Executive Summary : | For the past one decade, development of all-solid batteries for the energy applications is a hot topic among the research groups working in the field of Li and Na ion batteries. However, realizing all-solid-state thin film batteries for the practical applications is been a great challenge and have not yet been strike into commercial success. Engineering the electrode materials such as cathode, solid electrolyte and anode for all-solid-state systems has succeeded thus far-producing several candidates. However, manufacturing and commercial production techniques are still in the very early stage. Interface conductivity between the cathode/electrolyte and electrolyte/anode is a key factor in deciding the maximum accessible current of a thin film Li ion battery. In addition to the interface conductivity, diffusivity of the Li ion and the electrons in the components play an important role. Since the thin film surface can be very well controlled and altered by growth parameters and the buffer layers, it can be made very flat and conducting interface area between the cathode/anode and solid electrolyte can be tuned to the apparent contact area. In addition to that, volume of the cathode and anode layer and their quality decides the overall capacity of the thin film all-solid battery. By controlling the interface conductivity, one can achieve the high capacity of a thin film battery with more than 80% of the cathode consumption. Main aim of the present proposal is to employ in-situ three target sputtering system to grow all the three electrode components without breaking the vacuum to avoid the interface related issues and also by employing few buffer layers (i.e. LiNbO₃ and graphite) at the interface to get flat interface with less resistance between cathode/electrolyte and electrolyte/anode. This proposal is to utilize several strategies to improve the interface related drawbacks and fabricate an all-solid-state lithium ion thin film battery using a low cost RF sputtering fabrication method and then test the cell using standard electrochemical testing methods. High voltage and capacity cathodes (LiMn3/2Ni1/2O4, LiMn2O4, LiCo1/3Mn1/3Ni1/3O2), highly stable anode (Li4Ti5O12) and high ionic conducting solid electrolytes (Li3xLa2/3−xTiO3 and Li7La3Zr2O12) with excellent stability against Li metal will be employed to fabricate the thin film batteries. Thin layers of LiNbO3 and graphite buffer layers will be deposited at the interfaces to improve the conductivity. Final goal is to fabricate high energy density all-solid thin film batteries with lighter weight and wider electrochemical window (5 to 5.5 V) in small and large size for energy applications with the energy density of 300 to 400 Wh/kg. |