In-Situ Heating X-Ray Diffraction of LiNi_0.6Mn_0.3Co_0.1O₂ and LiNi_0.7Mn_0.3O₂ Made Using the All-Dry Synthesis Process.

Area of Science:

• Materials Science
• Inorganic Chemistry
• Solid-State Chemistry

Background:

• Understanding the synthesis of layered transition metal oxides is crucial for advanced battery materials.
• The all-dry synthesis method offers advantages in terms of precursor handling and reaction control.

Purpose of the Study:

• To investigate the phase evolution during the all-dry synthesis of LiNi0.6Mn0.3Co0.1O2 (NMC631) and LiNi0.7Mn0.3O2 (NM73).
• To compare the effect of different lithium sources (LiOH·H2O vs. Li2CO3) on the synthesis pathway and final phase formation.

Main Methods:

• In-situ X-ray diffraction (XRD) at the Canadian Light Source.
• Heating samples to 950 °C under flowing oxygen.
• Analysis of cation incorporation and ordering during phase transitions.

Main Results:

• A common synthesis pathway involving lithiated manganese oxide, rock salt, and spinel phases was observed for all materials.
• The layered hexagonal structure formed through cation ordering above 800 °C.
• NMC631 synthesized using LiOH·H2O exhibited the earliest layered phase formation at approximately 820 °C.

Conclusions:

• The melting of LiOH appears to facilitate cation diffusion, promoting earlier layered phase formation compared to Li2CO3.
• The choice of lithium source significantly impacts the kinetics of layered oxide synthesis.
• Optimizing synthesis conditions, including the lithium source, is key to controlling the formation of high-performance battery materials.