Is vowing to give away a ring as charity after divorce, due to anger at the husband, considered a "lajaj" vow?

The questioner's vow is not a vow of contention (nadhr al-lajaj), because she did not intend it to compel herself to do or refrain from something. A vow of contention is a vow by which the vower prevents himself from doing something or compels himself to do it by conditioning the commitment to an act of worship upon doing or refraining from something. Some jurists have mandated fulfilling the vow of contention and anger (nadhr al-ghadab), and they do not give the vower the choice between fulfilling it or offering an expiation for an oath (kaffarat al-yameen). This is narrated from Ali ibn Abi Talib, and it is the apparent narration from Abu Hanifa and the majority of his companions, and the well-known position of the Maliki school, and one opinion within the Shafi'i school.