The function of SLC9B2 (solute carrier family 9 member B2, Ensembl gene identifier ENSG00000164038) is as follows. Electroneutral Na(+) Li(+)/H(+) antiporter that extrudes Na(+) or Li(+) in exchange for external protons across the membrane (PubMed:18000046, PubMed:18508966, PubMed:22948142, PubMed:28154142, PubMed:36177733). Uses the proton gradient/membrane potential to extrude sodium (PubMed:22948142). Contributes to the regulation of intracellular pH and sodium homeostasis (By similarity). Also able to mediate Na(+)/Li(+) antiporter activity in kidney (PubMed:22948142). May play a physiological role in renal tubular function and blood pressure homeostasis (By similarity). Plays an important role for insulin secretion and clathrin-mediated endocytosis in beta-cells (By similarity). Involved in sperm motility and fertility (By similarity). It is controversial whether SLC9B2 plays a role in osteoclast differentiation or not (By similarity). {ECO:0000250|UniProtKB:Q5BKR2, ECO:0000269|PubMed:18000046, ECO:0000269|PubMed:18508966, ECO:0000269|PubMed:22948142, ECO:0000269|PubMed:28154142, ECO:0000269|PubMed:36177733}.