This ESP8266 IoT board combines built-in USB and battery charging. The ESP8266 is clocked at 80 MHz and supports 3.3 V logic.
To make it easy to use for portable projects, a connector for 3.7 V Lithium polymer batteries and built in battery charging was added.
You don’t need a battery, it will run just fine straight from the micro USB connector. But, if you do have a battery, you can take it on the go, then plug in the USB to recharge. The board will automatically switch over to USB power when its available. The board comes pre-programmed with NodeMCU Lua.