A lithium ion polymer secondary cell, wherein a porous material which comprises a fluoropolymer having vinylidene fluoride as its primary polymer unit and has a density of 0.55 to 1.30 g/cm<3> and a Gurley value of 150 sec/100 cc or less is used as a base material of a being arranged between a positive electrode and a negative electrode. Such a solid electrolyte exhibits improved ion conductivity, and thus provide a lithium ion polymer secondary cell being improved in low temperature characteristics, cycle characteristics and high rate discharge characteristics, as compared to a conventional one.
