Nanosize LiNiyMn2 - yO4 (0 < y ≤ 0.5) spinels synthesized by a sucrose-aided combustion method. Characterization and electrochemical performance

• Published in: Journal of materials chemistry 2004-01, Vol.14 (10), p.1640-1647
• Main Authors: LAZARRAGA, M. G, PASCUAL, L, GADJOV, H, KOVACHEVA, D, PETROV, K, AMARILLA, J. M, ROJAS, R. M, MARTIN-LUENGO, M. A, ROJO, J. M
• Format: Article
• Language: English
• Subjects: Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Materials science; Physics
• ISSN: 0959-9428; 1364-5501
• DOI: 10.1039/b314157h

Nanosize crystalline cathode materials of LiNiyMn2-yO4 (y up to 0.5) composition and spinel-type structure were obtained by a single-step sucrose-aided self-combustion method. The as-prepared samples contained some amorphous organic impurities that were removed after a short period of heating at 500 C. The pure single-phase spinels were characterised by XRD, TEM, chemical analysis, and nitrogen sorption isotherms. The samples consist of particles (about 24 nm size) that are aggregated in clusters (about 1 micron size) in which mesopores (10-80 nm size) appear among the particles. Additional heating at 800 and 1000 C produces a slight increase in the cubic lattice parameter and a pronounced increase in particle size ( > 100 nm). Electrical conductivity decreases as the Ni content increases in accordance with an electron hopping mechanism between Mn3+ and Mn4+ ions. The 500 C- and 800 C-heated LiNi0.5Mn1.5O4 samples show good electrochemical behaviour at 4.7 V as cathode materials. The capacity (132.7 mA.h/g) found is close to the nominal capacity (146.7 mA.h/g) and remains constant for current densities in the range C/24-2C (where C = 2.6 mA/cm2). At higher current densities (2C-10C) the capacity decreases progressively. The cyclability at the C current density is about 99.7% for both samples. 44 refs.