High performance screen printable lithium-ion battery cathode ink based on C-LiFePO4

摘要

Lithium-ion battery cathodes have been fabricated by screen-printing through the development of C-LiFePO4 inks. It is shown that shear thinning polymer solutions in N-methyl-2-pyrrolidone (NMP) with Newtonian viscosity above 0.4 Pa s are the best binders for formulating a cathode paste with satisfactory film forming properties. The paste shows an elasticity of the order of 500 Pa and, after shear yielding, shows an apparent viscosity of the order of 3 Pa s for shear rates corresponding to those used during screen-printing. The screen-printed cathode produced with a thickness of 26 mu m shows a homogeneous distribution of the active material, conductive additive and polymer binder. The total resistance and diffusion coefficient of the cathode are similar to 450 Omega and 2.5 x 10 (1) 26 cm(2) s (1), respectively. The developed cathodes show an initial discharge capacity of 48.2 mAh g (1) at 5C and a discharge value of 39.8 mAh g (1) after 50 cycles. The capacity retention of 83% represents 23% of the theoretical value (charge and/or discharge process in twenty minutes), demonstrating the good performance of the battery. Thus, the developed C-LiFePO4 based inks allow to fabricate screen-printed cathodes suitable for printed lithium-ion batteries. (C) 2016 Elsevier Ltd. All rights reserved.