Place the sweet potato cubes, chickpeas, diced onion, and minced garlic in the slow cooker.
Sprinkle the curry powder, cumin, and salt over the vegetables and stir to coat everything evenly.
Pour in the vegetable broth and coconut milk, then stir once more to combine.
Cover and cook on low for 7 to 8 hours, until the sweet potatoes are soft enough to mash easily with a fork.
Stir the soup well to break up some of the sweet potatoes and thicken the broth.
Ladle into bowls and top with chopped cilantro. Serve lime wedges on the side.