An ion-conducting composite electrolyte is provided comprising path-engineered ion-conducting ceramic electrolyte particles and a solid polymeric matrix. The path-engineered particles are characterized by an anisotropic crystalline structure and the ionic conductivity of the crystalline structure in a preferred conductivity direction H associated with one of the crystal planes of the path-engineered particle is larger than the ionic conductivity of the crystalline structure in a reduced conductivity direction L associated with another of the crystal planes of the path-engineered particle. The path-engineered particles are sized and positioned in the polymeric matrix such that a majority of the path-engineered particles breach both of the opposite major faces of the matrix body and are oriented in the polymeric matrix such that the preferred conductivity direction H is more closely aligned with a minimum path length spanning a thickness of the matrix body than is the reduced conductivity direction L.