Probing lithium mobility at a solid electrolyte surface

Abstract

Solid-state electrolytes overcome many challenges of present-day lithium ion batteries, such as safety hazards and dendrite formation1,2. However, detailed understanding of the involved lithium dynamics is missing due to a lack of in operando measurements with chemical and interfacial specificity. Here we investigate a prototypical solid-state electrolyte using linear and nonlinear extreme-ultraviolet spectroscopies. Leveraging the surface sensitivity of extreme-ultraviolet-second-harmonic-generation spectroscopy, we obtained a direct spectral signature of surface lithium ions, showing a distinct blueshift relative to bulk absorption spectra. First-principles simulations attributed the shift to transitions from the lithium 1 s state to hybridized Li-s/Ti-d orbitals at the surface. Our calculations further suggest a reduction in lithium interfacial mobility due to suppressed low-frequency rattling modes, which is the fundamental origin of the large interfacial resistance in this material. Our findings pave the way for new optimization strategies to develop these electrochemical devices via interfacial engineering of lithium ions.

Eliminating Li Dendrites in PEO-Based Polymer Solid Electrolytes by Doping with SbF3

“…The low self-diffusion of Li on the bulk and the localized high current density lead to the preferential deposition of Li + on surface defects of the bare Li electrode. These ions accumulate during cycling, resulting in uneven plating and stripping (Figure g, h). , Consequently, Li dendrites emerge and penetrate the solid electrolyte, causing short circuits and a sudden drop in the voltage during cycling (insets of Figure c). The presence of a unique interface layer plays a crucial role in reducing interfacial resistance and hindering the growth of Li dendrites by maintaining a uniform distribution of Li + at the interface (Figure g, h).…”

Spatial Distance Effect of Negative Ion–Porous Organic Polymers on the Electrochemical Properties of Composite Solid Electrolytes

“…However, energy storage technology still faces numerous challenges. Lithium-ion batteries (LMBs) have been widely explored because of their long service life and excellent energy storage performance. − However, traditional commercial liquid electrolyte lithium batteries have many safety risks, such as flammability and explosiveness, and these problems hinder the further development of lithium batteries. − Compared with liquid electrolytes, solid-state electrolytes (SSEs) exhibit excellent chemical stability and safety properties . Among them, PEO, polyvinylidene fluoride (PVDF), and other polymer electrolytes have good contact between the lithium anode and the cathode, as well as high mechanical strength and good flexibility .…”