Electrospun spinel-structured high-entropy oxide nanofibers as fillers for solid polymer electrolytes: The pivotal role of oxygen vacancies

Solid composite electrolytes (SCEs) have great potential in improving the safety of lithium-ion batteries. We have recently shown that the high-entropy oxide (HEO) nanoparticles and nanofibers can be successfully used as passive fillers for the preparation of composite polyethylene oxide (PEO)/HEO SCEs. The main aim of this contribution is to shed light on the role and nature of defects present on the HEO surface and how their density influences the SCE electrochemical performance.