The fragrance of the grated lemon rind (= lemon zest) can not be substituted by lemon juice in a cooking receipe. Lemon juice has a prickly sour taste and only a very slight, sometimes flowery fragrance. Lemon zest has a very strong lemony scent but a rather bitter or bitter/oily taste.
If you don't have lemon zest for a cake, put something different like brandy, rum or cardamon powder.