Which of the given compounds can enhance the efficiency of hydrogen storage tank?

We need to identify which compound can enhance the efficiency of a hydrogen storage tank.

For Option A, Li/P$$_4$$ is lithium with white phosphorus and is not a hydrogen storage material.

Option B, SiH$$_4$$ (silane or silicon tetrahydride), contains hydrogen and has been studied as a hydrogen storage material. Silicon-based hydrides can store hydrogen at high weight percentages and release it upon decomposition.

Option C, NaNi$$_5$$, is not a standard hydrogen storage alloy; the well-known alloy is LaNi$$_5$$, not NaNi$$_5$$.

Option D, di-isobutylaluminium hydride (DIBAL-H), is a reducing agent used in organic synthesis rather than a hydrogen storage material.

Among the given options, SiH$$_4$$ is the compound that can enhance hydrogen storage efficiency, as metal hydrides and silicon-based hydrides are important classes of hydrogen storage materials. The correct answer is Option B.