Structural changes in Si–CuSi films upon intercalation of lithium ions

We studied the possibility of using composite films representing amorphous silicon reinforced with crystalline inclusions of copper silicide as an anode material for lithium-ion batteries with liquid electrolyte. The films were made by layer-by-layer magnetron sputtering of amorphous silicon and copper, followed by low-temperature (100–200$^\circ$C) annealing of the structure. The tests of the anodes revealed the effect of prolonged intense growth of their reversible capacity. To describe the effect, a phenomenological model based on the multidirectional migration of silicon and copper atoms in an inhomogeneous field of elastic mechanical stresses arising during electrode cycling is proposed.