In　this　work,　alkali-earth　metal　elements　(Mg,　Ca,　Sr,　Ba)　doped　Li13.9Sr0.1Zn(GeO4+delta)(4)　electrolyte　is　prepared　by　sol-gel　method.　The　influence　of　alkali-earth　metal　doping　on　the　phase　structure,　morphology,　Li+/H+　ion　exchange　and　electrical　conduction　behavior　of　Li13.9Sr0.1Zn(GeO4+delta)(4)(LSZG)　electrolyte　is　characterized　by　X-ray　diffraction,　scanning　electron　microscopy,thermal　gravimetric　analyzer　and　electrochemical　impedance　spectroscopy.　The　powders　of　Mg,　Ba　and　Sr　doped　Li13.9Sr0.1Zn(GeO4+delta)(4)　electrolyte　are　found　to　possess　the　same　phase　structure　as　LSZG　powders.　The　grain　size　and　density　of　Mg,　Ba　and　Sr　doped　LSZG　samples　increase　significantly　after　sintering　at　1050　degrees　C.　Ca　is　partially　doped　into　the　LSZG　lattice,　and　some　is　precipitated　in　the　form　of　CaGeO3　second　phase.　The　doping　elements　can　promote　the　ion　exchange　of　Li+/H+　in　LSZG　electrolyte.　With　the　increase　of　ion　radius　of　doping　elements,　the　Li+/H+　ion　exchange　rate　of　samples　gradually　decreases.　The　proton　conductivity　of　all　doped　samples　is　significantly　higher　than　that　of　pure　LSZG　electrolyte　pellets.　Mg　is　considered　to　be　the　best　doping　element.　In　5%　H-2-Ar　humid　atmosphere,　the　proton　conductivity　of　Li13.8Mg0.1Sr0.1Zn(GeO4+delta)(4)(LMSZG)　electrolyte　at　0.9　V　bias　voltage　is　about　0.053　S/cm　at　600　degrees　C.　The　proton　conductivity　of　LMSZG　sample　with　BaZr0.4Ce0.4Y0.1Ni0.1O3　(BZCYN)　barrier　layer　is　about　0.049　S/cm　at　600　degrees　C.　(C)　2021　Elsevier　B.V.　All　rights　reserved.