Thermodynamic analysis of Li-Ni-Co-Mn-H2O system and synthesis of LiNi0.5Co0.2Mn0.3O2 composite oxide via aqueous process

• Published in: Journal of Central South University Vol. 26; no. 10; pp. 2668 - 2680
• Main Authors: Li, Yun-jiao, Li, Ling, Su, Qian-ye, Lu, Wei-sheng, Han, Qiang, Li, Lin, Chen, Yong-xiang, Deng, Shi-yi, Lei, Tong-xing
• Format: Journal Article
• Language: English
• Published: Changsha Central South University 01.10.2019; Springer Nature B.V
• Subjects: Aqueous solutions; Cathodes; Electrode materials; Engineering; Lithium compounds; Manganese; Metallic Materials; Morphology; Nickel; Precursors; aqueous process; Mn; 溶液过程; 正极材料; thermodynamics; cathode materials; 热力学; LiNi; Co; potential-pH diagrams; 电位−pH 图; O
• ISSN: 2095-2899; 2227-5223
• DOI: 10.1007/s11771-019-4204-6

The constructed potential-pH diagrams of Li-Ni (Co, Mn)-H 2 O system indicate that the LiNiO 2 , LiCoO 2 and LiMnO 2 are thermodynamically stable in aqueous solution within the temperature range of 25-200 °C and the activity range of 0.01-1.00. A predominant co-region of LiNiO 2 , LiCoO 2 and LiMnO 2 oxides (Li-Ni-Co-Mncomposite oxide) is found in the Li-Ni-Co-Mn-H 2 O potential-pH diagrams, in which the co-precipitation region expands towards lower pH with rising temperature, indicating the enhanced possibility of synthesizing Li-Ni-Co-Mn composite oxide in aqueous solution. The experimental results prove that it is feasible to prepare the LiNi 0.5 Co 0.2 Mn 0.3 O 2 cathode materials (NCM523) by an aqueous routine. The as-prepared lithiated precursor and NCM523 both inherit the spherical morphology of the hydroxide precursor and the obtained NCM523 has a hexagonal α-NaFeO 2 structure with good crystallinity. It is reasonable to conclude that the aqueous routine for preparing Ncm cathode materials is a promising method with the guidance of the reliable potential-pH diagrams to some extent.