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

Abstract

Lithium-ion battery cathodes have been fabricated by screen-printing through the development of CLiFePO4 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 mm shows a homogeneous distribution of the active material, conductive additive and polymer binder. The total resistance and diffusion coefficient of the cathode are 450 V and 2.5 10 16cm2 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 batteriesThis work was supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of the PTDC/CTMENE/5387/2014 and UID/CTM/50025/2013 projects and grants SFRH/BD/98219/2013 (J.O.), SFRH/BD/90313/2012 (A.G.), and SFRH/BPD/112547/2015 (C.M.C.). The authors thank financial support from the Basque Government Industry Department under R.E. Sousa et al. / Electrochimica Acta 196 (2016) 92–100 99 the ELKARTEK Program. SLM thanks the Diputación de Bizkaia for financial support under the Bizkaia Talent program. The authors thank Solvay, Timcal and Phostech for kindly supplying the high quality materials. LH acknowledges FEDER funds through the COMPETE 2020 Programme and National Funds through FCT - Portuguese Foundation for Science and Technology under the project UID/CTM/50025/2013”