A
solid electrolyte includes: LiaAbEc(SO4)dJeXfHh, A is selected from alkaline earth metals and alkali metals other than Li, E is selected from Al, Ga, In, Sc, Y, Ti, Zr, Hf, and lanthanides, J is selected from OH, BO2, BO3, BO4, B3O6, B4O7, CO3, NO3, AlO2, SiO3, SiO4, Si2O7, Si3O9, Si4O11, Si6O18, PO3, PO4, P2O7, P3O10, SO3, SO5, S2O3, S2O4, S2O5, S2O6, S2O7, S2O8, BF4, PF6, BOB, (COO)2, N, AlCl4, CF3SO3, CH3COO, CF3COO, OOC—(CH2)2—COO, OOC—CH2—COO, OOC—CH(OH)—CH(OH)—COO, OOC—CH(OH)—CH2—COO, C6H5SO3, OOC—CH═CH—COO, OOC—CH═CH—COO, C(OH)(CH2COOH)2COO, AsO4, BiO4, CrO4, MnO4, PtF6, PtCl6, PtBr6, PtI6, SbO4, SeO4, TeO4, HCOO, and O, X is selected from F, Cl, Br, and I, 0.5≤a<6, 0≤b<6,0<c<2,0.1<d≤6.0, 0<e≤6.0, 0<f≤6.1, and 0≤h≤0.2, and a peak is observed at a
diffraction angle 2θ=22.3°±1.0° in an X-
ray diffraction pattern in which Cu-Kα is used as a
line source.