A cyclic durable all-solid-state battery constructed with LiBH4-based electrolyte with high ionic conductivity at room temperature

LiBH 4 has been considered as a promising solid electrolyte for lithium-ion batteries. However, the low ionic conductivity at room temperature has been the biggest challenge of LiBH 4 solid-state electrolyte (SSE) toward practical solid-state batteries. In this work, a ternary electrolyte is designed and prepared by milling LiBH 4 with LiNH 2 and interfacially decorated with g-C 3 N 4 . It is revealed that the soft dispersed phase of two-dimensional g-C 3 N 4 can build an effective transportation network in the composite electrolyte, thereby decreasing the interfacial impedance and reducing the energy barrier for lithium ion diffusion. The optimized SSE, LiBH 4 -2LiNH 2 -g-C 3 N 4 -10 % (LBN-CN-10 %), exhibits an ionic conductivity of 1.5×10 −3 S cm −1 , five orders of magnitude higher than that of the LiBH 4 electrolyte at 30 °C. The LiIn symmetric cell with LBN-CN-10 % electrolyte delivers a low polarization of ∼89 mV over 10,000 h. When assembling with Li 4 Ti 5 O 12 cathode, the all-solid-state battery exhibits excellent cycling over 1000 cycles at 30 ℃, achieving a breakthrough in the lifetime of solid-state batteries with LiBH 4 -based electrolyte. Moreover, the all-solid-state battery with LiNi 0.8 Co 0.1 Mn 0.1 O 2 cathode also delivers a discharge plateau at 3.0 V, revealing the high voltage withstanding of LBN-CN-10 % electrolyte. This work provides new options for the development and practical application of room-temperature hydride all-solid-state batteries.