The Studying Of The Influence Of Dispersant To The Properties Of Carbon Coating LiFePo₄ Anode Material

Since the concept of polyanion was proposed by Goodenough, Li Fe PO4 was be considered as one of the most promising anode material especially in the application of the electric vehicle(EV). Because of the merits that environmental friendliness, economy and stable discharging flat.However, the demerits of Li Fe PO4, low tap density, poor electronic conductivity and low ionic diffusivity limit the application of Li Fe PO4.In this paper,we utilized liquid polyacrylonitrile(LPAN) to modify Li Fe PO4 in order to overcome the shortcomings of it. We studied the influencing factor to the electrochemical performance in 5 aspects as follows: the content of LPAN, the polarity of dispersant, the p H value of dispersant and the additive in dispersant. We characterized the electrochemical performance of Li Fe PO4 via constant charging and discharging test, and characterized the structure and morphology of Li Fe PO4 by RAMAN, XRD, SEM and TEM.1.The paper discussed the influence of precursor’s preparation method to the Li Fe PO4,in this paper the precursor was prepared via sand grinding-spray drying method and high performance ball mill method. The results showed that: a spindle-like hierarchical structure was obtained via sand grinding method while the irregular particles was obtained via high performance ball mill method.2.The paper discussed the influence of LPAN content to Li Fe PO4,in this paper a series of Li Fe PO4 was obtained, and the LPAN content of it is 4%, 6%, 8%, 10wt%, respectively. The results illustrated that: the Li Fe PO4 with 6wt% LPAN shows the best specific capacity,the specific capacity in 0.1c was 130 m Ah/g.3.The paper discussed the influence of the dispersant’s polarity to Li Fe PO4,in this paper, a series of Li Fe PO4 was obtained in a series of dispersant with different polarity. The results illustrated that: The lower dispersant’s polarity result in the smaller particles size of the Li Fe PO4.And Li Fe PO4 prepared in the lowest polar dispersant,decyl alcohol, have the smallest particle and it also show the best specific capacity, the specific capacity in 0.1c was 170 m Ah/g.4.The paper discussed the influence of the dispersant’s p H to Li Fe PO4,in this paper a series of Li Fe PO4 was obtained in different p H dispersant. The results illustrated that: Li Fe PO4 prepared in the lowest p H value have the smallest particle, and Li Fe PO4 prepared in the p H value of 3 shows the best specific capacity, it reached 170 m Ah/g in 0.1c.Furthermore, all the Li Fe PO4 prepared in the alkaline condition showed the poor specific capacity, it resulted from the oxidation of Fe2+ during the preparation process.5.The paper discussed the influence of the additive in dispersant to Li Fe PO4,in this paper,the cetyl trimethyl ammonium bromide(CTAB)served as the additive. The results showed that, the Li Fe PO4 containing 4wt% CTAB had the highest capacity, which reached 129 m Ah/g in 1c.