Fabrication of high power LiNi0.5Mn1.5O4 battery cathodes by nanostructuring of electrode materials

Abstract

Using nanoparticles, instead of microparticles, as active electrode materials in lithium ion batteries could provide a solution to slow charging rates due to long ion diffusion pathways in conventional bulk materials. In this work, we present a new strategy for the synthesis of high purity lithium nickel manganese oxide (LiNi_0.5Mn_1.5O₄) nanoparticles as a high-voltage cathode. A sonochemical reaction is used to synthesize nickel hydroxide and manganese dioxide nanoparticles followed by a solid-state reaction with lithium hydroxide. The product shows a single spinel phase and uniform spherical nano-particles under the appropriate calcination conditions. The LiNi_0.5Mn_1.5O₄ exhibits a high voltage plateau at about 4.7–4.9 V in the charge/discharge process and delivers a discharge capacity of more than 140 mA h g⁻¹ and excellent cycling performance with 99% capacity retention after 70 cycles. The synthesized nano-particles show improved electrochemical performance at high rates. This electrode delivers a power density as high as 26.1 kW kg⁻¹ at a discharge rate of 40 C. This power performance is about one order of magnitude higher than traditional lithium ion batteries. These findings may lead to a new generation of high power lithium ion batteries that can be recharged in minutes instead of hours.