ИСТИНА

The main reason preventing commercialization of rechargeable lithium metal batteries since they have been proposed in the middle of 80-s arises in connection with the a high propensity to form Li dendrites (tree-like structures) at the anode upon repeated charges/discharges processes resulted in internal short-circuiting and a low Coulombic efficiency (CE) connected with a short cycle life. The mechanism of dendrite initiation and propagation can be explained in terms of The Chazalviel electromigration-limited model. Based on its results the dendrite suppression can be achieved using electrolyte with high ionic conductivity and a Li+ transference number (tLi+) close to unity[4]. High shear modulus is also an important property for a functional electrolyte to suppress the Li dendrite growth. On this basis our research group suggested using polymer electrolyte systems with solid-state Li-ion conductor Nafion dopped with Li+ ions in the form of thin film (117����m) in the pair with conventional bi-ionic liquid electrolyte (LE) PC, where Li-Nafion can serve an ideal material to protect Li against dendrite penetration according to its unityt tLi+ and high mechanical strength. This special designed electrochemical cell operates at room temperature conditions in contrast to other polymer electrolyte systems (with working temperature of about 60-800C) [5,6]. The development of dendrite suppression methods requires a detailed examination of solid electrolyte forming interface and Li-dendrite growth processes on Li-metal anode. Next aim is to realize Li-metal anode in-operando Neutron reflectometry (NR) measurements of the thin film interfacial SEI (solid electrolyte interface) layer and dendrite formation as function of potential in a working lithium special designed cell and to focus on NR diagnostic of the operating Li-Nafion polymer system under cycling conditions. NR determines the depth profile of the scattering length density (SLD) which is related to composition, by fitting the intensity of reflected neutrons as a function of grazing angle from the surface, θ, providing sub-Ångström precision of features greater than ∼1.5 nm in thickness.