1. A Lead Monoxide Precursor of High Surface-Area for Lead-Acid Battery Paste R Vasant Kumar Department of Materials Science University of Cambridge, UK

2. Acknowledgements Seref Sonmez, Vega Kotzeva, Jiakuan Yang, Lilia Sanchez, Richard Darby, Yingjun Liu, David Zou, of Department of Materials Science Lei Wang, Nigel Williams of the Business School Maggie Wilkinson & Zlatka Stoeva of Cambridge Enterprise

3. A Schematic Cut-Away of Lead Battery

4. Table 1Range of Compositions from a dry lead battery paste MaterialWt % Lead sulphate55-65 Lead dioxide15-40 Lead monoxide5-25 Metallic lead1-5 Carbon black, plastics, fibres, other sulphates 1-4

5. Current Method - Pyrometallurgy *For 10,000 tpy plant Capital: $4- 5M Energy: 14,000MWH *Independent Consultants

6. Battery Manufacture Lead is then chemically oxidised to PbO for the battery industry PbO is electrochemically reduced to Pb and oxidised to PbO 2 to make anode and cathode

7. Lead containing Organic Crystalline Compounds PbO Precursor New A new process for recycling lead battery waste → ↓ ↑ → Special Leaching/Crystallization Process Lead Battery Combustion/ Calcination Process Manufacturing Lead Battery Waste Battery Paste New Paste Patent: PCT/GB2007/ 004222; WO2008/056125 RV Kumar, S Sonmez and V Kotzeva

8. A new process for recycling lead battery waste → Paste Pb Grid Heat Energy from paste recycling New Grid New Paste directly from paste recycling Kettle Waste Battery New lead Battery

9. Green PB Recycling Process Patent: PCT/GB2007/ 004222; WO2008/056125 RV Kumar, S Sonmez, V Kotzeva Used Paste Crystalline Compoun ds PBO Precur sor New Past e New Battery Wast e Batt ery Leaching Combustion- Calcination Spent Lead grid Metallic Lead Energy

10. Leaching of battery paste PbO and PbO 2 Ratio of Paste/ reagent

12. pH vs time for varying paste/reagent ratio

13. XRD Pattern of A: Standard Lead citrate; B: from PbO; C: from PbO 2 and D: from PbSO 4

14. Lead organic crystallites of Lead citrate (A) from PbO and PbO 2

15. SEM images of Lead Citrate (B) from PbSO 4

16. Precursors Ideal weight loss From dehydrating weight loss (TGA) Ideal weight loss For decompo sition to PbO weight loss after exother mic peak of TGA weight loss calcined at 350 ℃ for 1h Precursor I [Pb(C 6 H 6 O 7 )]·H 2 O 4.3%4.20%46.3%49.8%48.2% Precursor II [Pb(C 6 H 6 O 7 )]·H 2 O 4.3%4.20%46.3%49.8%49.0% Precursor III [Pb 3 (C 6 H 6 O 7 ) 2 ]·3H 2 O 5.1%5.50%36.6%38.3%37.5% Combustion-Calcination of Lead citrates in Air

17. Wt loss and heat produced on decomposing Pb citrate (A)

18. Wt loss and heat produced from lead citrate (B)

19. Mixture of α and β PbO and metallic Pb – can be controlled to varying ratios

20. Heat Produced Combustion-calcination of lead citrates can generate thermal energy of 2 kJ/ g of lead battery paste The Raceway Adiabatic Flame Temperature is over 1500K! This energy is equivalent to 550 kWh/kg of paste!

21. PbO morphology after combustion-calcination SEM TEM

22. Spongy PbO Agglomerated PbO Skeletal PbO

23. Additives during leaching to control PbO morphology Lead citrate PbO

24. Addition of C-fibre to PbO precursor

25. FEGSEM – Each fibre is coated with PbO

26. Physical Properties of PbO Free Pb: 0 to 20 % Crystal structure: α/β ratio: 0.05 to 1 Crystal size: 20 – 100 nm Particle average size: 1 – 5 μm Specific surface area (BET) m 2 /g: 2.4 to 5.5 Acid absorption (mg H 2 SO 4 / g oxide): 270 – 530

27. Preliminary Electrochemical Testing First discharge capacity in the 130 – 160 mAh/g of PbO Increase in discharge capacity with no of cycles up to 8-10 cycles and then remained constant to 50 cycles Further work is ongoing A B C D E A: PbO /PbSO 4 reduction to Pb B: Pb oxidation to PbSO 4 C: PbSO 4 oxidation to PbO 2 D: PbO 2 reduction to PbSO 4 E: PbSO 4 reduction to Pb

28. The Green PB Process For 10,000 tpy plant Capital: $1-1.5 M Energy: 1750 MWH 5000 MWh Energy available

29. Conclusions New method for directly recovering PbO from spent battery paste Many control variables available to vary physical properties of PbO product Promising preliminary results Thank You