Nano-particulate electrode materials, electrode materials modified by surface layers in the nm- range (core-shell materials) and nano-structured composite electrodes and electrolytes offer tremendous opportunities to overcome the limitations of current lithium polymer microbatteries, e.g. reduces transport limitations within the materials and to decrease the over-potential required for intercalation/deintercalation reactions. Intelligent composite electrodes require a well-designed spatial distribution o f the various components. Simple mixing does not create optimised percolation patterns of conductive additives or other functional components. Self- assembling of nano-particles on preconditioned surfaces can be used to create optimised 3-dimensional mult i percolation patterns by use of the "binderless" Substrate Induced Coagulation (SIC).
Li4Ti5O12 shows excellent capacity retentions at various C rates and temperatures with a better safety than common electrode materials. This compound in the form of nano-tubes and nano-fibres is characterised by extremely fast Li+-intercalation /deintercalation. Adequate electronic contacts for high-rate operation of these electrode materials can be made by SIC-coating. Increased volumetric energy density on the anode side can be achieved by replacing carbon-based materials by lithium storage metals and alloys as silicon-lithium composite. These alloys have a very high capacity of 570 mAh/g 1 per lithium and per silicon, up to 4.4 lithium.
Lithium insertion/extraction on this material leads to an important volume variation, which causes a capacity fading upon cycling. To overcome this fading the active materials have to be in a nano state. A new separator generation can be designed with a nano organic-ceramic hybrid (O RMOCER). A polymer battery will be realized with these materials and techniques and can be mass- produced after the modification of existing processes and lines at Varta Microbattery.
Fields of science
- engineering and technologyenvironmental engineeringenergy and fuelsrenewable energysolar energy
- engineering and technologymaterials engineeringcomposites
- natural scienceschemical sciencesinorganic chemistryalkali metals
- natural scienceschemical sciencespolymer sciences
- engineering and technologynanotechnologynano-materials
- FP6-NMP - Nanotechnologies and nanosciences, knowledge-based multifunctional materials and new production processes and devices: thematic priority 3 under the 'Focusing and integrating community research' of the 'Integrating and strengthening the European Research Area' specific programme 2002-2006.
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