Battery alloy can be obtained from macerating LV batteries, which are made of tin and red alloy. When centrifuged, battery alloy dust provides antimony out of the thin air.
There are probably other ways too.

Agreed, we should replace the Macerator recipe with one that returns appropriate quantities of tin and red alloy dusts/piles.

This conflict is because the crafting table recipe was custom added, while the original recipe was removed. It is likely that the original recipe took battery alloy plates, which explains the battery alloy output. If this were to be adjusted to macerate tin and/or red alloy, then the recipe for the lv battery hull in the assembler would need to be adjusted to meet the crafting table recipe. This is becuase, while a custom recipe was added for the crafting table using new materials, the original assembler recipe was not touched, so it still uses battery alloy plate, tin cable, and polyethylene.

Agreed, the assembler recipe should be fixed as well.

To summarize the issue: a custom crafting table recipe was added for the LV battery hull, but this material change was not propagated to related machine recipes, resulting in a transmutation exploit.

TODO:

• remove the hull -> battery alloy macerator recipe
• add appropriate replacement for above
• remove the battery alloy/tin wire/PE -> hull assembler recipe
• add appropriate replacement for above