Dual Doping: An Effective Method to Enhance the Electrochemical Properties of Li₁₀GeP₂S₁₂‐Based Solid Electrolytes

Abstract

Multiple doping is widely used to improve the performance of a material, including its electrical transport, mechanical, and photovoltaic properties. In this paper, Sn-Se dual-doped Li 10 GeP 2 S 12 (LGPS, thio-LISICON II analogue) electrolytes were synthesized via ball milling and sintering and compared with those Sn or Se single-doped. Successful Sn and/or Se substitution expanded the unit cell and formed SnSe 4À 4 units, which were verified by X-ray powder diffraction, energy-dispersive X-ray spectroscopy, and Raman spectroscopy. In contrast to the limited benefits of Se single doping and the negative effects of Sn single doping, Sn-Se dual doping demonstrated up to 53% enhancement in ionic conductivity. More importantly, Sn-Se dual-doped LGPS showed an extremely low activation energy of 16 kJ/mol, which is one of the lowest known values for lithium ion conductors; as well as one of the widest electrochemical windows of 8 V. Sn-Se dual-doped LGPS is a promising electrolyte for advanced all-solid-state batteries.

Li10GeP2S12‐Type Superionic Conductors: Synthesis, Structure, and Ionic Transportation

“…Furthermore, partial substation of sulfur by selenium was also reported for the Li–Ge–Sn–P–S system. [ 68 ] These examples indicate that there are still numerous opportunities to control the properties of LGPS‐type phases owing to the ability of LGPS to function as a structural template.…”

Electrolytes for Li-ion all-solid-state batteries: a first-principles comparative study of Li10GeP2O12 and Li10GeP2S12 in the LISICON and LGPS phases

“…LGPS has been extensively studied so far, both experimentally [79,80,83,89,90,92,101,104,168,169] and theoretically [93-96, 99, 100, 124, 170, 171], in its highly conductive tetragonal phase (space group P 4 2 /nmc, σ = 1.2×10 −2 Scm −1 at room temperature [78], here denoted t-LGPS), but it is known from experiments to exist also in a monoclinic allotrope (space group P 2 1 /m, here denoted o-…”

“…In an additional effort to improve conductivity, a new phase (tetragonal, space group P 4 2 /nmc, #137) of thio-LISICONs at the composition x = 0.67 (named thereafter LGPS) was discovered in 2011 [78], with a record conductivity of 12 × 10 −3 Scm −1 . This inspired a new wave of efforts, both experimental [79][80][81][82][83][84][85][86][87][88][89][90][91][92] and theoretical [93][94][95][96][97][98][99][100][101], aiming to understand conduction mechanisms and to push the ionic conductivity even further. By tuning lithium, germanium and phosphorus compositions, a room-temperature conductivity of 14.2 × 10 −3 Scm −1 was reached [89], and by substituting germanium with silicon and simultaneously partially replacing sulphur with chlorine a value of 25 × 10 −3 Scm −1 was obtained [91].…”

Controllable Li3PS4–Li4SnS4 solid electrolytes with affordable conductor and high conductivity for solid‐state battery

“…However, the intensity of the peaks at 418 and 430 cm −1 significantly declined when x = 1.7, probably owing to the transformation of different structural sites of PS 4 3− tetrahedron. 17,[28][29][30][31][32] It indicated that PS 4 3− units were easily formed at x = 1.5 and linked to restructure after further addition. As exhibited in Figure 2B, the Raman spectrum of LiSn(Ge)PS was almost consistent with previous reports.…”