SIDE SILL ASSEMBLY FOR ECO-FRIENDLY VEHICLE

A side sill assembly for an eco-friendly vehicle protects a high voltage battery mounted therein from shock upon side collision. The side sill assembly includes: a center member fastened to a side surface of a center floor panel for a vehicle, a front outer member fastened to a front end of the center member , and a rear outer member fastened to the rear end of the center member , in which each of the center member , the front outer member , and the rear outer member has a cylindrical cross section and at least one partition wall for partitioning the inside thereof horizontally and vertically to absorb collision energy upon side collision.