Anode active material and preparation method thereof, and device using the anode active material

An anode, comprising a current collector and anode active material, wherein the anode active material is coated on at least one surface of the current collector, wherein the anode active material comprising anode active particles having silicon element, a first conductive material and a second conductive material, wherein

• the first conductive material and the second conductive material form a three-dimensional conductive network structure;
• at least a portion of the anode active particles are accommodated in the three-dimensional conductive network structure;
• and
• a ratio of a total surface area of the first conductive material to a total surface area of the anode active particles is less than about 1000,
• wherein the first conductive material has a length to diameter ratio of about 50 to about 3000 and a diameter of about 2 nm to about 30 nm;
• the second conductive material has a length to diameter ratio of about 20 to about 500 and a diameter of about 50 nm to about 500 nm:
• the anode active particles have an average diameter D50 of about 0.5 μm to about 30 μm, and an average length L50 of the second conductive material and the D50 of the anode active particles satisfy:
• (L50−D50)/D50≥1, the L50 and the D50 being both in μm;
• and
• the first conductive material comprises carbon nanotubes containing at least one polar group, and the second conductive material comprises carbon fibers.

An electrochemical device, comprising:

• a cathode;
• an anode;
• a separator;
• and
• electrolyte,
• wherein the anode comprises anode active particles having silicon element, a first conductive material and a second conductive material, wherein
• the first conductive material and the second conductive material form a three-dimensional conductive network structure;
• at least a portion of the anode active particles are accommodated in the three-dimensional conductive network structure;
• and
• a ratio of a total surface area of the first conductive material to a total surface area of the anode active particles is less than about 1000,
• wherein the first conductive material has a length to diameter ratio of about 50 to about 3000 and a diameter of about 2 nm to about 30 nm;
• the second conductive material has a length to diameter ratio of about 20 to about 500 and a diameter of about 50 nm to about 500 nm;
• the anode active particles have an average diameter D50 of about 0.5 μm to about 30 μm, and an average length L50 of the second conductive material and the D50 of the anode active particles satisfy:
• (L50−D50)/D50≥1, the L50 and the D50 being both in μm;
• and
• the first conductive material comprises carbon nanotubes containing at least one polar group, and the second conductive material comprises carbon fibers.