Defective Boron Nitride Inducing the Lithium-ion Migration on the Sub-Surface of LiBH_4

摘要

The safety issues oflithium-ion batteries provoke the development of highlysecure solidelectrolytes. Hydride electrolytes owning the high electrochemicalstabilityand anode compatibility may sufficiently relieve theconcerns of safety.However, the low ionic conductivity at room temperature hampersits furtherapplication. Herein, the strategy of defect-induced (BH_4)~– deformation toachieve high ionicconductivity LiBH_4/BN composite electrolyte is suggested.The theoreticalcalculations indicate that the volume of the (BH_4)~– tetrahedronis expanded by 14. Such atetrahedron deformation weakens the Li-Hinteraction forces in LiBH_4, and thus promotes the Li-ion migration. TheLiBH_4/BN composites are enabled to deliver lithium ionicconductivity of1.15 × 10~(-4) S cm~(-1) at 40 ℃ with a Li-ion transference number of 97, persuadingan excellent solidelectrolyte for all-solid-state batteries. The subsurfaceof LiBH_4 offers the lowest migration barrier among all possiblechannels,paving the optimal way for Li-ion migration. Furthermore, theLiBH_4/BN electrolytes supply excellent electrochemical stabilityand electrodecompatibility. The utilized strategy of outfield induction (notonly defects)and ligand deformation (not only (BH_4)~–) may also be extended to othersolid electrolytes.