Materials research for Li-ion batteries


Overview of different battery designs, indicating the importance of Li-ion batteries. 

Energy storage is more and more becoming an important challenge in our modern day society. Switching to renewable energy sources necessitates the need for high capacity off-grid energy storage, our day-to-day dependence on mobile technology demands light batteries with long cycle lives, and advances in microelectronics (whether or not for biomedical applications) require safe and dependable microbatteries. Lithium-ion batteries (LIBs) form the spearhead of this technology because it is at the high end of the power-/energy-density trade-off, making it the rechargeable battery of choice for future applications.

Schematic overview of the working principle of a LIB

Schematic overview of the working principle of a LIB

In rechargeable batteries, charge is carried by electrons on the one hand, and mobile ionic species (in this case lithium ions) on the other. Upon use (discharging), lithium ions migrate from the anode to the cathode. This charge transfer is compensated by the migration of electrons through the external load, thus delivering electrical energy.

Atomic layer deposition is an emerging technology in the field of LIBs and has proven to be beneficial in several fields, ranging from protective coatings for conventional powder-based electrodes, to deposition of electrode or electrolyte layers for 3D all-solid-state thin film batteries: 

Conventional powder-based electrodes-For these types of batteries, ultra-thin ALD coatings have proven to improve kinetics (batteries with higher power), as well as shield the electrode powders in lithium ion batteries from the electrolyte and decomposition products (HF, SEI formation). These coatings could help pave the way towards higher capacity anode materials on the one hand, and safer, cheaper, high potential cathode materials on the other.

3D all-solid-state thin film batteries -The need for bulk-material (powder-based) batteries can be circumvented by depositing thin electrode/electrolyte layers on complex 3D structures, raising the capacity per surface area by the internal surface factor of this structure. ALD can deliver great aspect-ratio coverage, yielding large capacity increases. An additional effect to these structures is that the slow bulk-diffusion kinetics in solid electrolytes are minimized in this approach, in effect making the batteries much faster to charge/discharge.

 Processes for anode/cathode/solid electrolyte materials are being developed using the existing ALD setups, and electrochemical and electrical characterization can be done in-house, in an Ar-filled glovebox (O2<1ppm, H2O<1ppm), connected to several commercial and home-built potentiostat/galvanostat devices.

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