Nanostructured LiNi_(0.5)Mn_(1.5)O_4 cathode material synthesized by polymer-assisted co-precipitation method with improved rate capability

摘要

The polymer-assisted oxalate co-precipitation method has been developed to synthesize nanostructured LiNi_(0.5)Mn_(1.5)O_4. In this method, polyacrylic acid (PAA) as a dispersant agent was applied in the co-precipitation process to achieve the well-dispersed and homogenous precursor route. The obtained powder possesses small particle around 50-100 nm as compared to the one synthesized by traditional co-precipitation method. Besides, the porous texture was also found in as-fabricated LiNi_(0.5)Mn_(1.5)O_4. The X-ray diffraction reveals the well-crystallized cubic spinel structure without the presence of undesired impurities, such as NiO or Li_xNi_(1-x)O, commonly found in other fabrication method. An excellent cycling stability is obtained with the capacity retention over 90% after 100 cycles in 1 C at room temperature. Moreover, the superior rate capability was also derived by nanostructured LiNi_(0.5)Mn_(1.5)O_4, in which the discharge capacity in 5 and 7 C is around 110 and 100mAhg~(-1), respectively. The greatly enhanced rate capability is attributed to the significantly shortened Li-ion diffusion pathway, associating with the nano-textured particle morphology.