Electroless Copper-Based Coating on Lithium Iron Phosphate for Improved Performances

With Lithium-ion battery production increasing every year, a lot of efforts are involved in research and development of new advanced materials¹ capable of addressing the challenges that arise from the most interesting applications , such as hybrid electric vehicles (HEVs). In this work, the electroless metallization technique has been used to obtain a coating on the surface of active material particles used in the preparation of cathodes and anodes for Li-ion batteries.

One of the most promising candidates in the field of energy storage is the olivine-type LiFePO₄ (LFP). This particular material, which was first proposed by Padhi et al.², is characterized by high energy density, low cost and chemical stability. However, this material is presenting a major drawback in its low electronic conductivity due to its intrinsic resistance, and several routes are being investigated to mitigate this issue. Most common approaches are applying a Carbon coating on the surface of LFP^3–5, reduce particle size⁶ and particles doping⁷.

In this work, copper-based coating has been applied on LFP particles in order to enhance its electronic conductivity and eventually to increase the resistance to Fe dissolution during cycling, which is recognized as one of the main causes of capacity fading during cycling^8–10. The coating has been obtained with autocatalytic deposition, with a two-step process: (1) Pd-based particles activation and (2) copper plating through deposition bath containing copper ions and a reducing agent that allows the reduction of metal ions from the solution to the surface of the particles. Positive electrodes have been prepared using PVDF latex as polymeric binder. The resulting cathodes show improved electrical conductivity. Electrochemical characterization has been carried out to assess the nature of the coating and its impact on the performances of the electrode in working conditions.

Acknowledgments:

This work has been financed with the contribution of the LIFE financial instrument of the European Community. Project n° LIFE12 ENV IT 000712 LIFE+ GLEE.

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