Lithium polyacrylate-coated LiMn2O4 cathode materials with excellent performance for lithium ion batteries

摘要

A novel facile approach to coat LiMn2O4 by lithium polyacrylate (PAALi) is demonstrated. The PAALi-coated LiMn2O4 (LMO@2%PAALi) and LiMn2O4 (LMO) are characterized by charge-discharge tests, X-ray diffraction (XRD), PAALi dissolving experiment, transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetry (TG), and inductively coupled plasma optical emission spectrometer (ICP-OES). XRD and FTIR analyses indicate that there are no clear differences between LMO@2%PAALi and LMO. PAALi dissolving experiment indicates that PAALi is indissolvable in LiPF6-EC/DMC/EMC electrolyte. TEM results reveal that LiMn2O4 particles are coated by PAALi. ICP-OES results indicate that this stable PAALi coating can prevent the Mn ions dissolving from active LiMn2O4 materials and then the stability of LiMn2O4 crystals in electrolyte are greatly enhanced. These unique features ensure that LMO@2%PAALi possesses much better rate performance, higher discharge capacity, better cycling performance, and lower charge transfer resistance over LMO. The discharge capacity of LMO@2%PAALi at 0.2 C reaches up to 127.2 mAh g(-1) at room temperature.