My understanding of the halachic need for a gartel is very limited; is there any reason a woman should or should not wear one during prayer?
Assuming the reason for wearing a gartel is to prevent even accidentally one's heart from seeing one's private parts (which anyway must be covered to pray) as outlined in Alex's answer to the linked question, then it would seem there is no need for a woman to wear a gartel, as the Shulchan Aruch rules in OC 74:4 that due to their anatomical layout, women can never have the issue of her heart seeing her private parts. This ruling actually has a very practical outcome for many Ashkenazi women who recite a bracha on the mikva when standing naked in the water (cf. Shulchan Aruch YD 200 with Shach and Taz).
there is no need for women to wear a gartel. the reason for wearing a gartel has to do with the heart no seeing ones ervah but this is not an issue for women as they may say a brechah when in the not clothed in the mikvah. in addition there could be issues of beged isha if using what is commonly refereed to as a gartel