Interphases Formation and Analysis at the Lithium–Aluminum–Titanium–Phosphate (LATP) and Lithium–Manganese Oxide Spinel (LMO) Interface during High‐Temperature Bonding

Abstract

In this study, fabrication processes of solid electrolyte/cathode interfaces for their use in next‐generation all‐solid‐state lithium‐ion battery (LIB) applications are described. Standard lithium–aluminum–titanium–phosphate (LATP) solid electrolyte and lithium–manganese oxide (LMO) spinel cathode ceramic half cells are assembled using two all‐solid‐state methods: a) co‐sintering the cathode and electrolyte materials via field‐assisted sintering and b) field‐assisted high‐temperature bonding. The morphology and composition of the interfaces are analyzed by scanning electron microscopy (SEM) and energy‐dispersive X‐ray spectroscopy (EDS). This study reveals that the formation of interphases can be significantly decreased by separately performing the densification and joining procedures. Electrochemical impedance spectroscopy (EIS) is applied to understand and determine the effect of the manufactured interfaces on the system conductivity. Based on the results, it is concluded that the high‐temperature bonding technique appears to be a suitable technique for future production of all‐solid‐state LIBs.

Origin of High Interfacial Resistance in Solid‐State Batteries: LLTO/LCO Half‐Cells**

“…LLTO/LCO half‐cells joined via SPS were prepared through a two‐step joining process [47,48] as sketched in Figure 1(a). In the first step, LLTO and LCO powders were first sintered individually by a Thermal Technology SPS 10–3 machine into 1 mm thick pellets.…”

“…The pellets were sintered at 850 °C and 50 MPa for 10 minutes, with a heating/cooling rate of 100 °C/min. To relief the thermal stress at the interface and avoid the formation of cracks, a separate joining process was designed at a lower temperature of 700 °C [48] . LLTO and LCO pellets were polished with SiC paper (800 Grit) and then joined by SPS at 700 °C and 20 MPa for 10 minutes.…”

“…The thoroughly mixed powders were sintered by SPS at 850°C and 50 MPa for 10 minutes, with a heating and cooling rate of 100°C/min. LLTO/LCO half-cells joined via SPS were prepared through a two-step joining process [47,48] as sketched in Figure 1(a). In the first step, LLTO and LCO powders were first sintered individually by a Thermal Technology SPS 10-3 machine into 1 mm thick pellets.…”

“…To relief the thermal stress at the interface and avoid the formation of cracks, a separate joining process was designed at a lower temperature of 700°C. [48] LLTO and LCO pellets were polished with SiC paper (800 Grit) and then joined by SPS at 700°C and 20 MPa for 10 minutes. The heating rate was 100°C/min and the cooling rate was 10°C/min.…”

Compatibility assessment of solid ceramic electrolytes and active materials based on thermal dilatation for the development of solid-state batteries

“…Preparing such batteries requires mixing solid electrolytes with active materials and conductive fillers in the electrode part to ensure optimized interfaces between active material and electrolytes. This is often achieved with oxidebased materials via high temperature processing between 600 and 1200°C [10][11][12][13][14][15] . In the electrolyte part itself, sintering at high temperature allows the ceramic grains to merge, this leads to a reduction of overall porosity.…”