10 year 9v battery for smoke detector

An alkaline 9V battery's shelf life (storage in excellent condition) will normally be around 10 years. A 9V battery's lifespan might vary depending on a number of variables. The battery's chemistry or quality and the load you are applying to it are what matter most. Battery life can go up to 5 years when used in applications that only use a small amount of energy. Battery life may be shortened by more demanding applications and unfavorable environmental factors like heat and dampness.