A lithium secondary battery configured to have a structure in which an electrode laminate is mounted in a case in a sealed state, wherein the electrode laminate comprises: positive electrodes, each having a positive electrode material coating layer formed on a positive electrode current collector; negative electrodes (111, 112), each having a negative electrode material coating layer formed on a negative electrode current collector; and porous polymer films (121, 122), each interposed between a positive electrode and a negative electrode (111 or 112), wherein the positive electrodes, the negative electrodes (111, 112), and the porous polymer films (121, 122) are laminated in a height direction on the basis of a plane such that two negative electrodes constitute outermost electrodes of the electrode laminate, the positive electrode material coating layer has a larger coating area than the negative electrode material coating layer, a total capacity of the negative electrodes is less than that of the positive electrodes (N/P ratio < 1), the electrode laminate further comprises a combination of a first radical cell (302 or 304), a second radical cell (301, 303 or 305), and a separation sheet interposed between the first radical cell (302 or 304) and the second radical cell (301, 303 or 305) covering the sides of the first radical cell (302 or 304) and the second radical cell (301, 303 or 305), the first radical cell (302 or 304) has a structure in which one of said negative electrodes (111 or 112) is interposed between two of said positive electrodes, and two porous polymer films (121, 122) are interposed respectively between the positive electrodes and the negative electrode (111 or 112), the second radical cell (301, 303 or 305) has a structure in which one of said positive electrodes is interposed between two of said negative electrodes (111, 112), and two porous polymer films (121, 122) are interposed respectively between the positive electrode and the negative electrodes (111, 112), the separation sheet covers the sides of the first radical cell (302 or 304) and the second radical cell (301, 303 or 305) at which no electrode terminals are formed, the negative electrode material coating layer comprises a lithium metal oxide represented by Li 1.33 Ti 1.67 O 4 or LiTi 2 O 4, and the positive electrode material coating layer comprises a spinel-structure lithium metal oxide represented by Formula 2 below: Li x Ni y Mn 2-y O 4 wherein 0.9 ≤ x ≤ 1.2 and 0.4 ≤ y ≤ 0.5. positive electrodes, each having a positive electrode material coating layer formed on a positive electrode current collector; negative electrodes (111, 112), each having a negative electrode material coating layer formed on a negative electrode current collector; and porous polymer films (121, 122), each interposed between a positive electrode and a negative electrode (111 or 112), wherein the positive electrodes, the negative electrodes (111, 112), and the porous polymer films (121, 122) are laminated in a height direction on the basis of a plane such that two negative electrodes constitute outermost electrodes of the electrode laminate, the positive electrode material coating layer has a larger coating area than the negative electrode material coating layer, a total capacity of the negative electrodes is less than that of the positive electrodes (N/P ratio < 1), the electrode laminate further comprises a combination of a first radical cell (302 or 304), a second radical cell (301, 303 or 305), and a separation sheet interposed between the first radical cell (302 or 304) and the second radical cell (301, 303 or 305) covering the sides of the first radical cell (302 or 304) and the second radical cell (301, 303 or 305), the first radical cell (302 or 304) has a structure in which one of said negative electrodes (111 or 112) is interposed between two of said positive electrodes, and two porous polymer films (121, 122) are interposed respectively between the positive electrodes and the negative electrode (111 or 112), the second radical cell (301, 303 or 305) has a structure in which one of said positive electrodes is interposed between two of said negative electrodes (111, 112), and two porous polymer films (121, 122) are interposed respectively between the positive electrode and the negative electrodes (111, 112), the separation sheet covers the sides of the first radical cell (302 or 304) and the second radical cell (301, 303 or 305) at which no electrode terminals are formed, the negative electrode material coating layer comprises a lithium metal oxide represented by Li 1.33 Ti 1.67 O 4 or LiTi 2 O 4, and the positive electrode material coating layer comprises a spinel-structure lithium metal oxide represented by Formula 2 below: Li x Ni y Mn 2-y O 4 wherein 0.9 ≤ x ≤ 1.2 and 0.4 ≤ y ≤ 0.5.