Toward all-solid-state lithium metal batteries
San Diego, Calif., September 17, 2020 -- Battery researchers know that solid-state electrolytes, such as lithium phosphorus oxynitride (LiPON), remain electrochemically stable against Lithium (Li) metal. But they don't know why exactly.
Figuring out why and how specific solid-state electrolytes like LiPON remain stable and cycleable when in contact with lithium metal anodes is an important step toward finally incorporating lithium metal anodes into next generation all-solid-state lithium metal batteries.
Lithium metal batteries, which have anodes made of lithium metal, are an essential part of the next generation of battery technologies. They promise twice the energy density of today’s lithium-ion batteries (which usually have anodes made of graphite), so they could last longer and weigh less. This could potentially double the range of electric vehicles.
New work published in September 2020 in the journal Joule, led by researchers in the lab of UC San Diego nanoengineering professor Shirley Meng, will help explain this stability. In particular, the work unravels some of the mystery of the interface between lithium metal and LiPON.
"This research provides new insights for interface engineering aimed at stabilizing the lithium metal anode," said Diyi Cheng, a nanoengineering PhD student in Shirley Meng's lab at the UC San Diego Jacobs School of Engineering.
The team uncovered an 80-nm-thick interface comprising nanocrystals embedded in an amorphous matrix. Analyzing its chemical distribution is leading to a mechanistic understanding of solid-solid interface formation in lithium metal batteries.
This work combines cryogenic electron microscopy and cryogenic focused ion beam (FIB). The methodology in this work can be then extended to the interface studies in other battery systems using either organic liquid or solid-state electrolytes.
Paper title: Unveiling the Stable Nature of the Solid Electrolyte Interphase between Lithium Metal and LiPON via Cryogenic Electron Microscopy
Authors: Diyi Cheng, Thomas A. Wynn, Xuefeng Wang, Shen Wang, Minghao Zhang, Ryosuke Shimizu, Shuang Bai, Han Nguyen, Chengcheng Fang, Min-cheol Kim, Weikang Li, Bingyu Lu, Suk Jun Kim, and Ying Shirley Meng.
Materials Science and Engineering Program, University of California San Diego, La Jolla, CA 92121, USA
Department of NanoEngineering, University of California San Diego, La Jolla, CA 92121, USA
School of Energy, Materials and Chemical Engineering, Korea University of Technology and Education, Cheonan 31253, Republic of Korea
Jacobs School of Engineering