Those are aluminum?
Aluminum is a poor material for battery connections because it corrodes so rapidly. If you anodized it, it wouldn't corrode, but it wouldn't conduct either. Also, it's probably 6061 which really doesn't like bending at all. 6061 will snap instead of bend.
Battery terminals...
mil style battery ends on Amazon. Copper crimp ends and heavy adhesive lined shrink tubing in black and red from Mcmasters. 2/0 USA made welding cable from my local welding wholesaler.
Mcmasters does not sell the mil style battery terminals otherwise I'd buy them there.