Use of LiBr in organic synthesis?

An (educated hopefully) guess Br^- is a good nuleophile and will attack the Znδ+ center to give an intermediate of formula (-)Br....Znδ+(Br)...Rδ- (check my logic here) which makes the R group more easy to transfer to the Ni(0) center in the oxidative addition step. The lithium salt is used because it is more soluble in the organic solvent. (??)