Environmental Friendly Electrode Preparation for Hybrid Battery-Supercapacitors Based on Li₃V_1.95Ni_0.05(PO₄)₃/C and Activated Carbon

Abstract

In the last years, hybrid battery-supercapacitors have been a rising interest toward the improvement of both the energy density and power density in comparison to the classical systems [1]. By using Li-insertion materials and activated carbon it is possible to develop high energy and high power density Li-ion supercapacitors. Among the various numbers of Li-ion materials, Li3V1.95Ni0.05(PO4)3/C shows excellent performances at very high C-rates, with very high specific discharge capacity (93 mA h g-1 at 100 C) and a capacity retention of 97% after 1000 cycles [2]. Most of the currently used Li-ion battery electrodes are based on poly(vinylidene difluoride) (PVDF) due to its good electrochemical stability and binding capability within the electrode composite. However, the cost and the environmental impacts of these widely used PVDF based electrodes are still a concern in the battery industry. Thus, lot of effort has been put toward the pursuit of an environment-friendly, cost-effective binder for lithium-ion batteries, such as carboxymethyl cellulose (CMC) and polyacrylic acid (PAA) [3].In this study, the effect of CMC and PAA binders in the battery-like counter part on the mechanical and electrochemical behaviour in the hybrid battery-supercapacitor electrodes is explored (see Table 1). In particular, Li3V1.95Ni0.05(PO4)3/C has been studied both as high energy and high power anode and cathode, between 3.0-1.5 and 3.0-4.3 V vs. Li+/Li. Commercial activated carbon (AC) (Haycard) and LP30 (Merck) has been used as counter electrode and electrolyte, respectively. Furthermore, the functionalization of PAA during the electrode preparation will be investigated and shown during the presentation. Table 1. Electrode compositions. Compositions Active material LVNP / wt.% Conductive agent Super P / wt.% Binder /wt.% 1 80 10 9% CMC + 1% SBR 2 85 5 9% CMC + 1% SBR 3 86 5 9% PAA References [1] D. Cericola, R. Kötz, Electrochim. Acta 72 (2012) 1–17. [2] M. Secchiaroli, G. Giuli, B. Fuchs, R. Marassi, M. Wohlfahrt-Mehrens, S. Dsoke, DOI: 10.1039/c5ta00976f. [3] J. Chong, S. Xun, H. Zheng, X. Song, G. Liu, P. Ridgway, J. Q. Wang, V. S. Battaglia, J. Power Sources 196 (2011) 7707– 7714. Acknowledgments Financial support from the German Federal Ministry of Education and Research (BMBF) under the grant 03EK3021 is gratefully acknowledged.