Another Way to Realize LiMn₂O₄ as a Solid Electrolyte

The development and application of solid-state electrolytes (SSEs) play a crucial role in advancing lithium metal batteries (LMBs). Consequently, the search for high-performance, economic, and easily fabricated SSEs has become a prevailing trend. In this work, we explore an alternative approach to design the traditional commercial lithium-ion batteries cathode material, spinel-type LiMn₂O₄ (LMO) as a SSE. By blending LMO with poly(vinylidene difluoride) and combining with two layers of polyethylene (PE) film on the top and bottom, we effectively reduce its high electronic conductivity, thereby creating the PE/LMO/PE SSE. The PE/LMO/PE SSE demonstrates high ionic conductivity (3.15 × 10⁻⁴ S cm⁻¹ at 35°C), low electronic conductivity (7.31 × 10⁻¹¹ S cm⁻¹), and good interfacial contact and stability with both the lithium metal anode, LiFePO₄ and nickel-rich Li[Ni_0.8Co_0.1Mn_0.1]O₂ cathodes. This study offers a new direction for the application of the electrochemically active cathode material LMO, while providing a simple and feasible solution to reduce the electronic conductivity of SSEs. Additionally, it opens up new perspectives for selecting high-performance SSEs for use in LMBs, paving an alternative economic path toward the commercialization of solid-state lithium metal batteries.