A cathode composite of La2(Ni/Co)O4, La0.9Ba0.1F2.9 and Super P was prepared by ball-milling 30 wt. % La2(Ni/Co)O4, 60 wt. % solid electrolyte and 10 wt. % Super P for 2 hours at 250 rpm in a 50 ml ZrO2 jar with 10 pieces of 10 mm zirconia balls in argon atmosphere. A composite of La0.9Ba0.1F2.9 and Super P was prepared by ball-milling 90 wt. % solid electrolyte with 10 wt. % Super P with the same parameters and ball-milling equipment.