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Abstract A thin solid electrolyte with a high Li+conductivity is used to separate the metallic lithium anode and the cathode in an all‐solid‐state Li‐metal battery. However, most solid Li‐ion electrolytes have a small electrochemical stability window, large interfacial resistance, and cannot block lithium‐dendrite growth when lithium is plated on charging of the cell. Mg2+stabilizes a rhombohedral NASICON‐structured solid electrolyte of the formula Li1.2Mg0.1Zr1.9(PO4)3(LMZP). This solid electrolyte has Li‐ion conductivity two orders of magnitude higher at 25 °C than that of the triclinic LiZr2(PO4)3.7Li and6Li NMR confirm the Li‐ions in two different crystallographic sites of the NASICON framework with 85% of the Li‐ions having a relatively higher mobility than the other 15%. The anode–electrolyte interface is further investigated with symmetric Li/LMZP/Li cell testing, while the cathode–electrolyte interface is explored with an all‐solid‐state Li/LMZP/LiFePO4cell. The enhanced performance of these cells enabled by the Li1.2Mg0.1Zr1.9(PO4)3solid electrolyte is stable upon repeated charge/discharge cycling.
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Origin of High Interfacial Resistance in Solid‐State Batteries: LLTO/LCO Half‐Cells**
Abstract The interface between cathode and electrolyte is a significant source of large interfacial resistance in solid‐state batteries (SSBs). Spark plasma sintering (SPS) allows densifying electrolyte and electrodes in one step, which can improve the interfacial contact in SSBs and significantly shorten the processing time. In this work, we proposed a two‐step joining process to prepare cathode (LiCoO2, LCO)/electrolyte (Li0.33La0.57TiO3, LLTO) half cells via SPS. Interdiffusion between Ti4+/Co3+was observed at the interface by SEM/STEM, resulting in the formation of the Li−Ti−La−Co−O and Li−Ti−Co−O phases in LLTO and the Li−Co−Ti−O phase in LCO. Computational modeling was performed to verify that the Li−Ti−Co−O phase has a LiTi2O4host lattice. In a study of interfacial electrical properties, the resistance of this interdiffusion layer was found to be 105 Ω, which is 40 times higher than the resistance of the individual LLTO phase. The formation of an interdiffusion layer is identified as the origin of the high interface resistance in the LLTO/LCO half‐cell.
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- Award ID(s):
- 1734763
- PAR ID:
- 10229077
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- ChemElectroChem
- Volume:
- 8
- Issue:
- 10
- ISSN:
- 2196-0216
- Format(s):
- Medium: X Size: p. 1847-1857
- Size(s):
- p. 1847-1857
- Sponsoring Org:
- National Science Foundation
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