CREATE TABLE table_204_583 (id DECIMAL, "capacitor type" TEXT, "capacity" TEXT, "volts" TEXT, "temp." TEXT, "energy-to-weight ratio" TEXT, "power-to-weight ratio" TEXT)

what comes after 2.7 volts
SELECT "volts" FROM table_204_583 WHERE id > (SELECT id FROM table_204_583 WHERE "volts" = 2.7 ORDER BY id DESC LIMIT 1) ORDER BY id LIMIT 1
SELECT "volts" FROM "table_204_583" WHERE "id" > (SELECT "id" FROM "table_204_583" WHERE "volts" = 2.7 ORDER BY "id" DESC NULLS LAST LIMIT 1) ORDER BY "id" NULLS FIRST LIMIT 1