared last week in Science, proves that four-electron conversion for lithium-oxygen electrochemistry is highly reversible. The team is the first to achieve four-electron conversion, which doubles the electron storage of lithium-oxygen, also known as lithium-air, batteries.

“There are limitations based on thermodynamics,” said Linda Nazar, the Canada Research Chair in Solid State Energy Materials and senior author on the project. “Nevertheless, our work has addressed fundamental issues that people have been trying to resolve for a long time.”

The high theoretical-energy density of lithium-oxygen (Li-O₂) batteries and their relatively light weight have made them the Holy Grail of rechargeable battery systems. But long-standing issues with the battery’s chemistry and stability have kept them a purely academic curiosity.

Two of the more serious issues involve the intermediate of the cell chemistry (superoxide, LiO₂) and the peroxide product (Li₂O₂) reacting with the porous carbon cathode, degrading the cell from within. In addition, the superoxide consumes the organic electrolyte in the process, which greatly limits the cycle life.

Nazar and her colleagues switched the organic electrolyte to a more stable inorganic molten salt and the porous carbon cathode to a bifunctional metal oxide catalyst. Then by operating the battery at 150 C, they found that the more stable product Li₂O is formed instead of Li₂O₂. This results in a highly reversible Li-oxygen battery with coulombic efficiency approaching 100 per cent.

By storing O₂ as lithium oxide (Li₂O) instead of lithium peroxide (Li₂O₂), the battery not only maintained excellent charging characteristics, it achieved the maximum four-electron transfer in the system, thereby increasing the theoretical energy storage by 50 per cent.

“By swapping out the electrolyte and the electrode host and raising the temperature, we show the system performs remarkably well,” said Nazar, who is also a University Research Professor in the Department of Chemistry and a member of the Waterloo Institute for Nanotechnology.

The lead author on the study is Chun Xia, a postdoctoral fellow, and co-author is Chun Yuen Kwok, a PhD student, both in Nazar’s lab.

The Natural Sciences and Engineering Research Council of Canada in part funded the project through their Discovery Grants and Canada Research Chair programs, along with the U.S. Department of Energy’s Joint Center for Energy Storage Research.

Mel Edwards hired as Equity Coordinator

"I am pleased to announce that Mel Edwards has joined the University of Waterloo as our Equity Coordinator," writes Director of Equity Gina Hickman. "In this role, Mel will work closely with me to implement key equity initiatives across campus. Among her other responsibilities, Mel will do research to inform evidence-based planning, support the working groups of PACE, and engage with student groups on campus."

Edwards recently completed her Master of Social Work at Wilfrid Laurier University, where she focused on building an anti-oppressive skillset within organizational settings. During her Master’s degree, she was part of the Laurier Graduate Students’ Association, where she focused on providing student support and creating inclusive spaces. While at Laurier, she also evaluated the Faculty of Social Work Equity Strategic Plan and proposed actions and future directions.

Edwards has also worked at the Region of Waterloo and the Waterloo Wellington Local Health Integration Network. In all her positions, she focused on working towards equity and inclusion by making space for the voices of marginalized individuals. She is also strongly committed to working from an informed, evidence-based perspective and welcomes the opportunity to expand these skills. She looks forward to her work at with the Human Rights, Equity and Inclusion Office and to collaborating with students, staff and faculty across campus.

Mel lives in Waterloo with her partner (who attends Waterloo), and a very loud, cranky cat. Mel can be reached at x40025 or you can drop by her office in MC-1033.

Welcoming new retirees and other notes

Human Resources is reporting that the following employees retired as of September 1, 2018:

• Kitty King Corbett, who joined the University in September 2014, retired as Definite Term Faculty in the School of Public Health and Health Systems;
• Margaret (Peggy) Day, who started working at Waterloo in February 1977, retired as Manager, Client Services in IST;
• Christopher Pringle, who began working at the University in February 2007, retired as Director, Industry and Government Relations in Mechanical and Mechatronics Engineering;
• Catherine Fraser, who started at Waterloo in January 1985, retired as Records Assistant/Alumni and Donor Services Assistant – Advancement;
• Ralph Smith, who began working at the University in September 1987, retired as Professor in Biology;
• Ingrid Stewart, who started working at Waterloo in October 1998, retired as General Cafeteria Helper – Food Services;
• John Jaworsky, who joined the University in July 1987, retired as Assistant Professor in Political Science;
• Donald McKay; who started at Waterloo in May 1979, retired as Associate Professor in Architecture;
• Ellsworth LeDrew, who began working at the University in July 1977, retired as University Professor in Geography & Environmental Management;
• John Quaiser, who started at Waterloo in November 1988, retired as  Building Service person II – Carpenter – Plant Operations – Buildings;
• Elaine Lillie, who began working at the University in October 2007, retired as Director, Interprofessional Education Program and Curriculum Development – School of Pharmacy;

• Susan Andrews, who started in December 1981, retired as Academic Advisor in the Arts Undergraduate Office;

• J. Randall Zlak, who began working at the University in March 2003, retired as Custodian 1 – Plant Operations;

• Gerald Underhill, who joined Waterloo in December 1988, retired as Library Clerk Payroll – Library;

• Jennifer Williams, who started at the University in June 1976, retired as Library Clerk – Receiving, Holdings maintenance – Library;

• Gregory Stoeser, who began working at Waterloo in September 1977, retired as Building Service person II – Plant Operations;

• Remedios (Mitzi) Schnabel, who joined the University in February 2011, retired as Administrative Coordinator in the David R. Cheriton School of Computer Science;

• James (Jim) Tremain, who started at Waterloo in August 1980, retired as Biology Lab Technician – Zoology in Biology;

• Harry Merkel, who began working at the University in January 1991, retired as Stationary Engineer 3^rd Class – Plant Operations – Central Plant;

• Glenn Welch, who started at Waterloo in July 1985, retired as Supervisor, Custodial – Plant Operations;

• Denise Wilson, who began working at the University in September 1995, retired as Food Services Assistant – Food Services; and

• Maria Guterres, who joined Waterloo in April 2001, retired as Custodian 11 – Plant Operations – custodial.

Congratulations all!

The Bombshelter Pub is back open and is excited to have you over for lunch. "With new items on the menu that are sure to satisfy any cravings, The Bombshelter Pub is looking forward to cooking up another great term!" says a note from the Federation of Students. "See you at the Bomber!"

On Friday, September 7 at noon, please join the Department of Music for an impromptu music concert in the beautiful Peter Russell Rock Garden. Music by the Rocks will start at noon and go for approximately an hour, weather permitting. Members of the Balinese Gamelan Ensemble will perform and you may even get a chance to try out an instrument yourself. Bring your lunch and stay a while.

Employers on campus next week hosting employer information sessions include EY, Bell, Canadian Tire, Vue Real Inc, Novantas Inc, Procter & Gamble, Wish, RBC, Manulife, Munich RE, Google, Thomas Reuters, BDO, FDM, Suncor, Kiewit, LinkedIn, Facebook, Eckler, Clearpath, Imperial, Connected Lab, Intact, Public Accounting Night, Scotiabank, Pixlee, and Toast. Visit the Employer Information Calendar for more details.