Effect of C and Au additives produced by simple coaters on the surface and the electrochemical properties of nanosized LiFePO4

We examined the use of two conductive additives (C and Au) to boost the performance of lithium iron phosphate as a positive electrode material for lithium ion batteries. The phosphate was prepared by using a new, fast synthetic method that provides nanosized particles. Carbon and gold were sputtered on LiFePO4. Additional sample was an intimate mixture of carbon and phosphate by mechanochemical-pyrolitical synthesis. Although the voltammetric tests revealed that the addition of these conductive materials expedited electron transfer kinetics, the effect on galvanostatic cycled cells was found to depend largely on the nature and way of introduction of the additive (carbon or metal). Surface analysis and electrochemical impedance spectroscopy on cycled electrodes provided a better understanding of the special behaviour of the carbon and gold composites obtained by sputtering. (C) 2009 Elsevier B.V. All rights reserved.