Effects of Lithium Content and Surface Area on the Electrochemical Performance of Li_1.2Mn_0.54Ni_0.13Co_0.13O₂

Abstract

Lithium-rich, layered composites of xLi 2 MnO 3 •(1-x)LiNi 1/3 Mn 1/3 Co 1/3 O 2 have been extensively studied for PHEVs and EVs. To ensure complete lithiation, most synthesis methods require the addition of excess lithium compared to the stoichiometric composition. In this study lithium enriched, layered composites of Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 were synthesized in a spray pyrolysis process. Spray pyrolysis allows for excellent control of composition and in this work the lithium content was systematically varied between 3.3 wt% excess and 3.3 wt% deficient compared to Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 . The as-synthesized powders were annealed at 900 • C for 2, 5 and 20 hours. Results indicate that as the annealing time is increased the surface areas is reduced from 9 to ∼2 m 2 g −1 .No new phases form during the annealing process although changes in the relative intensity of the ( 018) and ( 110) peaks imply a reorganization between the transition metal and lithium layers. An excess Li of 3.3 wt% is sufficient to counter these structural rearrangements and maintain discharge capacities close to 200 mAhg −1 after 100 cycles at C/3. Samples with a smaller surface area do not lead to improved capacity retention. The results also suggest that the Li 2 MnO 3 structural component has a key role in the voltage fade for these materials.

Flame Aerosol Synthesis and Electrochemical Characterization of Ni-Rich Layered Cathode Materials for Li-Ion Batteries

“…Even for materials prepared at conditions 2 and 3, where the as-prepared NCM811 particles had a defined (if irregular) micron-scale single-particle morphology, annealing causes this structure to collapse. A similar overall morphological change for long annealing times (10–20 h) of Li-rich Li 1.28 Mn 0.54 ­Ni 0.13 Co 0.13 O 2 powders prepared using spray pyrolysis has also been noted . For the layered NCM811 synthesized here, we confirmed that annealing for a shorter duration (4 h) or reducing the Li content in the precursor solution does not noticeably affect the observed changes.…”

“…Using such a process, examples of cathode materials that have been produced are spinel LiMn 2 O 4 and LiNi 0.5 Mn 1.5 O 4 , Li-rich materials, − LiCoPO 4 -C composites, and layered LiNi 0.33 Co 0.33 ­Mn 0.33 O 2 (hereafter referred to as NCM111), ,− using precursor solutions which are atomized into droplets on the 1–10 μm scale and delivered to self-supporting flames or tube furnaces. Several observations can be made.…”

Flame aerosol synthesis of nanostructured materials and functional devices: Processing, modeling, and diagnostics

“…In our eyes, these applications should cut across many fields, beyond just energy- developments in measurement, modeling, and integration with process control will further enable the development of flame aerosol reactor systems to produce the nanomaterials and devices that will impact society. [49] Lithium acetylacetonate 250 toluene [52] lithium nitrate 253 methanol [50] water [46]; [48];…”

“…xylene:tetrahydrofuran=1:1 [140] Cobalt naphthenate mineral spirits/xylene [351]; [361] Cobalt(II) nitrate(+4H2O,+6H2O) 100 1-propanol [148] 55 +6H2O) Ethanol [141]; [148] Methanol [148] methanol:propionic acid=1:1; ethanol:propionic acid=1:1; 1-propanol:propionic acid=1:1; propionic acid/1-octanol; propionic acid/1-pentanol [148] Water [46]; [48] Cobalt [154] Water [46] Nickel(II) propionate water/propionic acid [153] Nickel [109]; [162]- [164] xylene:acetonitrile=1:1 [367] Copper Ethanol [161] Isopropanol [168] Water [49]; [157] water/citric acid(as the chelating agent) [166] Copper propionate water/propionic acid [44]; [45] Zinc naphthenate Ethanol [106]; [169]; [170] Toluene [52]; [468] toluene:acetonitrile=4:1 [171] toluene:acetonitrile=8:1 [466] [467] Toluene:methanol=7:3 [172] Methanol:acetic acid=1:1 [80] mineral spirits/xylene [427] Zinc water/acetic acid [133] water/nitric acid [179] Strontium chloride 874 water/nitric acid [179] Strontium nitrate 570 Dimethylformamide [108] dimethylformamide:ethanol=4:1 [108] Water…”

“…(C1-C3) carboxylic acids [63] alcohol, carboxylic acid, or a mixture [76]; [77] ethanol [123]; [364] linear alcohols (C1-C8) [63] Vanadyl naphthenate naphthenic acid/toluene:2-ethylhexanoic acid=1:1 [ [359] Water [81] water/acetic-acid (some N 2 H 4 to prevent Mn 2+ oxidation) [133] Manganese(II) acetylacetonate 248-250 acetic acid (some N 2 H 4 to prevent Mn 2+ oxidation) [133] methanol/acetic acid mixture [130] Toluene [468] Manganese [134] Isopropanol [129] Methanol [50] propionic acid [135] Water [46] Manganese [138] mineral spirits/xylene, pyridine, or a mixture [85] Iron(III) acetylacetonate 180-182 ethanol [137]; [144] Methanol [373] methanol/acetic acid mixture [130] Toluene [136] xylene/acetonitrile=63/22 [79] Toluene [136] Iron(III) naphtenate mineral spirits/o-xylene:acetonitrile=3:1 [102] mineral spirits/xylene [51] mineral spirits/Xylene:acetonitrile=11:5 [104] Xylene [105] Iron(III) nitrate(+9H 2 O) 47(+9H 2 O) 2-ethylhexanoic acid:tetrahydrofuran:ethanol=2:2:1 [138] Ethanol [141]; [501] Water [142]; [469] Water/N,N-dimethylformamide=1:3 [358] Iron pentacarbonyl -20 -- [143] Co [147];…”