Electrophoretically co-deposited Li4Ti5O12/reduced graphene oxide nanolayered composites for high-performance battery application

Abstract

Achieving aggregation-free nanocomposites is a challenge for the conventional casting process in Li-ion battery electrode fabrication, which leads to inhomogeneous dispersion of active and conductive components – a property which further accelerates, or triggers, battery degradation. This becomes even more challenging when using 2D nanomaterials. In this paper, electrophoretic deposition (EPD) is used to fabricate nanolayered composite anodes composed of spinel lithium titanate (LTO) and reduced graphene oxide (rGO). First, the electrode material precursors, 2D-lithium titanate hydrate (LTH) and graphene oxide nanosheets, are formulated into a stable colloidal suspension and electrophoretically co-deposited (EPD) onto copper substrate. Subsequently, the binder-free deposits are annealed at 600 ​°C in a 5% hydrogen environment for 6 ​h to induce in-situ topotactic transformation of the precursors into LTO/rGO nanolayered composites. Comparing to their PVDF-built electrodes, the EPD nanolayered composites exhibit robust electrochemical performance in terms of power capability, cyclability and impedance control. This performance enhancement is due to a well-established graphene oxide-based percolation network for both electronic and ionic conduction engineered with the help of EPD. Therefore, the local deep discharge to lower state-of-charges is avoided, hence avoiding the serious capacity fade from which nano-LTO suffers. Through this research, EPD casting technology presents itself as superior mesoscale construction strategy for nanostructured LIB electrodes.