A positive electrode plate comprising a current collector, a positive active material layer and a safety coating disposed between the current collector and the positive active material layer, the safety coating comprising a polymer matrix and a conductive material, wherein the polymer matrix is fluorinated polyolefin and/or chlorinated polyolefin, and when the safety coating and the positive active material layer are collectively referred to as a positive film layer, the positive film layer comprises Na ions and/or K ions at a content of 100 ppm or more, and has an absorption peak at 1646 cm -1 in infrared absorption spectrum; wherein the polymer matrix is subjected to a crosslinking treatment which is achieved by introducing an activator and a crosslinking agent, and weight ratio of the activator to the polymer matrix is in the range of 0.5% to 5%, and weight ratio of the crosslinking agent to the polymer matrix is from 0.01% to 5%, the crosslinking agent is selected from at least one of polyisocyanates, polyamines, polyols, glycidyl ethers, inorganic substances, glyoxal, aziridine, organosilicons, benzenesulfonic acids, ethylenically unsaturated compounds, organic peroxides, and metal organic compounds, wherein the activator contains Na or K ions; wherein the role of the activator is to remove HF or HCl from fluorinated polyolefin and/or chlorinated polyolefin to form a C = C double bond and the role of the crosslinking agent is to crosslink the C=C double bond; and wherein parts of these C = C double bond remain and can be determined by the presence of an absorption peak at 1646 cm -1 in an infrared absorption spectrum; wherein the conductive material is selected from at least one of a conductive carbon-based material, a conductive metal material, and a conductive polymer material; and the inorganic filler is selected from at least one of metal oxides, non-metal oxides, metal carbides, non-metal carbides, and inorganic salts, all optionally modified with at least one of a conductive carbon coating, a conductive metal coating and a conductive polymer coating; and wherein the safety coating further comprises an inorganic filler, and based on the total weight of the polymer matrix, the conductive material and the inorganic filler being 100%, weight percentage of the polymer matrix is from 35 wt% to 75 wt%; weight percentage of the conductive material is from 5 wt% to 25 wt%; and weight percentage of the inorganic filler is from 10 wt% to 60 wt%. wherein the polymer matrix is subjected to a crosslinking treatment which is achieved by introducing an activator and a crosslinking agent, and weight ratio of the activator to the polymer matrix is in the range of 0.5% to 5%, and weight ratio of the crosslinking agent to the polymer matrix is from 0.01% to 5%, the crosslinking agent is selected from at least one of polyisocyanates, polyamines, polyols, glycidyl ethers, inorganic substances, glyoxal, aziridine, organosilicons, benzenesulfonic acids, ethylenically unsaturated compounds, organic peroxides, and metal organic compounds, wherein the activator contains Na or K ions; wherein the role of the activator is to remove HF or HCl from fluorinated polyolefin and/or chlorinated polyolefin to form a C = C double bond and the role of the crosslinking agent is to crosslink the C=C double bond; and wherein parts of these C = C double bond remain and can be determined by the presence of an absorption peak at 1646 cm -1 in an infrared absorption spectrum; wherein the conductive material is selected from at least one of a conductive carbon-based material, a conductive metal material, and a conductive polymer material; and the inorganic filler is selected from at least one of metal oxides, non-metal oxides, metal carbides, non-metal carbides, and inorganic salts, all optionally modified with at least one of a conductive carbon coating, a conductive metal coating and a conductive polymer coating; and wherein the safety coating further comprises an inorganic filler, and based on the total weight of the polymer matrix, the conductive material and the inorganic filler being 100%, weight percentage of the polymer matrix is from 35 wt% to 75 wt%; weight percentage of the conductive material is from 5 wt% to 25 wt%; and weight percentage of the inorganic filler is from 10 wt% to 60 wt%.