Graphene-modified copper foil electrode used for power battery with silica-based cathode

Abstract

The invention discloses a graphene-modified copper foil electrode used for a power battery with a silica-based cathode. The copper foil electrode includes a copper foil base body, and the copper foilbase body is sequentially provided with a graphene buffering layer and an active material layer; the graphene buffering layer is formed on the copper foil base body and forms a flow gathering layer along with the copper foil base body; the active material layer is a silica-based alloy cathode coating layer, and the silica-based alloy cathode coating layer includes compound ingredients including C,Si, GeP5 and GeS, wherein the mass ratio of the compound ingredients including C, Si, GeP5 and GeS is (1-10):(1-10):(1-10):(1-10). The graphene-modified copper foil electrode has the advantages thatthe contact area between the flow gathering layer and the active materials is enlarged, and electronic migration potential barriers and interface internal resistance are reduced; the compatibility andbonding strength between the active materials and flow gathering bodies are enhanced; the physical, chemical and electrochemical properties are stable, and the stability of copper foil under an electrochemical condition and the battery safety are improved.

Description

technical field [0001] The invention relates to the technical field of lithium-ion battery electrodes, in particular to a graphene-modified copper foil electrode used for a silicon-based negative electrode power battery. Background technique [0002] The advent of the golden age of new energy vehicles has made power lithium-ion batteries the core of the current competition for new energy vehicles. In order to increase the mileage of electric vehicles, speed up the charging speed of vehicles, meet the power requirements of vehicle acceleration and climbing, further improve the energy density, power characteristics, cycle life of power lithium-ion batteries and reduce their manufacturing costs, it has become a challenge for the electric vehicle industry. urgent task. The charging speed and specific energy of existing power lithium batteries based on graphite negative electrodes are severely limited by the slow reaction kinetics and low theoretical specific capacity (372mAh / g)...

AI Technical Summary

Problems solved by technology

[0004] With the thorough progress of the alloying reaction of silicon-based negative electrode materials, the electrode materials will experience a series of irreversible structural changes and huge volume expansion (>300%) during the charging and discharging process, and the SEI film of silicon-based materials is also unstable. Under the action of volume change stress, the SEI film is constantly destroyed-reconstructed, resulting in a low Coulombic efficiency of its first charge and discharge, and poor compatibility with the positive electrode material in full battery applications, which can easily overcharge the positive electrode and cause the failure of the positive electrode material. irreversible damage

[0005] Secondly, silicon-based materials need to build special nanostructures and compound them with carbon materials to alleviate their volume expansion and increase their conductivity. Nanomaterials are prone to spontaneous agglomeration and slippage due to their small particle size and large specific surface area, making electrode preparation technology The difficulty is greatly increased: for example, it is difficult to disperse the material during pulping, and the spreadability of the slurry on the current collector is poor during coating; the bulk density of the material is low, and it contains a large amount of light carbon, and the bonding effect of the binder is not good. Cracks or shrinkage are easy to occur during the electrode drying process, powder is easy to fall off during rolling and slicing, and the tap density of the prepared electrode is low and it is difficult to reach the surface density level required by the industry

[0006] Thirdly, the volume change of silicon-based materials during charge and discharge causes the active material layer to be easily pulverized and fall off from the current collector, so that the internal resistance of the battery increases rapidly with the number of cycles, and the battery life decreases rapidly. What is more serious is that the active material After falling off from the current collector, the copper foil current collector will be exposed in the electrolyte. When the battery is overcharged or charged with a large current, it is easy to cause metal lithium to be directly precipitated on the copper foil, and the lithium dendrites generated will bring safety hazards. The copper current collector will be continuously corroded and dissolved by the electrolyte when it is over-discharged, resulting in irreversible damage to the battery cell

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