Improved Electrochemical Properties of Li4Ti5O12 Nanopowders (NPs) via Addition of LiAlO2 and Li6SiON Polymer Electrolytes, Derived from Agricultural Waste

Abstract

Li4Ti5O12 (LTO) has received considerable interest as an alternate anode material for high power density batteries for large scale applications. However, LTO suffers from poor Li+ diffusivity and poor electronic conductivity, resulting in capacity loss and poor rate performance. Here we demonstrate a facile synthesis of LTO NPs using liquid-feed flame spray pyrolysis (LF-FSP) which provides high surface area (∼38 m2/g) spinel structure LTO NPs with average particle sizes (APSs) of 45 ± 0.3 nm. Pristine LTO-Li half-cells exhibit reversible capacity of 70 mAh/g at 10 C. In this study, we show that mixing LiAlO2 NPs (5 wt %) and Li6SiON polymer precursor (10 wt %) with pristine LTO via ball-milling and ultrasonication followed by tape casting enhances the LTO rate performance providing reversible capacity of ∼217 mAh/g at 5 C over 500 cycles. The Li6SiON polymer electrolyte is synthesized from rice hull ash (RHA), an agricultural waste, providing a green synthetic approach to electrode coating materials. CV and EIS studies indicate that adding the solid and polymer electrolytes reduces charge-transfer resistance and electrode polarization, enhancing both reversibility and the LTO Li+ diffusion coefficient from 4.6 × 10–14 to 2.7 × 10–12 cm2/s.