阳极
电解质
锂(药物)
材料科学
硅
介电谱
X射线光电子能谱
化学工程
无机化学
分析化学(期刊)
电极
化学
冶金
电化学
物理化学
内分泌学
工程类
医学
色谱法
作者
Luise M. Riegger,Svenja‐K. Otto,Marcel Sadowski,Sven Jovanovic,Olaf Kötz,Sascha Harm,Lucas G. Balzat,Steffen Merz,Simon Burkhardt,Felix H. Richter,Joachim Sann,Rüdiger‐A. Eichel,Bettina V. Lotsch,Josef Granwehr,Karsten Albe,Jürgen Janek
标识
DOI:10.1021/acs.chemmater.1c04302
摘要
Thiophosphate solid electrolytes containing metalloid ions such as silicon or germanium show a very high lithium-ion conductivity and the potential to enable solid-state batteries (SSBs). While the lithium metal anode (LMA) is necessary to achieve specific energies competitive with liquid lithium-ion batteries (LIBs), it is also well known that most of the metalloid ions used in promising thiophosphate solid electrolytes are reduced in contact with an LMA. This reduction reaction and its products formed at the solid electrolyte|LMA interface can compromise the performance of an SSB due to impedance growth. To study the reduction of these metalloid ions and their impact more closely, we used the recently synthesized Li7SiPS8 as a member of the tetragonal Li10GeP2S12 (LGPS) family. Stripping/plating experiments and the temporal evolution of the impedance of symmetric Li|Li7SiPS8|Li transference cells show a severe increase in cell resistance. We characterize the reduction of Li7SiPS8 after lithium deposition with in situ X-ray photoelectron spectroscopy, time-of-flight secondary-ion mass spectrometry, and solid-state nuclear magnetic resonance spectroscopy. The results indicate a continuous reaction without the formation of elemental silicon. For elucidating the reaction pathways, density functional theory calculations are conducted followed by ab initio molecular dynamics simulations to study the interface evolution at finite temperature. The resulting electronic density of states confirms that no elemental silicon is formed during the decomposition. Our study reveals that Li7SiPS8 cannot be used in direct contact with the LMA, even though it is a promising candidate as both a separator and a catholyte material in SSBs.
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