Li3PO4-added garnet-type Li6.5La3Zr1.5Ta0.5O12 for Li-dendrite suppression

This paper proposes a strategy to stabilize the garnet/Li interface by introducing Li 3 PO 4 as an additive in garnet-type Li 6.5 La 3 Zr 1.5 Ta 0.5 O 12 . The Li 3 PO 4 -added Li 6.5 La 3 Zr 1.5 Ta 0.5 O 12 electrolyte exhibits a room-temperature Li-ion conductivity of 1.4 × 10 −4  S cm −1 , which is less than that of the Li 3 PO 4 -free counterparts (4.6 × 10 −4  S cm −1 ). However, the presence of Li 3 PO 4 improves the interfacial compatibility and suppresses Li-dendrite formation during Li-metal plating/stripping. The symmetric Li/garnet/Li cells with Li 3 PO 4 -added Li 6.5 La 3 Zr 1.5 Ta 0.5 O 12 have been successfully cycled at a current density of 0.1 mA cm −2 at 60 °C for 60 h; on contrast, the control cells with Li 3 PO 4 -free Li 6.5 La 3 Zr 1.5 Ta 0.5 O 12 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 Li 3 PO 4 to form a self-limiting and ion-conducting interphase, Li 3 P, which is confirmed experimentally.