Mechanism of the Electrochemical Insertion of Lithium into LiMn2 O 4 Spinels

Abstract

LiMn2O4-based spinels have been extensively studied as positive electrode materials for lithium-ion batteries. Our investigations have shown that, by using the Pechini process, the performance of these materials can be improved significantly through adjustments to the synthesis conditions and composition by means of selective doping. This paper reports the results of neutron and ex situ X-ray diffraction studies performed to examine the structural changes that occur during lithium ion insertion into various LiMn,O4 compositions. It appears that an ordering intercalation of lithium ions occurs in the lithium concentration range of 0.15-0.35, followed by a second-order phase transformation when the lithium population is close to 0.5, leading to a random lithium insertion into a single-spinel phase from x = 0.5 to 1.0. * Electrochemical Society Student Member. * * Electrochemical Society Active Member.agreement with many literature reports,4"°13 including results obtained from the ionic modeling of various lithium manganese spinel compounds.'3 However, the reason is not cleat One goal of this study was to explore the intrin-

Structural stability in partially substituted lithium manganese spinel oxide cathode

“…This difference indicates a distortion of octahedron arising from adjacent M 4+ and M 3+ cation pair that has large difference of ionic radii. Moreover, the difference of the bond angle (or) and (13) in LiM_n3+Mn4+O 4 (~ct = 6.603 ~ is larger than that in LiCP+Mn4+O 4 (13-r = 6.227~ Accordingly it will be concluded that Cr 3+ substitution for Mn 3+ leads to the decrease of the local distortion of octahedron M3+O6. We confirmed similar observations several times using different MD cell.…”

Electrochemical and structural comparison of zinc-cobalt doped spinels with other doped lithium manganese spinels

“…Especially, the second peak in each differential capacity curve is quite sharp. This feature is commonly known as a hint for the coexistence of two cubic spinel phases in the higher potential range [27]. For the higher Zn-Co doped and the higher Co doped spinel, this second peak is remarkably lowered and broadened.…”

A new method of pretreatment of lithium manganese spinels and high-rate electrochemical performance of Li[Li0.033Mn1.967]O4

“…Careful electrochemical, X-ray and neutron diffraction studies have shown that the charge/discharge process occurs in three steps, hence up to three phases coexist in the 0 B x B 1 range [7][8][9]. The structure of Li 0.5 Mn 2 O 4 has been determined as belonging to the modulated R 3m space group, Z = 6, with the O 2- …”