We have realized the more realistic environment for observing battery reactions in a high-vacuum TEM by encapsulating active materials and a commercialized electrolyte solution with graphene layers. As the first work, the initial lithiation dynamics in silicon was successfully disclosed and published. (ACS Nano 8, 7478-7485 (2016)) The technique has been further developed and utilized to observe the non-continuous growth process of solid-electrolyte interphase. (Nano Energy 25, 154-160 (2016)). Recently, sodium storage mechanism in copper sulfide has been unveiled utilizing a similar technique (Nat. Commun. 9, 922 (2018), selected Editors' Highlights)
With collaborations of ex-situ cell measurements, we are recently widening our research interests on revealing the critical issues on various battery systems (sodium-ion, magnesium-ion, Li-sulfur, Li-air, etc.) to provide fundamental bases for rational designs of the next generation batteries.