Portable Power- 18650 Battery Shield for Raspberry Pi & Arduino
Amazon.com: diymore Double Li-ion V8 Battery Shield Micro USB 5V/3A 3V/1A Power Bank Battery Charging Module(2 Holders) : Electronics
ESP8266 ESP32 Dual 16340 Lithium Battery Charger Shield USB Mobile Power Bank Battery Holder Charger Board Module For Arduino|Instrument Parts & Accessories| - AliExpress
Programmable Lithium Charger Shield For Arduino | Hackaday
Overview | Adafruit PowerBoost 500 Shield | Adafruit Learning System
Adafruit PowerBoost 500 Shield - Rechargeable 5V Power Shield : ID 2078 : $19.95 : Adafruit Industries, Unique & fun DIY electronics and kits