All-solid-state batteries (ASSBs) are energy storage devices that use a solid electrolyte to facilitate ion transfer. Compared to conventional liquid-based battery designs, ASSBs offer several advantages, including improved safety by eliminating flammable liquid electrolytes and achieving higher energy density. In ASSBs, the electrodes consist of active particles embedded in a solid electrolyte matrix. During lithium intercalation, swelling of the active particles generates stresses within the electrodes, which can lead to degradation in the solid electrolyte and a subsequent reduction in battery performance. In this work, we present an optimization framework aimed at reducing damage potential by optimizing the shape and concentration of active particles in the electrode. A NURBS-based Interface-Enriched Generalized Finite Element Method (NIGFEM) is employed to capture both electrochemical and structural responses. In NIGFEM, material designs are parameterized using NURBS and projected onto a fixed, non-conforming mesh, enabling efficient and accurate representation of physical behavior. Gradient computations for optimization are performed analytically using the adjoint method. Finally, several example problems are presented, and a parametric and shape optimization study are conducted to demon- strate the effectiveness and versatility of the proposed approach.