Effect Of Flexible Conductive Carbon Nanotube Cellulose Paper On The Electrochemical Performance Of LiNi_1/3Co_1/3Mn_1/3O₂ Ternary Cathode Materials

LiNi_1/3Co_1/3Mn_1/3O₂ Ternary cathode material has high specific capacity and energy density and is part of the most popular positive electrode active material on the market today. Aluminum foil is a traditional cathode current-collector for lithium ion batteries. Aluminum foil also was used as the current-collector of Ternary cathode material. The current-collector plays the function of collecting and exporting current, which plays a very important role for the performance of the battery. However, the density of the aluminum foil is large and there is no other additional function. So,the research of the current-collector has a positive significance. Carbon nanotube is a kind of low-density nano carbon material with excellent strength and toughness. After graphitization treatment, the degree of crystallinity and purity of the carbon nanotubes were significantly improved. Flexible Conductive Carbon Nanotube Cellulose Paper?conductive paper? was prepared by composite carbon nanotube with the paper fiber as the basic framework. The conductive papers have not only excellent electrical conductivity, but also has excellent flexibility. In addition, flexible conductive carbon nanotube cellulose paper contains a lot of micro-pore and shows good compatibility with cahtode material. At the same time, it can absorb and store more electrolyte and improve interface structure and reduce interface resistance. The internal chemical reaction is greatly improved with the conductive papers. This paper investigate the electrochemial properties of lithium ion battery with conductive paper and aluminium foils as cathode current collector respectively.This paper has also research the process of graphitization of carbon nanotube, the preparation of flexible Conductive Carbon Nanotube Cellulose Paper, determination of carbon nanotubes content, performance comparison of carbon nanotubes and traditional conductive agents?SP? etc. The results identify as following:1.Graphitization of carbon nanotubes can improve the crystallinity, the degree of graphitization, purity of carbon nanotubes. The purity of CNTs reached more than 99%. Meanwhile, the graphitization reduce greatly the defects of carbon nanotube. It also improves the stability of the structure of CNTs.2. Flexible Conductive Carbon Nanotube cellulose paper has good conductivity and good interface binding performance, rich micro-pores and good absorbency of electrolyte. Its surface resistance is 5.6 /Sq.3.Ternary cathode materials were doped by CNT with a 0.5wt%, 1wt%, 2wt%, 5wt%, 10wt% and 20wt%. The capacity of a lithium ion battery reached 138 m Ah/g with 5wt% CNTs at 0.1C charge-discharge rate under 3.0⁴.2V voltage sections. The cycle performance of the battery was enhanced greatly.4.The battery capacity reach 178 m Ah/g with 5wt%CNT and 162 m Ah/g with 5wt% SP respectively under 2.0⁴.5V voltage segments and 0.1C charge-discharge rate. The rate performance of CNT also showed better than SP. Three types of positive electrodes were prepared. a) ternary Material /5%CNTs/ conductive paper current-collector, b) Ternary Material /5%CNTs/ aluminum foil current-collector, c) Ternary Material /5%SP/ aluminum foil current-collector. The testing results identify the first discharge specific capacity reached184 m Ah/g, 178 m Ah/g and 162 m Ah/g at 0.1C charge-discharge rate for an electrode of a, b, c respectively.The electrode of ternary Material /5%CNTs/ conductive paper current-collector showed the maximum capacity and the capacity retention rate is above 97% after 28 cycles. Capacity is retaining rates declined at high discharge rate. The further works need to be done.