Shelby Foote mentions in his Civil War history Robert E. Lee at the Battles of the Wilderness and Spotsylvania Courthouse suddenly decided he would personally lead a brigade in an attack. It happened 3 or 4 times. In all those instances the troops refused to attack until Lee went safety to the rear.
Do historians and biographers of Lee think that Lee wanted to die in battle rather than live and be defeated by Grant?
You do not need to hypothesize suicidal tendencies, in order for him to be acting that way. Foote has also said that when Lee's blood was up, you couldn't keep him from fighting. John Keegan has also noted that it was thought important that an officer was willing to expose himself to fire, in the early 19th century ( John Keegan : Mask of Command)