Overview
POMEROL addressed the technology of lithium-ion batteries for hybrid vehicles, primarily for fuel-cell hybrid vehicles (FCHEV).
Several years of intensive worldwide R&D efforts have been dedicated to solving the problems of lithium metal cycling efficiency in rechargeable lithium batteries. In the early 1990s, metallic lithium was replaced by a carbon anode able to form intercalation compounds, so-called Li-ion. The potential use of this battery technology for the ICE-HEV (Internal Combustion Engine Hybrid Electric Vehicles) automotive applications and fuel cells under development is clearly a highly important issue and is responsible for a major part of the size, weight and cost challenges facing all organisations in the attempt to reach a true market position for these applications.
With an adequate choice of materials, a very long life cycle can be achieved. However, cost, abuse tolerance and power remain major issues for the technology development in hybrid drivetrains.
POMEROL intended to develop high power, low-cost and intrinsically safe lithium-ion batteries by a breakthrough in materials. The materials and batteries are dedicated to fuel-cell hybrid and conventional hybrid drivetrain automotive applications.
WP1: New positive materials
Main goals of this WP were:
- To develop low cost and high performance lithium iron phosphate and lithium transition metal fluorinated oxide positive electrode material based on Ni and Mn.
- To design adapted materials particle size, composition and morphology.
- To carry out physico-chemical and structural characterisations.
- To evaluate the electrochemical and safety behaviour.
- To select the best material for further up scaling.
WP2: Advanced graphite materials
Main goals of this WP were:
- To develop a new low cost graphite material according to project specifications.
- To develop a graphite with a controlled surface to reduce capacity consumption during cell formation.
- To identify key graphite material parameters which influence the cell performance in the high current drain.
- To prepare and characterise different carbon additives and to study and optimise their effect on the cell performance at high charge and discharge currents.
WP3: Ionic liquid-based electrolytes
Main goals of this WP were:
- To develop innovative ionic liquids compatible with Li-ion electrochemistry.
- To select additives to passivate the negative electrode.
- To identify and eliminate critical impurities of the ionic liquids and electrolytes with cost effective processes.
- To formulate electrolytes containing the ionic liquids and evaluate all their electrochemical properties.
- To validate performances at laboratory scale of cells including the ionic liquid based electrolytes.
WP4: Scale-up of materials and processes
Main goals of this WP were:
- To achieve and demonstrate the scale-up of the selected positive electrode material, negative electrode material and show the feasibility of an industrial manufacturing process.
- To achieve and demonstrate the scale-up of the selected ionic liquid based electrolyte.
- To achieve and demonstrate the scale-up of the electrode processes to obtain high power and low-cost electrodes.
- To provide electrodes for prototype and scale
POMEROL developed innovative solutions through the development of speciality materials (LiFePO4, lithiated metal fluorinated oxides, non-flammable ionic liquid-based electrolytes and high-performance graphitised carbons), which would respond to the very ambitious challenge of adequate low cost, safety and life.
POMEROL combined seven industrial partners and specialised subcontractors, all having proven expertise in the research, development and production of materials and batteries. Having automotive end-users, material suppliers and a battery maker in the Consortium allowed for a rapid validation of the results, saving time and resources.
Funding
Results
Main technical achievements are as follows:
- New positive materials
F-NMC and LiFePO4 have been considered as new positive active materials. F-NMC material work was stopped by decision at the MTA meeting and the project was subsequently focussed only on LiFePO4. Five different Fluorine-doped Ni-Co-Mn based materials were synthesised with different routes and many samples of LiFePO4 materials were synthesised from different routes (CEA and UMICORE) with different particles sizes, morphologies and compositions. Low-cost samples have also been delivered during year 3. - Advanced graphite materials
New graphite negative electrode materials have been synthesized, characterised and electrochemically tested in lab cells as well as in industrial batteries. The development activities have focused on the following research directions:- The particle size and shape of graphite materials based on synthetic and natural graphite have been improved in order to optimize the electrode packing and electrode porosity for an optimal high power capability of the cell.
- The graphite particle size distribution of the graphite electrode materials have been optimized to minimize the surface area and thus to allow sufficient storage at elevated temperatures, safety, and battery life.
- To evaluate the influence of the graphite crystallinity on the high current rate performance, new graphite materials with various degree of crystallinity were prepared from different carbon precursors and with different graphitization procedures.
- The influence of the graphite surface have been investigated by preparing graphite materials with specially designed surface morphologies.
Three promising graphite materials have passed the challenging high current pulse power and storage tests requirements and were selected for further investigations in pilot batteries. The up-scaling of these graphite materials has been evaluated and cost calculations for industrial quantities have been performed.
- Ionic liquid based electrolytes
During the project, Merck KGaA synthesised, purified to electrochemical grade, characterised and optimized a huge variety of electrochemical stable ionic liquids. The techniques used for characterisation include conductivity and viscosity measurement of single ionic liquid and complex electrolyte formulation, determination of the electrochemical stability using cyclic voltammetry at differentReadiness
The most significant deliverables at the end of the project were cells with good power and low cost.
Furthermore, safety was demonstrated at the level of cells and module (short circuit test).
The results obtained in this project led to a large number of publications in scientific journals and participation in several international meetings. Moreover, two patents were filed from the results of this project.