Once the question turns into star systems instead of asteroids, the answer is: lift hydrogen out of stars and transmute it into lithium as needed. Resources are

Once the question turns into star systems instead of asteroids, the answer is: lift hydrogen out of stars and transmute it into lithium as needed. Resources are heterogeneous only for civilizations significantly below level of 2 on the Kardashev's scale. Above it's all just matter-energy.