Kim Hjardar and Vegard Vike's Vikings at War is probably the best book available on Early Medieval Scandinavian warfare. It doesn't focus on battles specifically, although it does use several to illustrate points, but it provides a breakdown of how battles were fought, the types of weapons and equipment used and has a very detailed look at the various campaigns undertaken by Vikings. The illustrations are exceptional, there are plenty of maps, the scholarship is of a pretty high standard - although I do think they relied too much on taking the sagas at face value.

For the Vikings more generally, Andres Winroth's The Age of the Vikings is a highly readable overview designed for the general public, but written by a scholar. It's the best option available outside of some denser (and much more expensive) academic works.

I would also recommend Philip Line's The Vikings and Their Enemies: Warfare in Northern Europe, 750-1100, which is more critical of the sagas and has a good focus on the militaries of the people the Vikings fought, and Chris Wickham's The Inheritance of Rome, which is a general history of Early Medieval Europe and will help put the Scandinavians in context.