Na(+)/H(+) antiporter that extrudes sodium in exchange for external protons. Can also transport lithium. Optimum pH is 8.0 for sodium and lithium transport. Exhibits Na(+)/H(+) and Li(+)/H(+) antiporter activity between pH 6.5 and 9.5. Belongs to the monovalent cation:proton antiporter 1 (CPA1) transporter (TC 2.A.36) family.