Innovative solid-state battery fabrication and interface engineering for sustainable transportation and green energy systems

Lithium-ion solid-state batteries (SSBs) play a key role in the next-generation battery technology. This work compares the characteristics and fabrication procedures of sulfide-based and oxide-based solid electrolytes (SEs). Since ionic conductivity is a critical factor in battery performance, we investigated the ionic conductivity of both SE types under external pressures ranging from 0 to 250 MPa. To evaluate interfacial stability with electrodes, symmetrical cell experiments were conducted. In an all-solid-state sulfide full cell using Li 7 P 3 S 11 (LPS) as the SE, cold pellet pressing was employed, demonstrating excellent cycling stability at rates of 0.1C - 1.0C. For the hybrid solid-state oxide full cell using Li 6 . 4 La 3 Zr 1 . 4 Ta 0 . 6 O 12 (LLZTO) as the SE, advanced fabrication techniques such as rapid heat radiation sintering, cathode wetting, and Li-Sn alloy anode soldering were utilized. This approach enabled a lifespan exceeding 200 cycles with ∼78% capacity retention at the 200th cycle compared to the peak capacity. This work compares the fabrication procedure differences between the cathode wetting procedure for the hybrid oxide solid-state battery and the dry cathode procedure for the all-solid-state sulfide battery, where the hybrid cell displays ∼72% more capacity and more than 100-cycle of lifespan compared to the all-solid-state cell. Additionally, it is common for researchers to mix solid electrolytes in the solid-state cathode material to increase the ionic conductivity, but this limits the energy density and increases complexity for future mass production purposes [11,12,47]. This paper employed a novel cathode fabrication technique that employed commercial cathode with 93 wt% active material in the hybrid cell to maximize the energy density and the feasibility of mass production. Interfacial resistance analysis was performed by fitting equivalent circuits to the full cell impedance curves. The interfacial resistance was further decoupled into contributions from the cathode and anode. This study provides insights into various SSB fabrication procedures, ionic conductivity, and interfacial behavior, offering a comparative analysis to support the development of next-generation solid-state batteries. • Sulfide-based all-solid-state lithium-ion batteries were fabricated using cold pellet pressing technique and investigated. • Battery performance was investigated on hybrid-solid-state battery with oxide-based solid electrolyte fabricated with rapid heat radiation sintering, cathode wetting, and alloy anode soldering techniques. • Ionic conductivity, interfacial resistance and cycling performance were investigated on hybrid- and all-solid-state full cells using optimized equivalent circuits.