Facile Construction of Nanofilms from a Dip-Coating Process to Enable High-Performance Solid-State Batteries

The use of solid-state electrolytes (SSEs) instead of those liquid ones has found promising potential to achieve both high energy density and high safety for their applications in the next-generation energy storage devices. Unfortunately, SSEs also bring forth challenges related to solid-to-solid contact, making the stability of the electrode/electrolyte interface a formidable concern. Herein, using a garnet-type Li6.5La3Zr1.5Ta0.5O12 (LLZT) electrolyte as an example, we demonstrated a facile treatment based on the dip-coating technique, which is highly efficient in modifying the LLZT/Li interface by forming a MgO interlayer. Using polyvinyl pyrrolidone (PVP) as a coordination polymer, uniform and crack-free nanofilms are fabricated on the LLZT pellet with good control of the morphological parameters. We found that the MgO interlayer was highly effective to reduce the interfacial resistance to 6 omega cm(2) as compared to 1652 omega cm(2) of the unmodified interface. The assembled Li symmetrical cell was able to achieve a high critical current density of 1.2 mA cm(-2) at room temperature, and it has a long cycling capability for over 4000 h. Using the commercialized materials of LiFePO4 and LiNi0.83Co0.07Mn0.1O2 as the cathode materials, the full cells based on the LLZT@MgO electrolyte showed excellent cyclability and high rate performance at 25 degrees C. Our study shows the feasibility of precise and controllable surface modification based on a simple liquid phase method and highlights the essential importance of interface control for the future application of high-performance solid-state batteries.

Automated summary

The use of solid-state electrolytes (SSEs) instead of liquid ones shows potential for high energy density and safety in next-generation energy storage devices. However, solid-to-solid contact poses challenges to the stability of the electrode/electrolyte interface. In this study, a facile treatment using the dip-coating technique was demonstrated to modify the LLZT/Li interface by forming a MgO interlayer. The modified interface showed significantly reduced interfacial resistance and the assembled Li symmetrical cell exhibited high critical current density and long cycling capability. Full cells based on the LLZT@MgO electrolyte showed excellent cyclability and high rate performance.