luggage storage in the Beijing airport? Dont want to carry it all around.

In November I will be leaving China ( have been teaching here for a year) Before I leave I want to take a trip up to BJ/Xi'an and if i haven't gone yet Shanghai. Because I have to take all of my things out of my home before I leave I was wondering is there a place in the Capital airport, or somewhere that has a storage place near by there that I could store the luggage that I dont need while I'm In BJ other the lugging it all to the hotel and then back again a couple days later?