Can I replace the broken battery terminal?

@lorid46982 this does luckily not look like a major structural component. I would suggest a good two part epoxy. Something like J-B Weld Epoxy Putty or Loctite's Plastic bonder. The paste is usually better for this, since you can apply it within the fracture of the plastic pieces and a couple of layer across the top. To add some structural strength get a strip of the fiberglass mesh repair patches and embed that where you place the putty. Something like a layer of putty followed with a strip or two of the mesh, followed by another layer of putty.