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Master thesis or semester project on thin-film solid-state batteries
Investigate thin films deposited by magnetron sputtering as electrolyte for all-solid-state lithium-ion batteries. Study the effect of processing parameters and addition of dopants in the ionic and electronic conductivities and test the electrolyte in a thin film battery architecture.
The trend to more and more powerful mobile devices as well as the surge of electric vehicles are pushing the necessity of safe energy storage solutions with higher energy densities. However, the standard Li-ion batteries with liquid electrolyte will soon reach a limit for energy density. A promising workaround consists in replacing the liquid electrolyte by a solid-state electrolyte. This technology has the potential to offer higher energy densities and extended lifetime as well as reduce safety issues and enable new geometries and form factors.
In the last years the research community has worked extensively in the development of superionic conducting materials, such as the crystalline lithium garnet Li7La3Zr2O12 (LLZO), which offers ionic conductivities close to the standard liquid electrolytes and possesses a wide electrochemical stability window. However, this material has to be crystallized at high temperatures and suffers from lithium dendrite formation issues.
The trend to more and more powerful mobile devices as well as the surge of electric vehicles are pushing the necessity of safe energy storage solutions with higher energy densities. However, the standard Li-ion batteries with liquid electrolyte will soon reach a limit for energy density. A promising workaround consists in replacing the liquid electrolyte by a solid-state electrolyte. This technology has the potential to offer higher energy densities and extended lifetime as well as reduce safety issues and enable new geometries and form factors. In the last years the research community has worked extensively in the development of superionic conducting materials, such as the crystalline lithium garnet Li7La3Zr2O12 (LLZO), which offers ionic conductivities close to the standard liquid electrolytes and possesses a wide electrochemical stability window. However, this material has to be crystallized at high temperatures and suffers from lithium dendrite formation issues.
In this project the student/intern will investigate an alternative approach consisting in the deposition of thin films (below 500 nm) of the amorphous phase of LLZO.
The main scientific challenge of this concept will be the enhancement of the conductance of Li ions in the amorphous electrolyte. Magnetron sputtering will be employed for the deposition of the electrolyte thin films. The deposition process parameters will be optimized to achieve conformal films with superior ionic conductivities. The incorporation of dopants like aluminum or gallium will be investigated.
Prepared layers will be investigated with different characterization methods including scanning electron microscopy (SEM) and time-of-flight Secondary ion mass spectrometry (ToF-SIMS). Ionic conductivity will be measured using impedance spectroscopy of the films. The performance of the prepared electrolytes will be tested in a thin-film battery architecture consisting of LiCoO2 as a cathode and lithium metal as an anode. The thin-film batteries will be characterized employing electrochemical characterization methods like cyclovoltammetry and charge-discharge.
In this project the student/intern will investigate an alternative approach consisting in the deposition of thin films (below 500 nm) of the amorphous phase of LLZO.
The main scientific challenge of this concept will be the enhancement of the conductance of Li ions in the amorphous electrolyte. Magnetron sputtering will be employed for the deposition of the electrolyte thin films. The deposition process parameters will be optimized to achieve conformal films with superior ionic conductivities. The incorporation of dopants like aluminum or gallium will be investigated. Prepared layers will be investigated with different characterization methods including scanning electron microscopy (SEM) and time-of-flight Secondary ion mass spectrometry (ToF-SIMS). Ionic conductivity will be measured using impedance spectroscopy of the films. The performance of the prepared electrolytes will be tested in a thin-film battery architecture consisting of LiCoO2 as a cathode and lithium metal as an anode. The thin-film batteries will be characterized employing electrochemical characterization methods like cyclovoltammetry and charge-discharge.
Jordi Sastre (jordi.sastrepellicer@empa.ch), Dr. Yaroslav Romanyuk (yaroslav.romanyuk@empa.ch)
Jordi Sastre (jordi.sastrepellicer@empa.ch), Dr. Yaroslav Romanyuk (yaroslav.romanyuk@empa.ch)