Lead-based systems as suitable anode materials for Li-ion batteries

Three lead-based materials formed by PbO2, PbO and Pb as main phases were prepared by following different synthetic procedures and tested as anodic materials in Li-ion batteries by using potentiostatic and galvanostatic methods. While the reduction of Pb(IV) to Pb(II) takes place in a single step, that of Pb(H) to Ph is a complex process involving several steps. Both reduction reactions are irreversible. Lead, whether electrochemically or chemically formed, undergoes an electrochemical reaction with lithium that over the 1.0-0.0 V potential range yields LixPb alloys (0 less than or equal to x less than or equal to 4.4). The anodic and cathodic potentiostatic curves exhibit various signals that account for: (i) the formation of different intermediates with variable lithium contents; (ii) the reversibility of the alloying/de-alloying processes; (iii) the increase in complexity of such processes as the oxidation state of lead in them decreases. This results in capacity fading with cycling, particularly in the samples having Pb as the main component. One way of avoiding the capacity loss on cycling involves depositing the active material on lead sheets from spraying suspensions. These coatings exhibit a good capacity retention, which can be ascribed to the formation of a LixPb layer at the active material/substrate interface that facilitates electron and ion transfer across the electrode. (C) 2002 Elsevier Science Ltd. All rights reserved.