Post-doping via spray-drying: a novel sol–gel process for the batch synthesis of doped LiNi_0.5Mn_1.5O₄ spinel material

Powder granulation, Ti-doping and thermal post-treatment have beneficial effects on the electrochemical performance of 5 V LiNi_0.5Mn_1.5O₄ (LNMO) spinel materials. It is shown that spray-drying combined with a post-doping process step is suitable to prepare Ti-doped 5 V materials with a defined and highly reproducible microstructure and chemical composition. Powder granulation via spray-drying and thermal post-treatment provides spherical LNMO granules with nano-crystalline primary particles and a 10 % higher specific discharge capacity compared to pristine LNMO materials due to the presence of the partially ordered P4 ₃ 32 spinel phase and the reduced Mn³⁺ content. Powder granulation combined with a post-doping process step which utilizes titanium containing sol leads to spherical LiNi_0.5Mn_1.47Ti_0.03O₄ granules with uniform nano-crystalline primary particles and a homogenous Ti distribution. The second calcination process after spray-drying as well as the Ti-doping cause a reduced content of the Li _x Ni_1−x O impurity phase. This facile sol–gel processing leads to doped LiNi_0.5Mn_1.47Ti_0.03O₄ with an increased discharge capacity of 18 % compared to the original material. All the granulated materials show a good rate performance up to 10 C due to their particular microstructure.