High energy mechano-chemical milling: Convenient approach to synthesis of LiMn1.5Ni0.5O4 high voltage cathode for lithium ion batteries

Nanostructured high voltage spinel phase of LiMn1.5Ni0.5O4 (LMNO) of particle size ∼10-40 nm has been synthesized by a cost effective high energy mechanical milling (HEMM) approach followed by low temperature thermal treatments. High energy mechanical milling of lithium and manganese oxide precursors followed by moderate heat treatment results in the formation of single phase of LMNO, the high voltage spinel phase. The nanostructured LMNO has been studied as a high voltage cathode for lithium ion rechargeable batteries. Cyclic voltammetry as well as the differential capacity plots of nanostructured LMNO show the occurrence of two major reversible reactions occurring in the potential window of ∼2-3.6 V and ∼3.6-5.1 V with an associated specific capacity ∼105 mAh/g and ∼128 mAh/g, respectively. The nanostructured LMNO synthesized by the HEMM process followed by thermal treatments at ∼773 K, ∼873 K and ∼973 K shows a reversible capacity ∼120-110 mAh/g when cycled at a rate of ∼20 mA/g (∼C/6) in the potential window ∼3.6-5.1 V. Furthermore, the nanostructured HEMM derived LMNO shows a moderate rate capability with a capacity retention ∼87 mAh/g when cycled at ∼80 mA/g (∼C) rate.