Advancements in Thin Solid-State Electrolytes for High-Energy Lithium Metal Batteries
Authors: Yoo Seojeong , Choi Sung Ryul , Park Jun-Young 
Published: December 2024

ABSTRACT

In the next generation of lithium-ion batteries (LIBs) utilizing lithium metal as the anode material, a theoretical capacity of 3860 mAh·g-1 can be expected [1]. However, several challenges such as safety issues due to lithium dendrite diffusion during charge-discharge cycling still remain unresolved [2]. The penetration of lithium dendrites remains a concern in traditional solution-based LIBs [3]. As an alternative approach to address the challenges of LIBs, solid-state electrolytes (SSEs) with high ionic conductivity and lithium metal stability have garnered attention [4]. The SSE category includes polymer electrolytes, inorganic sulfide electrolytes, and inorganic oxide electrolytes [5]. Among SSEs, garnet-type Li7La3Zr2O7 (LLZO), is a promising candidate due to its high ionic conductivity within the range of 10-
4 to 10-
3 S∙cm-
1 as well as its thermodynamics reduction stability against Li metal [6, 7].

The introduction of SSB oxide electrolytes would improve packing density and could potentially lead to batteries with negligible self-discharge and longer lifespan of over 104 cycles [8]. During cell operation, solid electrolytes should be mechanically robust and as thin as possible to maximize the valuable volume remaining for the electrodes in SSB cell designs [9]. To compete with the approximately 20μm-thick polymer separators in traditional LIBs, ceramic manufacturing strategies for SSB electrolytes are necessary [10]. Recent estimations suggest that assuming a 25μm-thick solid electrolyte, a lithium metal SSB pouch cell could offer an energy density of 350Wh/kg [11]. In our study, we achieved ultra-thin electrolytes via tape-casting technique into Li-metal battery system. Li symmetric cells based on the ultra-thin electrolyte show exceptional low bulk resistance, attributed to extremely thin electrolyte. Moreover, symmetrical Li cell maintains steady Li plating/stripping cycles for long duration.

Keywords: Lithium-ion batteries, LLZTO, thick solid electrolyte

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