Flame‐assisted spray pyrolysis of lithium and manganese precursors to polycrystalline LiMn₂O₄

Abstract

Lithium manganese oxide cathodes have a smaller environmental footprint compared to cathodes with cobalt and nickel. Flame assisted spray pyrolysis (FASP) is an emerging technique that may improve the economics of the process at the commercial scale while controlling purity. LiNO 3 reacts with Mn(NO 3 ) 2 to form LiMn 2 O 4 . Carbon from the flame coats the particles and, together with the Mn oxides, they reduce electrical capacity. The reaction temperature and droplet residence time are the main parameters that determine manganese oxide content and therefore the product purity. LECO carbon analysis confirms that the fuel and precursor type affect carbon content. It increases from 0.1 % with nitrate precursors to 2 % with carbonate and acetate precursors. The temperature profile as well as the solute type and concentration change the product morphology. The particle surface is wrinkled at a mild temperature and blowholes form at a high temperature. Primary nano-crystals (5-8 nm) agglomerate to form 1 m polycrystalline particles from a 0.5 mol · L −1 nitrate precursors solution, while a 5 mol · L −1 solution produces 10 m powders. We modelled the reaction kinetics based on thermogravimetric analyses to identify the principle reaction steps. Oxide formation increases below 400 • C and above 800 • C, while fast heating rates and short residence time reduce purity.

Preferential Growth of the Cobalt (200) Facet in Co@N–C for Enhanced Performance in a Fenton-like Reaction

“…The calcination of melamine will form g-C 3 N 4 at 823 K, and slow weight loss can be observed before 823 K . Areas I, II, and III correspond to the stages when LiNO 3 , NaNO 3 , and KNO 3 are decomposed to produce gas, respectively. , It can be seen that the initial decomposition temperature increases gradually following the increase in their molecular weight, and the temperature of complete decomposition will also gradually increase. The left nitrates could be completely decomposed in the constant temperature stage at 1123 K. The hysteresis loops of the samples are then tested and shown in Figure d.…”

Experimental methods in chemical engineering: Thermogravimetric analysis—TGA

“…[12][13][14] The peaks of the DTG correspond to inflection points, while for the case of overlapping peaks, the DDTG (onset temperatures) separate reactions more precisely. [15] The temperature at which two extrapolated lines intersect is the onset temperature.…”

“…The first and second derivatives of the weight loss profile (DTG and DDTG) identify inflection points and discriminate phenomena of multicomponent mixtures that react at overlapping temperatures (Figure ) . The peaks of the DTG correspond to inflection points, while for the case of overlapping peaks, the DDTG (onset temperatures) separate reactions more precisely . The temperature at which two extrapolated lines intersect is the onset temperature.…”

Morphological changes of vanadyl pyrophosphate due to thermal excursions

“…The resolution is 0.1 µg and the accuracy is 0.1 %. The maximum load for the apparatus is around 0.1 g but loading more than 20 mg causes a decrease in the rate of mass transfer due to the sample shielding in the pan [76] .…”

“…The maximum load for the TGA Q500 is around 0.1 g, but loading more than 20 mg, decreases the mass transfer rate due to the shielding of sample on the pan. [76] . We measured volume and density of the samples by an AccuPyc 1340 Folio Instrument with three different chamber volumes (1, 3.5 and 10 mL) (Table 5.2).…”