Are there lockers somewhere in Guangzhou Airport?

I am done with my study abroad semester and going to travel Beijing and Shanghai for 10 days. I am arriving back from shanghai at 6pm and on the same day at 11.30pm I am flying back to Germany. For domestic flights I can only take 20kg luggage+5kg carry-on luggage, but for international flights it´s 10kg more. I´d like to put these 10kg of clothes in a locker at Baiyun Airport for 10 days. Is that possible? And how much would it probably cost?
Thank you for your help!