Effects of microstructure on fracture strength and conductivity of sintered NMC333

Abstract

Sintering of LiNi0.33Mn0.33Co0.33O2 cathode material was investigated for potential application in all‐electric aerospace propulsion systems utilizing new architectural concepts. All‐solid‐state batteries, while inherently safe, may not reach the high energy density required for next generation propulsion systems. To meet this performance requirement, multifunctionality of sintered active material may achieve systems level weight savings through simultaneous load bearing and electrochemical energy storage performance. The effects of sintering conditions on structural stability, chemistry, densification, grain size, fracture strength and electrical conductivity were quantified for the active cathode material. X‐ray diffraction and inductively coupled plasma results indicated the structure and stoichiometry were maintained across the range of processing conditions to facilitate intercalation. Densification was achieved by sintering at 1050°C in ambient atmosphere, but grain coarsening was observed for higher temperatures and longer hold times. Mechanical strength was improved with reduction in porosity, but excessive grain growth decreased strength, providing a maximum of 50 MPa for samples sintered at 1050°C for 10 hours. Electrical conductivity initially improved with densification, but significantly diminished as the microstructure coarsened. The optimal sintering condition of 1050°C maximized mechanical fracture strength and electrical conductivity, with shorter sintering times preferred.

Asynchronous-to-Synchronous Transition of Li Reactions in Solid-Solution Cathodes

“…Figure b shows literature reports ,− of the electrical conductivity of NMC materials (symbols) and the curve adopted in our computational model (continuous black line). The conductivity is several orders of magnitude lower in the pristine state than in the partially charged (delithiated) state. ,− This behavior is similar to LiCoO 2 and attributed to the transition from a semiconductor-like behavior to a metallic character caused by the initial Li removal. , Because of the capacity loss after the first cycle, the NMC particles will remain at a significantly higher electrical conductivity (in addition to higher diffusivity) for the start of the second charge (Figure b,c). Hence, we hypothesize that the low electrical conductivity of pristine NMC could explain the first charge asynchronous reactions.…”

Ultrathin 2D-oxides: A perspective on fabrication, structure, defect, transport, electron, and phonon properties

“…For example, Lithium cobalt oxide (LiCoO 2 , LCO) and its relative, lithium nickel manganese cobalt oxide (LiNi 1/3 Mn 1/3 Co 1/3 O 2 , NMC), are both layered transition metal oxides (TMOs) utilized primarily as the active cathode for the Li-ion battery industry. [93,94] NMC can also be exfoliated to form two-dimensional This is the author's peer reviewed, accepted manuscript. However, the online version of record will be different from this version once it has been copyedited and typeset.…”

Electronic and ionic properties of sintered cathode of LiNi0.6Mn0.2Co0.2O2 (NCM622)

“…Comparable data of 6. NCM333 with 64% density in a comparable measurement setup are reported by Huddleston et al 21 Therein, the sintering was performed at T = 1000 • C without any sintering additive, and no electrochemical measurement was done.…”

“…An intermediate step toward a full ceramic cathode could be the sintered cathode made of the cathode material itself without additional solid electrolyte but very low content of liquid Li‐ion conductor. The sinterability of NCM333 at high temperatures (1000–1100°C) is possible without detectable Li loss, 20 and the resulting microstructures are indicating high electronic conductivity of ∼6 × 10 −4 S cm −1 by the material itself 21 . Although impedance measurements are given for such a sintered cathode, the electrochemical performance in a cell was not shown.…”

“…The sinterability of NCM333 at high temperatures (1000-1100 • C) is possible without detectable Li loss, 20 and the resulting microstructures are indicating high electronic conductivity of ∼6 × 10 −4 S cm −1 by the material itself. 21 Although impedance measurements are given for such a sintered cathode, the electrochemical performance in a cell was not shown. Presumably, the thickness and density of the samples were too high, so that no Li conductive pathway by internal resistances was formed.…”