Wemos D1 WiFi Module ESP WROOM 02

The development board integrates the ESP8266 18650 battery. A standard 3000mah 18650 battery can run for 17 hours or more.

Features:

• Compatible with nodemcu.
• 18650 charging system integration.
• LED indicator (green for full, red for charging) can be used while charging.
• Switch control power supply.
• SMT connector available for sleep mode
• Additional LED Programmable (gpio16)
• 0.5a charge current
• 1A output
• Overcharge protection
• Over discharge protection
• 10 digital pin read / write / interrupt / PWM / I2C / line support (except D0)
• The analog input should be careful "+ -".
• Packaged without battery. 

please note: If the positive and negative direction of the battery is placed incorrectly, the charging chip will be damaged.

You will require this 3.7V Lithium Ion battery.