this paper proposes a strategy to stabilize the garnet/li interface by introducing li3po4 as an additive in garnet-type li6.5la3zr1.5ta0.5o12. the li3po4-added li6.5la3zr1.5ta0.5o12 electrolyte exhibits a room temperature li-ion conductivity of 1.4 x 10(-4) s cm(-1), which is less than that of the li3po4-free counterparts (4.6 x 10(-4) s cm(-1)). however, the presence of li3po4 improves the interfacial compatibility and suppresses li-dendrite formation during li-metal plating/stripping. the symmetric li/garnet/li cells with li3po4-added li6.3la3zr1.5ta0.5o12 have been successfully cycled at a current density of 0.1 ma cm(-2) at 60 degrees c for 60 h; on contrast, the control cells with li3po4-free li6.5la3zr1.5ta0.5o12 display noisy potential with large voltage polarization and get short-circuited completely after 33-h cycling under the same operating condition. the outstanding interface stability can be attributed to the in situ reaction of the li flux with li3po4 to form a self-limiting and ion-conducting interphase, li3p, which is confirmed experimentally. (c) 2017 elsevier b.v. all rights reserved.