Abstract
Lithium superionic conductors with the Li10GeP2S12 (LGPS)-type structure are promising materials for use as solid electrolytes in next-generation lithium batteries. A novel member of the LGPS family, Li9.42Si1.02P2.1S9.96O2.04, and its solid solutions were synthesised by quenching from 1273 K in the Li2S–P2S5–SiO2 pseudoternary system. The material exhibited an ionic conductivity as high as 3.2×10−4 S cm−1 at 298 K, as well as the high electrochemical stability to lithium metal, which was improved by the introduction of oxygen into the LGPS-type structure. An all-solid-state cell with a lithium metal anode and Li9.42Si1.02P2.1S9.96O2.04 as the separator showed excellent performance with a high coulomb efficiency of 100%. Thus, oxygen doping is an effective way of improving the electrochemical stability of LGPS-type structure.
Highlights
Lithium batteries have become pervasive in our daily lives, powering portable electronics and power tools, and are expected to play an important role in a vast range of energy storage applications, such as purely electric vehicles and power back-up devices, as well as the grid-level storage of renewably generated energy (Armand and Tarascon, 2008; Scrosati and Garche, 2010; Dunn et al, 2011)
We tested various synthesis conditions and found that the optimized mixing procedures and cooling rates are important for obtaining monophasic LSiPSO, the composition is more relevant with respect to the phase that appears in the samples
In the case of the compositions on the Li4SiS2O2–Li3PS4 tie line, the LSiPSO phase was not obtained as a pure phase; the main phases were a β-Li3PS4-derived phase in samples #2 and #3, a LSiPSO phase along with the Li7PS6 phase with an argyroditelike structure in sample #4, and a Si-based LGPS-type phase in sample #5 (Kong et al, 2010; Homma et al, 2011)
Summary
Lithium batteries have become pervasive in our daily lives, powering portable electronics and power tools, and are expected to play an important role in a vast range of energy storage applications, such as purely electric vehicles and power back-up devices, as well as the grid-level storage of renewably generated energy (Armand and Tarascon, 2008; Scrosati and Garche, 2010; Dunn et al, 2011). These advanced applications will inevitably require batteries that exhibit higher energy and power densities, as well as the ability to be scaled-up. The high ionic conductivity is attributable to the unique structure of LGPS, in which lithium ions are distributed along the c-axis in a three-dimensional framework composed of an octahedral LiS6 unit and tetrahedral PS4 and GeS4 units (Kwon et al, 2015; Wang et al, 2015)
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