Orange or turquise or even a pop of apple green would give it a boost! For a more subtle approach you could do a soft seafoam turq, a yellow gold, or a rust red.

A sleek chair and ottomon of cement gray may work with the black/charcoal/mushroom/white scheme. Accenting with tangerine adds warmth and plays into the contemporary elements. I think the space needs a palette; take a look at this photo and see all items fall into the grays, mushroom, and orange with a large contemporary bold artpiece at the wall. Also reduce the accessories outside the color palette and scheme.