Nanocrystalline Ni3Sn4 alloy powders prepared by high energy ball milling are examined as an anode for lithium-ion batteries. Ex situ X-ray diffraction (XRD) and differential capacity plots show that crystalline Ni3Sn4 has a low affinity for lithium. In the case of well-developed nanocrystalline Ni3Sn4, the lithium atoms reversibly react with tin atoms in the grain boundaries with no capacity fading for extended cycling.