K.H. Prasad, R. Arumugam, E.S. Srinadhu, N. Satyanarayana
Keywords: RF magnetron sputtering, Li1.3Al0.3Ti1.7 (PO4)3 thin-film electrolytes, XRD, impedance, DC & AC conductivities, electrical modulus
Summary:During the past few decades, all solid state thin film lithium-ion batteries have drawn more attention due to their many possible applications, such as smart cards, CMOS, FE-RAM, micro-electric devices, liquid crystal displays (LCDs), etc., especially, more emphasis on micro-power sources in portable electronic devices. Also, the solvent-free all-solid-state rechargeable lithium-ion batteries are the most suitable, as par as safety is concerned, for their use in large-scale battery systems. For this, polymer [2-6] and ceramic [7-13] solid electrolytes have been developed and studied to eliminate the flammable components in the rechargeable Li-ion battery. Particularly, all-solid-state batteries with ceramics solid electrolyte is recognized as an ultimate safe battery. In the present work, set of thin film lithium aluminum titanium phosphate [Li1.3Al0.3Ti1.7 (PO4)3 (LATP)] electrolytes were grown on Ti/Si (100) substrates at ambient temperature by RF magnetron sputtering. All the prepared thin films were annealed at 200 oC, 300 oC, 400 oC, and 500 oC under an oxygen atmosphere to enhance the crystallinity. All the as prepared as well as the annealed thin films were characterized using XRD and also studied their DC & AC conductivities and electric modulus properties by analyzing the measured impedance data using win fit software. Fig. 1 shows the Log (σT) vs. 1000/T plots obtained at room temperature of LATP thin films as-deposited and post-annealed at different temperatures. From fig.1, the Log (σT) vs. 1000/T plots showed the plato at low frequency region and dispersion at high frequency region. Fig. 2. shows the typical imaginary part of electric modulus (M'') versus frequency plots obtained at room temperature of LATP thin films as deposited and post-annealed at different temperatures. From fig. 2, M'' versus Log (ω) plots showed the peak and it shifts towards higher frequency with increase of frequency. The evaluated conductivity results indicated that the LATP electrolyte thin film deposited in argon atmosphere and post-annealed at 500 oC showed the high ionic conductivity of 5.37×10−5 S cm−1. The observed high ionic conductivity (5.37×10−5 S cm−1) of the LATP electrolyte thin film post-annealed at 500 oC may be useful as solid electrolyte for developing all-solid-state thin film lithium-ion batteries. Detailed results will be presented and discussed.