The project proposal InFluENCE aims at improving the fundamental understanding and control of interfaces of a battery type based on Li-ion and Na-ion active materials: semi solid flow batteries (SSFB). The fact that the case study will be a SSFB set-up instead of classic lithium ion batteries is an asset, given that the methods and techniques developed are generic and could as well be implemented for conventional Li- and Na-ion systems for the techniques that are not concentrated on flow aspects.A main objective is the investigation and optimization of the interfaces developing between the electrolyte and the electrochemically active material particles in fluid electrodes. The acquired knowledge would allow the chemical and morphological optimization of active materials as well as the design of optimized interfacial layers (also called artificial Solid Electrolyte Interfaces, art-SEI) capable of warrant stable interfaces.A second main objective is the understanding and control the mechanical and conductive behaviours of the slurries. For this, it is necessary to determine the role of shape anisotropy and the overall nature (attractive or repulsive) of the short ranged interactions of the active materials besides the strength of the attractive forces for conductive nano-particles. The cross interaction should allow intimate contact between active material and the conductive particles.The experimental work is accompanied by thorough modelling to understand the physical phenomena occurring at the microscopic scale, to derive scaling rules towards macro-scale and to enable design recommendations leading to optimal interface behaviour (size of anodic and cathodic compartments, geometry of collectors, etc.).