Spherical core-shell Li[(Li0.05Mn0.95)0.8(Ni0.25Mn0.75)0.2]2O4 spinels as high performance cathodes for lithium batteries

Abstract

Spinel-type, lithium manganese oxides, e.g.LiMn₂O₄, are very appealing electrodes for upgrading lithium batteries in terms of cost and environmental compatibility. Unfortunately, the practical use of these oxides has so far been hindered by some drawbacks, the most serious being the short life associated with the severe capacity fading on cycling, especially experienced at temperatures above ambient. In this work we report a new strategy for tackling this issue. The results reported here demonstrate that our approach, based on innovative core-shell electrode morphology, is very effective in improving the behaviour of lithium manganese spinel electrodes in lithium cells, by ensuring exceptional capacity stability upon cycling in temperature ranges where all the previous manganese based electrode materials inevitably failed. We show that our core-shell electrodes deliver a specific capacity of the order of 85 mAh g⁻¹ in range of 3–4.3 V vs.Li/Li⁺ with a retention of 97% over 100 cycles at 60 °C . To our knowledge, such high performance levels have not been met so far.