Effect of surface fluorination and conductive additives on the electrochemical behavior of lithium titanate (Li4/3Ti5/3O4) for lithium ion battery

Effect of Conductive Additives and Surface Fluorination on the Electrochemical Properties of Lithium Titanate (Li[sub 4/3]Ti[sub 5/3]O[sub 4])

“…The BET surface area of original Li 4/3 Ti 5/3 O 4 was 7.3 m 2 /g, which was much larger than 2.8 m 2 /g of Li 4/3 Ti 5/3 O 4 ͑Ϸ4.6 m͒ used in a previous study. 32 Surface areas were 7.4, 7.4, and 6.0 m 2 /g for the samples fluorinated by F 2 at 70, 100, and 150°C, respectively. When NF 3 was used for fluorination, surface areas were slightly increased ͑7.5, 8.2, and 8.1 m 2 /g for the samples fluorinated at 100, 150, and 200°C, respectively͒.…”

“…The charge/discharge data for Li 4/3 Ti 5/3 O 4 ͑Ϸ0.8 m͒ used in the present study were better than those obtained for Li 4/3 Ti 5/3 O 4 ͑Ϸ4.6 m͒ used in a previous paper. 32 First charge capacities obtained at 60 mA/g in 1 mol/L LiClO 4 -EC/DEC were 158 and 143 mAh/g for AB and VGCF additives, respectively, being similar to those obtained for Li 4/3 Ti 5/3 O 4 ͑Ϸ4.6 m͒ in a previous study ͑147 and 150 mAh/g for AB and VGCF, respectively͒. 32 32 The reproducibility of the first charge/discharge capacities and first coulombic efficiency on each run of experiment was high within Ϯ2 mAh/g and less than 1%, respectively.…”

“…The effect of the mixing ratio among Li 4/3 Ti 5/3 O 4 , conductive additive, and PVdF was examined in a previous paper. 32 Charge capacities slightly increased with increasing conductive additive for both AB and VGCF ͑Li 4/3 Ti 5/3 O 4 :AB:PVdF = 6:1:2, 6:2:2, 6:3:2 and Li 4/3 Ti 5/3 O 4 :VGCF:PVdF = 6:0.5:2, 6:1:2, 6:2:2͒. The increments in the charge capacities with an increase in the conductive additives were 6-15 and 4-8 mAh/g for AB and VGCF, respectively.…”

“…1. 32 However, it was also revealed that thin carbon fibers were twined with each other in the VGCF, which interferes with the uniform mixing of VGCF with Li 4/3 Ti 5/3 O 4 particles. In the present study, we have used fine Li 4/3 Ti 5/3 O 4 powders with an average particle size of 0.8 m to improve electrode characteristics and mixtures of VGCF and AB to obtain better electric contact between Li 4/3 Ti 5/3 O 4 particles and a nickel current collector.…”

Surface fluorinated LiNi0.8Co0.15Al0.05O2 as a positive electrode material for lithium ion batteries

“…Hence, a new surface modification method with a simple dry process for positive electrode materials has been recently reported: surface fluorination. [28][29][30][31] Here, to our knowledge, we reported for the first time a modification on NCA positive electrode material by a one-step, facile and dry surface fluorination method. It is known that the electronegativity of F is the strongest among all the elements, leading to the strongest electrophilic ability.…”