New battery technologies are needed to overcome the limitations of current Li ion batteries (LIB) in terms of safety, energy density, and environmental/recycling issues. Due to the limited availability of Li and concerns about its recyclability, Na-ion batteries have been proposed as a potential alternative. Solid-state Na-ion batteries are a promising technology for increasing the energy density of batteries, a critical feature for many applications. However, several problems have plagued the development and use of solid-state batteries and have prevented the widespread use of this technology, in particular their low cyclability, i.e. the lack of stability of the battery after a few cycles. In this proposal, we characterize novel zero-excess solid-state Na-ion model batteries, a promising solution for solid-state batteries. We will perform PEEM experiments on the relevant core levels of the sample to obtain reliable information on the early stages of Na anode formation. The results will provide new critical information on the formation of the Na anode-solid electrolyte interface and the complex physicochemical phenomena that take place at the solid electrolyte surface region and their role in the stability of the battery cell.

The possibility to generate orbital angular momentum currents from charge currents is attracting a lot of interest in the research community. Several emerging phenomena associated to orbital currents have been investigated in the last few years, but experiments employing different techniques and materials have produced a widespread of results in terms of generation efficiency and diffusion lengths. Here we aim at employing x-ray synchrotron techniques to track changes in the electronic orbital occupation induced by electric currents in transition metals (TMs) such as Ti and Mn. This proposal builds up on our previous studies based on Cu/oxide interfaces where we detected, for the first time, the emergence of spectral shifts along the L3,2 absorption edges of Cu due to orbital angular momentum accumulation by XMCD-PEEM (experiments 2023027537 and 2024028319). However, the amplitude of the spectral shifts detected were smaller than expected according to our spin-orbit torques (SOTs) analysis and literature reports. In this proposal we aim at investigating Ti and Mn, two of the TMs most studied in the literature by diverse techniques (MOKE, EELS, SOTs) and compare with our results in Cu/oxide. We aim at clarifying the origin of the apparent discrepancies reported in the literature and confirm the orbital nature of the angular momentum detected in these materials upon the application of electric currents.

New battery technologies are required to overcome the limitations of current Li ion batteries (LIB) concerning safety, energy density and environmental/recycling issues [1]. Solid state batteries (SSBs) are considered particularly promising, owing to their intrinsic higher energy density, increased safety, and improved recyclability. In a SSB, the anode is made of Li metal, with a high theoretical capacity, and a large negative potential. However, the Li metal anodes are difficult to handle and the workability of thin Li foils results in high fabrication costs [2].In anode-less solid-state lithium batteries, also known as zero excess solid state batteries (ZESSBs), the anode is formed in situ at the interface between the solid state electrolyte (SSE) and the anode current collector (CC). ZESSBs have an improved energy density, increased safety, and a prolonged operation life [3], making them a potential option for next-generation energy storage devices, particularly in the mobile industry [4]. Here, we aim to develop novel preparation procedures of the model cells to modify the growth habit of the anodes The objective of this project is to study and understand the modification of Li anodes nucleation and growth mode by using an interlayer between the SSE and the CC. The presence of an interlayer during the first plating will permit tuning the balance between the growth mechanisms to a regime where the Li atoms coming from the electrochemical current relax preferentially via wetting and alloying. Employing this novel approach we expect that Li storage in a ZESSB can be safely improved, and long-lasting cells with strong mechanical stability can be obtained.