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 Ω cm2 as compared to 1652 Ω cm2 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 °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.
Solid-state batteries (SSBs) are promising for next-generation energy storage with advantages in both energy density and safety, but are challenged by the poor solid-to-solid contact between solid-state electrolytes (SSEs) and electrodes, particularly the lithium anode. Herein, a facile coordination-assisted deposition process is employed to build artificial Ta 2 O 5 nanofilms on SSEs, which is lithiophilic and has high stability against metallic lithium, thereby ensuring an intimate and stable interface between SSEs and lithium anode to sustain extended cycles. The feasibility is verified by using Li 6.5 La 3 Zr 1.5 Ta 0.5 O 12 (LLZT), a garnet-typed SSEs, as a model system. It is shown that a 12 nm Ta 2 O 5 nanofilm is able to significantly decrease the interfacial resistance from 1258 to 9 Ω cm 2 with a high critical current density reaching 2.0 mA cm −2 for the assembled symmetric cell, which shows an unprecedented capability to survive long-term cycling over 5200 h. This control strategy is also able to enable the use of the commercialized cathode materials of LiFePO 4 and LiNi 0.83 Co 0.07 Mn 0.1 O 2 in SSBs with both high reversible capacity and cycling capability. The study opens up a research avenue for the delicately carved interlayers through a scalable and reliable manufacturing process which can accelerate the commercialization of SSEs.
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