The present invention provides a non-aqueous electrolyte secondary battery having high energy density and satisfactory cycle performance by using an alloy comprising Ni and Sn as a negative active material. The present disclosure improves upon low power Scan and Scan-BIST methods. The vertical portion of the angled members sufficiently extends above the planar top surface of the mattress to form a barrier to prevent the aforementioned accidents. If the proposed set-up would result in a interpenetration of teeth in opposing arches, such locations of interpenetration are illustrated in a contrasting color or shading.