Electrochemical behaviour of Sn and Sn-C composite electrodes in LiBOB containing electrolytes

The electrochemical behaviour of Sn electrodes in lithium bis(oxalate)borate (LiBOB)-based electrolyte Li-ion cells is studied by using a carbon-free electrodeposited Sn electrode and a nano-structured Sn-C composite electrode. Cyclic voltammetry, galvanostatic cycling tests, and potentiostatic impedance spectroscopy demonstrate that the presence of carbon promotes the decomposition of the LiBOB-based electrolyte starting at a voltage value of around 1.75 V vs. Li/Li+. The LiBOB electrolyte decomposition is probably associated with the formation of a high electrode-electrolyte interphase impedance which limits the rate capability. A reduction of the overall impedance and an increase of the electrode rate capability can be achieved by using a pre-treated (pre-lithiated) Sn-C electrode. It is shown that the pre-treatment also reduces the irreversible capacity of the Sn-C electrode and allows to successfully assemble full Li-ion cells.