Spinel-embedded and Li_3PO_4 modified Li[Li_(0.2)Mn_(0.54)Ni_(0.13)Co_(0.13)]O_2 cathode materials for High-Performance Li-Ion battries

摘要

Layered Li-rich and Mn-based oxides have been considered as competitive candidates for Li-ion batteries because of their high capacity (exceed 250 mAh g(-1)), environmentally benign, and low cost. However, their commercialization is restricted by their inherent drawbacks such as low initial coulombic efficiency, modest cycling performance and poor rate capability. To overcome these problems, we have proposed an construction strategy of a spinel-embedded and Li3PO4 modified Li[Li0.2Mn0.54Ni0.13Co0.12]O-2 oxides through a facile wet chemical deposition route. During the modification process, Li(+)in the pristine could be partially exchanged by H+ concomitant with the chemical deposition of Li3PO4. After a low-temperature calcination process, the spinel structure is formed accompanied with the extraction of H+ and the interaction between Li3PO4 coating layer and the surface of pristine particles was enhanced. The as-designed structure is characterized by Raman spectra, Energy-dispersive X-ray Spectroscopy (EDS), Transmission Electron Microscopy (TEM), and Cyclic Voltammetry (CV). The practical results confirm that the capacity retentions and rate capability are significantly improved after such modification. The modified sample delivers much higher capacity retention of 83.57% after 150 cycles at 1C rate compared with 70.44% for bare material. Our facile modification approach combines the advantage of spinel phase and Li-ion conductor Li3PO4 particles. It is very effective for the structural construction of robust electrolyte deteriorating durability as well as fast ion diffusion and storage capability in layered Li-rich and Mn-based oxides.