Reconstruction and electronic properties of β-Li3PS4 |Li2S interface

The morphology and properties of the interface between solid electrolyte and electrode have important impacts on all-solid-state lithium-sulfur batteries’ performance. We used the first-principles calculations to explore the interface between Li2S cathode and β-Li3PS4 (lithium thiophosphate, LPS) solid electrolyte, including lattice structure, mechanical, electrical properties, interface contact type, and charge distribution in real space. It is found that the interface is significantly reconstructed, and the Li atoms at the interface move mainly parallel to the interface plane. The interface density states introduce metallic properties, mainly contributed by the Li-s and S-s, -p orbitals in Li2S and S-p orbitals in LPS. The highest occupied molecular orbitals of the LPS electrolyte are lower than the electrochemical potential (Fermi level) of the Li2S cathode, thus the electrolyte and cathode materials are reasonable and stable in thermodynamics. Interface density of states shows electrons on the interface do not penetrate from Li2S into LPS, and do not leak electrons to cause electron conduct in LPS. Besides, the interface is an n-type Schottky barrier with a barrier value of 1.0 eV. The work-function of the interface indicates that there is a space charge layer by the redistribution of electrons, which is in agreement with the result of interface charge density difference. The electron/hole pairs will be separate, realizing high current charge and discharge capability because of the space charge layer.

Nature of the surface space charge layer on undoped SrTiO3 (001)

Chemically stable SrO1+x surface oxide with c(6×2) superstructure is formed, creating space charge layer and surface band bending effects on undoped SrTiO3 (001), under elevated oxygen pressure and temperature conditions.

In-situ visualization of the space-charge-layer effect on interfacial lithium-ion transport in all-solid-state batteries

The space charge layer (SCL) is generally considered one of the origins of the sluggish interfacial lithium-ion transport in all-solid-state lithium-ion batteries (ASSLIBs). However, in-situ visualization of the SCL effect on the interfacial lithium-ion transport in sulfide-based ASSLIBs is still a great challenge. Here, we directly observe the electrode/electrolyte interface lithium-ion accumulation resulting from the SCL by investigating the net-charge-density distribution across the high-voltage LiCoO2/argyrodite Li6PS5Cl interface using the in-situ differential phase contrast scanning transmission electron microscopy (DPC-STEM) technique. Moreover, we further demonstrate a built-in electric field and chemical potential coupling strategy to reduce the SCL formation and boost lithium-ion transport across the electrode/electrolyte interface by the in-situ DPC-STEM technique and finite element method simulations. Our findings will strikingly advance the fundamental scientific understanding of the SCL mechanism in ASSLIBs and shed light on rational electrode/electrolyte interface design for high-rate performance ASSLIBs.