Lithium-ion batteries - Anodes

Lithium metal is the highest energy-density anode material for the lithium-battery. But it too unstable and hence a safety hazard. A major challenge is therefore to find a safer material in which to store and transport lithium ions in the battery. Carbonaceous materials like graphite are cheap and environmentally safe but low in energy density.

There are several metals (M) that alloy with lithium e.g. Al, Sb, and Sn. These binary LixM systems provide high energy density, but the large volume expansion upon lithiation (150 % for Sb) results in disintegration of the material and dramatically limit the cycle life.

Very high energy densities could be obtained with Si-anode. However, as for Li-metal alloys, the problems due to large volume expansion of LixSi system need to be addressed.

To understand the performance of these anode materials, both the mechanisms of the intercalation/alloying reactions and the details of the side-reactions (e.g. electrolyte decomposition, surface passivation, particle cracking) need to be studied. (See the schematic picture of reactions occurring at the graphite anode upon charging.)

Based on this knowledge, composition and morphology of the anode electrode can be optimized to to give maximum electrode capacity, safety and lifetime.

Research activities

• Different carbonaceous anode materials, their Li-ion intercalation capabilities in various electrolytes and optimization of their morphology for a battery electrode.
• Metals, metal alloys and intermetallic anodes with optimized morphologies for Li-storage.
• Silicon anodes - synthesis, characterisation and understanding of Li-ion intercalation process in different electrode morphologies.
• Understanding of the anode surface and anode-electrolyte interface-film (SEI)properties, the behaviour of the surface at high temperatures, anode corrosion.

Techniques

• XRD, XPS (in-house)
• In-situ XRD and XPS (at the synchrotron radiation facility at MAX-lab in Lund)
• Raman
• EQCM
• SEM
• TEM
• Electrochemical testing
  

Funding

Swedish Research Council (VR)