Effects of excess Li on the structure and electrochemical performance of Li1+ zMnTiO4+ δ cathode for Li-ion batteries

Abstract

Spinel-based LiMn2O4 is the most attractive cathode for Li-ion battery due to high voltage, low cost, and non- toxicity. The cycle life of the spinel cathodes could be improved by replacing Mn4+ with Ti4+ leading to the formation of new spinel cathode, LiMnTiO4. However, its application is restricted due to the associated loss in the specific capacity. In this work, spinel-layered Li1+zMnTiO4+delta (z = 0, 0.5, and 1.0; delta is the value to reflect the composite character of the material) cathodes were fabricated to achieve long cycle life, without compromising on the specific capacity. Cathodes with excess Li (z = 0.5 and 1.0) formed a spinel- layered composite structure with notation (1-alpha) LiMn(2-x)TixO(4).aLi(2)Mn(y)Ti(1-y)O(3) [y = 0.5-(( 1/alpha - 1) (1 - x))]. These cathodes exhibited an enhanced specific capacity of similar to 218 mAh g (1) (20% higher), with a capacity retention of 94% after 60 cycles. The structural and electrochemical properties of these cathodes were investigated using X- ray diffraction, galvanostatic cycling, cyclic voltammetry, and the galvanostatic intermittent titration technique to understand the mechanisms underlying the enhanced capacity and cycle stability. The effect of the Li- rich layered phase on the electrochemical performance of the Li1+ zMnTiO4+ delta cathodes was also investigated. (C) 2016 Elsevier Ltd. All rights reserved.