Batteries + Bulbs is a reputable retail store chain that sells batteries for many electronic devices.
Amazon and Newegg are a good online options. I have included a couple of links you can check out. These batteries are by JIAZIJIA and Dentsing, and they have gotten pretty good reviews.
[https://www.amazon.com/JIAZIJIA-Compatible-Battery-Precision-Notebook/dp/B07HQFW16H|https://www.amazon.com/JIAZIJIA-Compatible-Battery-Precision-Notebook/dp/B07HQFW16H]
[https://www.amazon.com/Dentsing-H5H20-battery-Precision-56WHR/dp/B07687C76W|https://www.amazon.com/Dentsing-H5H20-battery-Precision-56WHR/dp/B07687C76W]