Preparation And Properties Of Modified Cathode Materials For Lithium-Ion Battery

In recent years, with the increasing attraction on electric vehicles, and manyresearchers and institutions start to study the lithium battery, especially the cathode.Although there are plenty of cathode materials, they have structural defects respectively. Inthis report, we summarized the research results which were published recently on cathodematerials for the lithium battery, and we modified two of the most attractive materials,which were lithium-rich manganese-based materials and Lithium iron phosphate. Thisarticle studied their structure, morphology, composition and electrochemical performance,and analyzed why they had excellent performance.The precursor for Li1.2Mn0.54Ni0.13Co0.13O2was synthesized by carbonateco-precipitation method. And ultrasound-assisted mixing lithium was used in mixingprecursor with LiOH, and then the mixture was calcined at high temperature to obtain theLi1.2Mn0.54Ni0.13Co0.13O2. The obtained compound was characterized by X-ray diffraction(XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) andX-ray photoelectron spectra (XPS), indicating that it had excellent layered structure andsuperior crystallinity. The electrochemical test showed that the first discharge capacity was298mAh g-1and the capacity retention was91.2%after100cycles. Meanwhile, thismaterial had outstanding rate performance. The highest discharge capacity of this materialwas190mAh g-1and almost no capacity fading after100cycles. To understand the reasonof high electrochemical performance of the D-LMNCO electrode, the electrode wasmeasured and examined by XRD and SEM after100cycles, and the result indicated thatthis unique structure could overcome stress-induced structural collapse which was causedby Li-ion insertion/extraction and reduced the dissolution of transition metal ions.Ultrasound-assisted mixing lithium was also used to synthesize Li1.2Mn0.6Ni0.2O2, theresults of SEM and TEM showed that the morphology was rod-like structure which wassimilar to the Li1.2Mn0.54Ni0.13Co0.13O2above, and those demonstrated thatUltrasound-assisted mixing lithium was able to affect the structure and morphology duringthe preparation. The highest discharge capacity was245mAh g-1and the capacity retentionwas87.8%after100cycles at0.1C. Meanwhile, the electrospinning method was adoptedto prepare the lithium-rich manganese-based material. And the XRD and SEM test showed that it did not have a good layered structure and crystallinity, therefore, the experimentscheme should be modified.Super P was utilized to coat the commercial LiFePO4and to improve itselectrochemical performance. The formation of two carbon layer web enhanced theelectronic and ionic conductivity. Due to this particular carbon web, the discharge capacitywas beyond the theoretical capacity at0.1C, which was193mAh g-1. The carbon web wasjust like a capacitor that could supply the extra capacity.