Fabrication of all solid-state rechargeable lithium battery and its electrochemical properties

An all solid-state rechargeable lithium battery was successfully fabricated using a ceramic electrolyte and a thin film technique. A polymer-modified sol–gel method was applied in order to prepare the electrode-coated ceramic electrolyte. Li4Ti5O12 known for its outstanding electrochemical performances and the partially crystallized glass ceramics, LiTi2(PO4)3–AlPO4 were adopted as electrode and electrolyte materials, respectively. The all solid-state battery cell constructed with lithium metal, PMMA buffer, and electrode-coated ceramic electrolyte was electrochemically evaluated with ac impedance, cyclic voltammetry, and discharge–charge test. The impedance of the interface between Li4Ti5O12 film and the solid electrolyte showed a relatively low resistance of~ 110 Ω cm−2 at 1.60 V. Highly reversible sharp redox peaks were observed at around 1.55 V from cyclic voltammograms, and these were still clear even at a high scan rate of 3 mV s−1, indicating a fast electrochemical response. A charge–discharge experiment showed an excellent reversibility of the cell but a relatively smaller discharge capacity of 100.49 mAh g−1 at C/5 than theoretical one of 175 mAh g−1. This may be due to formation of an interlayer at the interface, which may be caused by chemical reaction between Li4Ti5O12 and the ceramic electrolyte during a firing step during preparation. In spite of the undesirable side-reaction, the ceramic electrolyte was successfully applied to the solid-state rechargeable lithium battery by means of a thin film technique using the polymer-modified sol–gel method, through increasing the interfacial contact area, i.e. reducing the interfacial resistance.