title: Dendrites and Pits: Untangling the Complex Behavior of Lithium Metal Anodes through Operando Video Microscopy.
abstract: Enabling ultra-high energy density rechargeable Li batteries would have widespread impact on society. However the critical challenges of Li metal anodes (most notably cycle life and safety) remain unsolved. This is attributed to the evolution of Li metal morphology during cycling, which leads to dendrite growth and surface pitting. Herein, we present a comprehensive understanding of the voltage variations observed during Li metal cycling, which is directly correlated to morphology evolution through the use of operando video microscopy. A custom-designed visualization cell was developed to enable operando synchronized observation of Li metal electrode morphology and electrochemical behavior during cycling. A mechanistic understanding of the complex behavior of these electrodes is gained through correlation with continuum-scale modeling, which provides insight into the dominant surface kinetics. This work provides a detailed explanation of (1) when dendrite nucleation occurs, (2) how those dendrites evolve as a function of time, (3) when surface pitting occurs during Li electrodissolution, (4) kinetic parameters that dictate overpotential as the electrode morphology evolves, and (5) how this understanding can be applied to evaluate electrode performance in a variety of electrolytes. The results provide detailed insight into the interplay between morphology and the dominant electrochemical processes occurring on the Li electrode surface through an improved understanding of changes in cell voltage, which represents a powerful new platform for analysis.
authors.affiliation: Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States; Joint Center for Energy Storage Research, University of Michigan, Ann Arbor, Michigan 48109, United States.
authors.forename: Kevin N
authors.initials: KN
authors.lastname: Wood
authors.affiliation: Department of Mechanical Engineering, University of Michigan , Ann Arbor, Michigan 48109, United States.
authors.forename: Eric
authors.initials: E
authors.lastname: Kazyak
authors.affiliation: Joint Center for Energy Storage Research, University of Michigan, Ann Arbor, Michigan 48109, United States; Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States.
authors.forename: Alexander F
authors.initials: AF
authors.lastname: Chadwick
authors.affiliation: Department of Mechanical Engineering, University of Michigan , Ann Arbor, Michigan 48109, United States.
authors.forename: Kuan-Hung
authors.initials: KH
authors.lastname: Chen
authors.affiliation: Joint Center for Energy Storage Research, University of Michigan, Ann Arbor, Michigan 48109, United States; Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, United States.
authors.forename: Ji-Guang
authors.initials: JG
authors.lastname: Zhang
authors.affiliation: Joint Center for Energy Storage Research, University of Michigan, Ann Arbor, Michigan 48109, United States; Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States.
authors.forename: Katsuyo
authors.initials: K
authors.lastname: Thornton
authors.affiliation: Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States; Joint Center for Energy Storage Research, University of Michigan, Ann Arbor, Michigan 48109, United States.
authors.forename: Neil P
authors.initials: NP
authors.lastname: Dasgupta