Arduino MKR NB 1500 - battery pack


I am fairly new to this community and related hardware. I am trying to design a panel with Arduino board. As per the specifications, the Arduino takes Li-Po Single Cell, 3.7V battery.

We are trying to have a battery life that can last longer than a single cell battery. can anyone advise If a battery pack contacting multiple cells will work for the application. Please provide me with your recommendations if you have done similar application.

Thank you!