(Invited) Achieving High Areal Capacity and Extreme Critical Current Densities through Tailored Garnet Solid Electrolyte Structures

Abstract

Garnet structured electrolytes are an exceptional candidate to substitute for organic liquid electrolytes owing to its high ionic conductivity and safety.[1] One of the main issues preventing the commercialization of this electrolyte is limited lithium plating capacity and lithium dendrite shorting.[2] To address this, we invented new single-phase mixed ion electron conducting (MIEC) garnet with comparable lithium-ion and electron conductivity at room temperature. We demonstrate that in a trilayer architecture, with a porous MIEC framework supporting a thin dense garnet solid electrolyte, the critical current density can be as high as 100 mA/cm2, with no dendrite-induced shorting at room temperature and without any stack pressure. The single-phase MIEC conductor spreads the potential uniformly across the material surface preventing dendrite propagation through the dense garnet solid electrolyte layer. Additionally, high lithium stripping capacity and impressive cycling stability were observed at commercial level current densities of well over 10 mA/cm2. The role of the porous MIEC garnet structure is elucidated using various electrochemical and electron microscopy techniques. Wang, C. et al. Garnet-Type Solid-State Electrolytes: Materials, Interfaces, and Batteries. Chem. Rev. 120, 4257–4300 (2020).Albertus, P., Babinec, S., Litzelman, S. & Newman, A. Status and challenges in enabling the lithium metal electrode for high-energy and low-cost rechargeable batteries. Nat. Energy 2017 31 3, 16–21 (2017).