The challenges facing electric vehicles with respect to driving range and safety make the design of a lightweight and safe battery pack a critical issue.This study proposes a multifunctional structural battery system comprising cylindrical battery cells and a surrounding lightweight lattice metamaterial.The lattice density distribution was optimized via topological optimization to minimize stress on the battery during compression.Surrounding a single 18650 cylindrical battery cell,non-uniform lattices were designed featuring areas of increased density in an X-shaped pattern and then fabricated by additive manufacturing using stainless steel pow-ders.Compression testing of the assembled structural battery system revealed that the stronger lattice units in the X-shaped lattice pattern resisted deformation and helped delay the emer-gence of a battery short circuit.Specifically,the short circuit of the structural battery based on a variable-density patterned lattice was ～166％ later than that with a uniform-density lattice.Finite element simulation results for structural battery systems comprising nine battery cells indi-cate that superior battery protection is achieved in specially packed batteries via non-uniform lattices with an interconnected network of stronger lattices.The proposed structural battery systems featuring non-uniform lattices will shed light on the next generation of lightweight and impact-resistant electric vehicle designs.