iPod 4th Generation help

I’ve had it for almost 3 1/2 years if that helps. If I have wifi turned on and my brightness all the way down, the battery can last maybe 10/20 minutes. If I have the wifi on and the brightness up the battery can last 5 minutes max. When it says “20% battery” before I can even reach over to get the charger it turns off. Also, a bunch of my apps crash quite frequently. I’ve tried resetting it, turning off and back on. Nothing seems to solve any of my issues.