Effect of structure on the storage characteristics of manganese oxide electrode materials

Abstract

Eleven types of manganese-containing electrode materials were subjected to longterm storage at 55°C in 1M LiPF 6 ethylene carbonate/dimethyl carbonate (EC/DMC) solutions. The amount of manganese dissolution observed depended upon the sample surface area, the average Mn oxidation state, the structure, and substitution levels of the manganese oxide. In some cases, structural changes such as solvate formation were exacerbated by the high temperature storage, and contributed to capacity fading upon cycling even in the absence of significant Mn dissolution. The most stable materials appear to be Ti-substituted tunnel structures and mixed metal layered oxides with Mn in the +4 oxidation state.

Compatibility of Li[sub x]Ti[sub y]Mn[sub 1−y]O[sub 2] (y=0, 0.11) Electrode Materials with Pyrrolidinium-Based Ionic Liquid Electrolyte Systems

“…Under similar conditions, little to no capacity fading is seen in Li/Li x MnO 2 cells with conventional LiPF 6 -based solutions at room temperature but some losses are observed at 55°C due to disproportionation and dissolution of Mn from the cathode. 33 Scanning electron micrographs and XRD patterns on fresh and cycled Li x MnO 2 electrodes recovered from lithium cells are presented in Fig. 11.…”

Electrode Materials with the Na0.44MnO2 Structure: Effect of Titanium Substitution on Physical and Electrochemical Properties

“…As with other types of manganese-containing electrodes, however, some dissolution of manganese is observed when 2 cells are cycled in LiPF 6 -containing electrolytic solutions at 55°C, causing degradation of the electrode material. 5 For higher energy applications such as plug-in hybrid electric vehicles (PHEVs), the limited specific capacity (~120 mAh/g) achievable in conventional cells is also an issue. The low oxidative stability limit of carbonate-based electrolytes (4.3-4.4 V vs.…”

Phase evolution and Sn-substitution in LiMn2O4 thin films prepared by pulsed laser deposition

“…Spinel LiMn 2 O 4 has been reported to possess specific advantages of its low internal resistance, long cycle life, fast charging time, high cell voltage, high load current, and high thermal stability as a cathode material for lithium-ion batteries [1][2][3][4][5][6][7]. Particularly, sustaining the internal cell resistance at low levels is the key to obtaining a high rate-capability that has been required for the fastcharging and high-current discharging.…”

“…Many studies were investigated to avoid the unwanted phase transition by adopting unusual dopings or substitutions including transition metals, such as Ti, Cr, Co and Ni, and other elements, i.e., Mg and Al [4][5][6][7][8][9]. As an alternative choice, the substitution of heavy elements like W and Er were also studied with limited success due to their relatively large atomic or ionic size [10,11].…”