Elsevier

Electrochimica Acta

Volume 150, 20 December 2014, Pages 129-135
Electrochimica Acta

Poly vinyl acetate used as a binder for the fabrication of a LiFePO4-based composite cathode for lithium-ion batteries

https://doi.org/10.1016/j.electacta.2014.10.123Get rights and content

ABSTRACT

This paper describes a method for the preparation of composite cathodes for lithium ion-batteries by using poly vinyl acetate (PVAc) as a binder. PVAc is a non-fluorinated water dispersible polymer commonly used in a large number of industrial applications. The main advantages for using of this polymer are related to its low cost and negligible toxicity. Furthermore, since the PVAc is water processable, its use allows to replace the organic solvent, employed to dissolve the fluorinated polymer normally used as a binder in lithium battery technology, with water. In such a way it is possible to decrease the hazardousness of the preparation process as well as the production costs of the electrodes. In the paper the preparation, characterization and electrochemical performance of a LiFePO4 electrode based on PVAc as the binder is described. Furthermore, to assess the effect of the PVAc binder on the electrode properties, its performance is compared to that of a conventional electrode employing PVdF-HFP as a binder.

Section snippets

INTRODUCTION

The electrodes used in lithium-ion battery technology are formed by an electro-active material, carbon and a polymer binder which primarily ensures the mechanical stability of the electrodes. The characteristics of the binding material are of vital importance for a correct functioning of the battery. The traditional polymer for producing electrodes for Li-ion batteries is the poly(vinylidene fluoride-co-exafluoropropylene) (PVdF-HFP). The production process (solvent-based) for the electrode

Preparation of the PVAc-based cathode

The preparation described herein refers to a 100 cm2 of cathode tape. Lithium iron phosphate (Gelon lib Group, ShanDong, P.R. China) and carbon black (Super P, MMM, Belgium) were used as the active material and the conductive agent, respectively. 1.5 g of lithium iron phosphate and 0.25 g of carbon black were weighed and transferred to a mechanic mill (Mixer Mill MM200, Retsch) and mixed by operating the device for a few minutes. PVAc with a solid mass fraction of 50% was used (Vinavil SpA via

Chemical-physical characterization

It has been reported that the electrode thickness notably influences the charge/discharge rate capability, energy density, power density, and long-term cycling behavior of LiFePO4 based cathodes [14]. Electrode thickness also has a significant impact on the energy density of the electrode since thicker electrodes can reduce the fraction of inactive materials such as current collectors and separators [15]. The morphology of the as deposited electrode was investigated by scanning electron

CONCLUSION

In this work, for the first time, the use of PVAc as a binder in the formulation of a LiFePO4 based-electrode for lithium-ion batteries is described. A suspension of the active material, carbon and PVAc was used to paint a thin aluminum sheet. The so obtained electrode possesses an appropriate porosity to allow the electrolyte to penetrate in its inside. The electrode has shown interesting electrochemical properties making it suitable for the realization of high-energy/high power lithium-ion

ACKNOWLEDGMENTS

Part of this work was carried out within the activities “Ricerca Sistema Elettrico” funded through contributions to research and development by the Italian Ministry of Economic Development.

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