Lithium titanate-based anode materials

Abstract

Graphitic carbon is the most widely used anode material in commercial Li-ion batteries due to its low lithiation potential, long cycle life, abundant resources and low cost. However, Li-ion batteries using graphite as anode material give rise to rate, safety and life problems. During lithium intercalation/deintercalation process, graphite undergoes a considerable volume change (*10% [1]), which could cause particle cracking and even peeling off of anode film from the current collector, leading to gradual capacity degradation of the electrode [2, 3]. Safety concerns arise when the cells experience fast charging, long-term cycling, or low temperature charging owing to the propensity of formation of lithium dendrites, which is induced by the low lithiation potential of the graphite anode (close to 0 V vs. Li/Li+) and the low lithium ion diffusivity in the graphite lattice [4, 5]. As an alternative anode material to carbon, Li4Ti5O12 has been extensively studied for the potential use in large-scale Li-ion batteries. Li4Ti5O12 shows stable charge/discharge platform at ca. 1.55 V versus Li/Li+, and possesses excellent cycling stability and unique safety characteristic owing to its negligible volume change and high redox potential upon Li-ion intercalation/deintercalation. However, coarse Li4Ti5O12 exhibits poor rate performance because of its low electronic conductivity and sluggish lithium ion diffusivity [6, 7]. In some cases, especially when aging at elevated temperature or cycling in a long-term regime, gas generation frequently occurs in Li4Ti5O12-based batteries [8]. In past decades, many efforts have been devoted to overcoming these problems and significant advancements have been achieved, which make Li4Ti5O12 viable for practical application in batteries for various electrical energy storage, such as electric/hybrid electric/plug-in hybrid electric vehicles (EV/HEV/PHEV), grid load leveling, integration of renewable energy sources, etc.