Effects of Defective Boron Nitride Additives on Lithium-Ion Conductivity and Hydrogen-Desorption Properties of LiAlH₄

Abstract

The lithium-ion conductivity and hydrogen-desorption properties of lithium alanate (LiAlH 4 )/boron nitride (BN) composites were investigated. The effects of boron nitrides with different structures (hexagonal (h-BN), turbostratic (t-BN), and cubic (c-BN)) on the properties were demonstrated. Compared with milled LiAlH 4 , the ion conductivity was improved in the h-BN and t-BN composites. Among the composites, the t-BN composite showed the highest conductivity and lowest activation energy (E a ) for ion conduction. In the 40 wt % t-BN composite, the conductivity at 80 °C reached as high as 1.1 × 10 −3 S cm −1 . Impedance plots that correspond to the interfacial conductivity were observed, which implies the appearance of LiAlH 4 /t-BN interfacial ion conduction. Ball-milling of LiAlH 4 with BN caused the partial replacement of aluminum with boron to form LiBH 4 phase, which would cause the E a decrease. The LiAlH 4 melting and hydrogen-desorption temperature decreased in the t-BN composite. In the c-BN composite, a large amount of stainless steel impurity during ball-milling caused desorption without melting. This study suggests that the addition of defective boron nitride like t-BN can be a useful strategy to improve the lithium-ion conductivity of complex hydrides. The t-BN additive effects on the hydrogen-desorption properties, which are different from transition metal catalysts, were also demonstrated.

Defective Boron Nitride Inducing the Lithium‐ion Migration on the Sub‐Surface of LiBH4

“…[42] Defective BN can provide sufficient defects for inducing ion migration, as well as desirable stability and ultra-high electronic resistance if forming composite electrolytes with LiBH 4 . [43] For these reasons, LiBH 4 was combined with defective hexagonal BN (d-BN for short) in the present work by ballmilling and subsequent heating where a significant improvement of Li-ion conductivity (10 -4 S cm -1 ) at RT was achieved. It is in the same level as the current frontier of LiBH 4 composite electrolyte.…”

“…[ 42 ] Defective BN can provide sufficient defects for inducing ion migration, as well as desirable stability and ultra‐high electronic resistance if forming composite electrolytes with LiBH 4 . [ 43 ]…”

Enhanced Hydrogen Storage Properties of LiAlH4 by Excellent Catalytic Activity of XTiO3@h‐BN (X = Co, Ni)

“…Meanwhile, some reports also proposed that h ‐BN would enhance the Li‐ion mobility across the interface of the lithium‐containing hydrogen storage system. [ 53 ] Therefore, the introduction of NiTiO 3 and h ‐BN may synergistically enhance the rehydrogenation behaviors of LiAlH 4 .…”

Enhanced Li-ion conductivity in LiBH4–ZrO2 nanocomposites and nanoscale Li imaging by energy-filtered transmission electron microscopy

“…The former peak was attributed to [B(OH) 4 ] species 20 and the latter peak originated from amorphous B–O species. 9 Unlike pristine LiBH 4 , the amount of amorphous B–O species increased in the nano ZrO 2 composite. The formation of B–O species was also confirmed in other LiBH 4 –oxide nanocomposites.…”

“…[1][2][3] Solid-state electrolytes are promising alternatives because they have a relatively high Li + transference number, high stability over a wide temperature range, and high energy density. [1][2][3] Among the various types, complex hydride Li-ion conductors, such as LiBH 4 , 4,5 Li 2 B 12 H 12 , 6,7 and LiAlH 4 , 8,9 represent a new class of solid electrolytes. Lithium borohydride (LiBH 4 ) is one of the well-studied complex hydride Li-ion conductors.…”