RAK7249 Battery Backup

Good afternoon! I have a rak7249 base station, there is only a board inside it, I want to make it work for a while when the power is turned off, I saw several articles with a battery and a board for charging and powering.
I want to buy only a set for UPS, I already have a base station.
Where can I buy this set? (ALIEXPRESS LINK PERFECT)