Synthesis, Characterization, and Electrochemical Cycling Behavior of the Ru-Doped Spinel, Li[Mn[sub 2−x]Ru[sub x]]O[sub 4] (x=0, 0.1, and 0.25)

Abstract

Pure and Ru-doped Li[Mn2−xRux]normalO4 ( x=0.1 and 0.25) spinel compounds are prepared by the high temperature solid-state reaction and characterized by X-ray diffraction (XRD), scanning electron microscopy, Brunauer, Emmett, and Teller surface area, density, IR, Raman spectroscopy, and X-ray absorption spectroscopy. XRD studies show single-phase compounds with the cubic spinel structure and a decrease in (Mn–O) and an increase in (Li–O) bond lengths on Ru doping. The electrochemical cycling behavior of Li[Mn2−xRux]normalO4 is examined by galvanostatic cycling and cyclic voltammetry (CV). The CV shows that the normalMn3+↔normalMn4+ couple lies in the range from ∼4.0to∼4.2V and the spinel-to-double-hexagonal (S-DH) transition at ∼4.5V in agreement with results in the literature. The normalRu4+↔normalRu5+ redox couple operates at ∼4.3V vs Li in the spinel structure. The S-DH phase transition is suppressed on Ru doping. Charge–discharge cycling, up to 25 or 40cycles , in the voltage ranges 3.5–4.3 and 3.5–4.6V vs Li at 0.14C rate gave initial charge capacities ranging from 118to139mAhnormalg−1 for various x . Compositions with x=0.1 and 0.25 showed smaller initial capacity loss and smaller capacity fading during cycling as compared to x=0 . For x=0.25 in the voltage range 3.5–4.6V and 2–25cycles , the capacity fade is only 9% thereby showing the beneficial effect of Ru doping, by way of suppression of S-DH transition, participation of Ru-redox couple, and better electronic conductivity of the compound during cycling, in comparison to pure LinormalMn2normalO4 .

Solution combustion synthesis of LiMn2O4 fine powders for lithium ion batteries

“…The CVs show a slight shift of the oxidation and reduction peaks and reduced peak area upon cycling, indicating a change in the surface structure and composition of the spinel electrode and a minor decrease in the discharge capacity, as confirmed by the charge-discharge cycling test discussed above. [23] Figure 8-(b) provides the comparison between the initial CVs of the samples calcined at different temperatures. The CV curves exhibit a couple of distinct redox peaks, which indicate the two-stage Li + extraction/insertion from/into the spinel phase and are consistent with the two-plateaus detected in the charge/discharge profiles discussed above.…”

Synthesis of compounds, Li(MMn11/6)O4 (M=Mn1/6, Co1/6, (Co1/12Cr1/12), (Co1/12Al1/12), (Cr1/12Al1/12)) by polymer precursor method and its electrochemical performance for lithium-ion batteries

“…Cyclic voltammetry (CV) studies were carried out with Macpile instrument (Biologic, France) and the galvanostatic studies were carried out with Bitrode battery tester (Model SCN, Bitrode, USA) with different current rates of 0.25, 1, 2 and 5C in the voltage range of 3.5-4.3 V at room temperature (24 • C). The C rates were calculated based on the attainable capacity (120 mAh g −1 ) of the compound LiMn 2 O 4 in the voltage range of 3.5-4.3 V [35,36]. Thickness of the electrodes was ∼20 m and geometrical area of the electrode used was 2 cm 2 .…”

“…Many reports have emphasized on the influence of the nanosized particles on the better electrochemical performance of LiMn 2 O 4 [3,4,[28][29][30]. In addition to bare LiMn 2 O 4 , studies on different doping elements like Co, Cr, Al, Ni, Fe, Ru, etc., are reported in literatures [19,[31][32][33][34][35][36]. In the present work, nanoand submicron sized bare and doped LiMn 2 O 4 compounds have been prepared by means of polymer precursor method using the polymer, polyvinylpyrrolidone (PVP) under similar preparation conditions.…”

A Review on Nanocomposite Materials for Rechargeable Li-ion Batteries

“…Li and Al co-doped manganese oxide spinel compounds prepared by polyvinyl pyrrolidone precursor method improved the initial discharge capacity and capacity retention [88]. LiMn 2 O 4 /CNT composites are also reported with improved capacity retention and high rate capability for flexible electronics applications [84] [88][89][90][91][92][93][94]. LiMn 2 O 4 prepared by the one-pot molten salt method resulted in nano sized (~50 nm) hollow spherical particles which showed improved capacity retention even at high C-rates (i.e., 96% retention at 5C rate) [89].…”

“…These nano sized spherical LiMn 2 O 4 particles were also performed well at 50 • C which was associated with their high crystallinity and the presence of spherical particles [89]. In another study, Ru doped LiMn 2−x Ru x O 4 (x = 0.1 and 0.25) was shown to reduce the capacity fading as compared to undoped sample by mitigating the spinel-to-double-hexagonal transition at 4.5 V, and due to the presence of Ru 4+ ↔ Ru 5+ redox couple and better electronic conductivity of the Ru doped samples [92]. The other dopants studied for LiMn 2 …”