Li-Ion Conductivity Enhancement of LiBH4•xNH3 with In Situ Formed Li2O Nanoparticles

Interfacial engineering is an efficient approach to improve the ionic conductivity of solid-state electrolytes. In the present study, we report the enhancement of in situ formed nanocrystalline Li2O on the thermal stability and electrochemical properties of amide lithium borohydride, LiBH4 center dot xNH(3) (x = 0.670.8). LiBH4 center dot xNH(3)-Li2O composites with different amounts of Li2O are prepared by a one-step synthesis process by ball milling the mixture of LiBH4, LiNH2, and LiOH in molar ratios of 1:n:n (n = 1, 2, 3, 4). Owing to the strong interfacial effect with nanocrystalline Li2O, LiBH4 center dot xNH(3) is converted to the amorphous state in the presence of 78 wt % Li2O at n = 4. Consequently, the ionic conductivity of LiBH4 center dot xNH(3) at 20 degrees C is improved by orders of magnitude up to 5.4 x 10(-4) S cm(-1), the NH3 desorption temperature is increased by more than 20 degrees C, and the electrochemical window is widened from 0.5 to 3.8 V.

Automated summary

Interfacial engineering with nanocrystalline Li2O significantly enhances the ionic conductivity and thermal stability of LiBH4·xNH3. This leads to an expanded electrochemical window, increased NH3 desorption temperature, and orders of magnitude improvement in ionic conductivity at 20 degrees C.