A facile solid-state chelation meth

A facile solid-state chelation method using citric acid as the solid chelant was investigated for the synthesisof layered LiNi1/3Co1/3Mn1/3O2 as a cathode material for rechargeable lithium-ion batteries. The reactionwas promoted by high-energy ball milling. During the synthesis, PVP was used as an additive. Forcomparison, LiNi1/3Co1/3Mn1/3O2 was also synthesized by a conventional sol–gel method using citric acidas the chelant. The as-prepared samples were characterized by TG-DSC, XRD, FESEM, BET specificsurface area and galvanostatic charge–discharge tests. Based on the XPS, TEM and ED results, thesample synthesized by the solid-state chelation method with the PVP as an additive and subsequentcalcination at 900
C for 12 h in air was well indexed to a pure-phase hexagonal a-NaFeO2 structurewith the highest crystallinity. The resulting sample showed an initial discharge capacity of 173 mA h g1in the potential range of 2.6–4.5 V and at a rate of 0.1 C, higher than that of the sample prepared by thesame method without the use of a PVP additive during the synthesis (146 mA h g1). Moreover, theelectrochemical results at different current rates and the cycle performance for 100 cycles at 0.5 Cindicated that the sample prepared by the solid-state chelation method exhibited better rate capabilityand cyclic stability than that prepared by the conventional sol–gel method. This phenomenon promisessolid-state chelation as a new universal method for the preparation of functional materials.