later this result indicated that lithium sulfide and carbon were bonded to each other to achieve a higher density moreover using the composite obtained in this manner as a positive electrode active material of a lithium ion secondary battery the charge discharge test was conducted in the same manner as in example 1 the charge discharge performance is as shown in fig5 a that is the initial charge capacity was about 350 mah g and the initial discharge capacity was about 130 mah g these were remarkably higher than those measured in comparative example 2 described later in which a starting material mixture before electric current sintering was used as a positive electrode active material fig5 b initial charge capacity 0 6 mah g and initial discharge capacity 27 mah g the above results demonstrated that the utilization of lithium sulfide was greatly raised by combining lithium sulfide and carbon by electric current sintering under the conditions employed in the present invention as with example 2 0 2 g of lithium sulfide li 2 s average particle diameter 16 u03bcm and 0 2 g of acetylene black ab specific surface area 68 m 2 g lithium sulfide acetylene black weight ratio 1 1 were weighed in a glove box in an argon gas atmosphere they.