PAMLiB: New materials for Li-Ion batteries with reduced cost and improved safety

• Forschungsstelle: EU FRP
• Projektnummer: 00.0033
• Projekttitel Englisch: PAMLiB: New materials for Li-Ion batteries with reduced cost and improved safety

Schlüsselwörter (Englisch)

Graphite; carbons; negative electrode material; secondary lithium batteries

Alternative Projektnummern (Englisch)

EU project number: ENK6-1999-00013

Forschungsprogramme (Englisch)

EU-programme: 5. Frame Research Programme - 1.4b.2 Economic and efficient energy for a competitive Europe

Kurzbeschreibung (Englisch)

See abstract

Partner und Internationale Organisationen (Englisch)

Coordinator: Saft SA, Romainville (F)

Abstract (Englisch)

The task objective for TIMCAL Group in the PAMLiB-project is the development of a new carbon negative electrode material as an alternative to the commonly used meso carbons like meso carbon micro beads (MCMB) or meso carbon fibers (MCF) with significantly lower material costs, an improved abuse tolerance at the cell level and an improved energy and power density of the cell. Another driving force for the development of an alternative to the meso carbons in the lithium-ion battery negative electrode is the fact that meso carbons cannot be produced in Europe due to the environmental regulations.In second year the project work was focused on the optimisation of graphite negative electrode materials with a specially rounded particle shape as well as on the optimisation of the graphite porosity of highly crystalline graphite materials.1. Graphite materials with rounded particle shapeIn the first year of the project it was found that graphites with a specially rounded particle shape show not only an electrochemistry which fulfil the requirements for the project but also show an improved processability and a better adhesion on the current collector of the negative electrode. In this report period a process scale-up was successfully performed to produce this new graphite family in the scale of some hundreds of tons. 3x100 kg of the most promising material were produced. These large scale samples have already been applied in industrial proto-type batteries for feasibility tests at SAFT. Long-term tests are still running. Initial tests show the same or even improved results compared to the reference electrode. These materials also fulfil the cost requirements of 10 Euro/kilogram given by the specifications of the project. To reach the final cost targets of 5 Euro/kg efforts were undertaken to further decrease the manufacturing costs of such materials. The process economy was improved and more efficient process steps were applied to produce such type of materials. Samples obtained from these trials have been under investigation in test batteries at present.2. Optimisation of the porosity of graphite negative electrode materialsThe graphite porosity is the main contributor to the relatively high BET surface area of high crystalline graphite compared to MCMB leading to high irreversible capacities when such materials are applied in negative electrodes of lithium-ion batteries. To improve this porosity, different carbon precursors were tested as raw materials for graphitisation. Besides new graphite materials with lower BET surface area also very promising materials have been found which reveal improved lithium plating properties at low temperatures. Both material types have been further evaluated in battery tests at SAFT. A second strategy to decrease the porosity was to apply different surface treatments on already graphitised samples. Promising new treatments were developed to significantly decrease the specific BET surface area. It was found that a significantly decreased BET surface area does not lead necessarily to an improved irreversible capacity in the first charge/discharge of the negative electrode. To obtain graphite negative electrode materials which show an improved irreversible capacity, it is not only important to control the treatment parameters but also to adjust the raw materials which are used for the treatment. On the same time it also seemed to be important to adjust cell parameters like binder and electrolyte to achieve the optimum results for these treated graphite negative electrode materials in the battery.In addition during these trials some evidence has been found that the rhombohedral stacking defects which can be observed in the graphite structure have no direct influence on the irreversible capacity as well as the tendency of the graphite electrode material to exfoliate during the electrochemical insertion of lithium. It could be shown that this graphite exfoliation is a surface-driven process. These new results were submitted for publication to the Journal of Electrochemical Society.

Datenbankreferenzen (Englisch)

Swiss Database: Euro-DB of the
State Secretariat for Education and Research
Hallwylstrasse 4
CH-3003 Berne, Switzerland
Tel. [phone]
Swiss Project-Number: 00.0033