Hi Moufdi,
We're glad to help! The Efest Purple IMR26650 3500mAh 3.7V 32A High Drain Battery will not work with the SX Mini, because the SX Mini accepts 18650 batteries, and the 26650 will be too large. I'm posting a link to a battery that will work great with your SX Mini below.
http://www.smoktek.com/Efest-Purple-IMR18650-3000mAh-37V-35A-High-Drain-Battery--Flat-Top_p_1388.html
Best regards,
Brad