Presently, the demand of lithium ion batteries (LIBs) in energy storage devices is increasing due to their performance in various applications from portable electronics to high energy electric vehicles. Thus, tremendous research has been focused on the mechanistic understanding of LIBs and their degradation mechanisms under high energy and power applications. Particularly of interest are investigations of high theoretical capacity electrode materials such as Si, Sn, Ge, S, O, metal oxides due to their ability to provide at least 2 to 5 times higher than present LIB energy of ~250 Wh/Kg. Amongst, significant research is focused on anode materials due to the prominence of reactions associated with LIB degradation, such as (i) anode/electrolyte reduction reactions and formation of solid products on the surface of anode, (ii) electrode volume expansion and phase changes while cycling, and (iii) lithium metal plating and dendrite formation. In order to visualize these nanoscale electrochemical mechanisms in real time, in-situ electrochemical S/TEM has been developed. Electrochemical S/TEM can be used to visualize the lithium insertion/de-insertion within anode materials, lithium plating and electrolyte-electrode reaction products with nanoscale resolution at or near working electrochemical conditions in real time. Herein, we present electrochemical S/TEM investigations of lithium insertion/de-insertion of nanosized Sn and Sn/TiO2 coated electrodes in commercially available organic electrolytes. Our custom designed platform contains 10 individually patterned electrodes with a liquid gap of ~ 150 nm which allows multiple customized electrochemical experiments inside the S/TEM with quantitative picoampere-level current control. The battery performance benefits of integrating a thin layer of TiO2 on the Sn electrodes will be demonstrated by presenting in-situ S/TEM to coin cell data.

In-situ electrochemical S/TEM of lithium-ion batteries with Sn and Sn@TiO2 anodes

256th National Meeting (2018)

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