A New Three‐Volt Spinel Li1 + x Mn1.5Ni0.5 O 4 for Secondary Lithium Batteries

Abstract

The spinel LiMn1.5Ni0.5O4 has been prepared at low temperature using a new sol‐gel process. X‐ray diffraction analysis reveals that the obtained material presents a cubic spinel structure with a unit cell parameter lower than that of stoichiometric LiMn2O4 . X‐ray photoelectron spectroscopy confirms the divalent state of doped nickel in the material. Furthermore, LiMn1.5Ni0.5O4 compound can intercalate a second lithium both chemically and electrochemically, leading to the formation of a new Li2Mn1.5Ni0.5O4 material with the same cubic spinel structure. This material presents only one plateau at around 3 V vs. normalLi/Li+ with a large discharge capacity of 160 mAh/g and fairly good cyclability. This result is in contrast to the undoped Li2Mn2O4 , where two plateaus at 4 and 3 V are observed because of the occurrence of a structural transition caused by the Jahn‐Teller effect. The structure and the electrochemical behavior of Li1+xMn1.5Ni0.5O4 are investigated and compared to those of LiMn1.5Fe0.5O4 material prepared by the same sol‐gel process.

The Lattice Compatibility Theory: Supports from the Generalized Simha-Somcynsky Chemical Physics-Related Theory

“…It was recorded that these trends are not the same for Co 2+ and Co 3+ ions. The loss of stability which characterized the transition from Co(II) to Co(III) state and which was recorded by Amine et al [27,28], Duncan et al [29], Liu et al [30], Santhanam and Rambabu [31], and Aklalouch et al [32,33] has been satisfactorily explained in the Lattice Compatibility Theory (LCT) framework. The most probable explanation which can be provided through the Simha-Somcynsky theory lies in the expression of the Helmholtz free energy (see (3) and (7)).…”

Comparison of Different Synthesis Methods for LiNi0.5Mn1.5O4—Influence on Battery Cycling Performance, Degradation, and Aging

“…Over the years,alarge varietyo fm ethods have been reported to synthesize LNMO.T he majority of these synthesis methods can be divided into those based on wet chemistry, which imply the formationo faprecursor in as olution (e.g., co-precipitation, [4,[15][16][17][18][19] sol-gelm ethod, [20][21][22][23] modifiedP echini method, [24][25][26] emulsion drying [27][28][29] ), and solid-state methods in which the reactants are heat-treated directly after mixing (e.g.,c ombinational annealingm ethod, [30,31] one-step solidstate method [32][33][34] ). Although the wet-chemistry methods are able to produce powders of high chemical homogeneity with an arrow size distribution at low annealingt emperatures, [3,15] the synthesis procedures are rather complex and costly because of the long processing times and expensive precursor materials required.…”

Surface stability of spinel MgNi0.5Mn1.5O4 and MgMn2O4 as cathode materials for magnesium ion batteries

“…Among them doping with Ni could make the spinel structure LMO more stable, thus improving the circulation characteristics of the LIBs [16,17]. Amine et al [18] reported that the LiNi 0.5 Mn 1.5 O 4 (LNMO) used as the cathode material for LIBs presented high discharge capacity and good cyclic reversibility.…”