Just found out that "Beyond the Brick" published some photos on Facebook (yes, Facebook): teardown/ the internals of the #LEGO #SmartBrick from the #SmartPlay ecosystem — with credits to "Images/Text by PsychologicalYak4619" (reddit user). The battery is a 3.7 V, 45 mAh Li-ion. The post also writes about "passive NFC tags".
#ReverseEngineering #HardwareHacking

Source: https://www.facebook.com/story.php?story_fbid=1512045446946885 / original reddit post: https://www.reddit.com/r/LegoSmartBrick/comments/1rkkojk/i_disassembled_a_smart_brick/