Polymorphic lithium-silicon compound for use in pure silicon anode of lithium-ion battery and use thereof

A pure silicon anode of a lithium-ion battery, comprising a first polymorphic lithium-silicon compound and at least a second polymorphic lithium-silicon compound, wherein the first polymorphic lithium-silicon compound comprises

• a Li4.1Si_Cmcm having X-ray diffraction peaks at 2θ positions of 15.75±0.1 degree, 20.72±0.1 degree, 24.11±0.1 degree, 26.05±0.1 degree, 27.15±0.1 degree, 39.52±0.1 degree, 41.36±0.1 degree and 43.16±0.1 degree under a Cu target Kα X-ray radiation;
• and
• the second polymorphic lithium-silicon compound is selected from one or more groups consisting of a Li13Si4_Pbam, a Li2Si_C12/m1, and a LiSi_I41AZ, wherein:
• the Li13Si4_Pbam having X-ray diffraction peaks at 2θ positions of 12.33±0.1 degree, 20.72±0.1 degree, and 22.6±0.1 degree under the Cu target Kα X-ray radiation;
• the Li2Si_C12/m1 having X-ray diffraction peaks at 2θ positions of 14.05±0.1 degree and 23.61±0.1 degree under the Cu target Kα X-ray radiation;
• and
• the LiSi_I41AZ having X-ray diffraction peaks 20 positions of 18.77±0.1 degree and 19.28±0.1 degree under the Cu target Kα X-ray radiation.