Positive electrode plate, secondary battery and power consuming device

A positive electrode plate, comprising:

• a positive electrode current collector;
• a positive electrode film layer arranged on at least one surface of the positive electrode current collector;
• and
• a conductive undercoat layer positioned between the positive electrode current collector and the positive electrode film layer;
• wherein:
• the positive electrode film layer comprises a positive electrode active material comprising an inner core and a shell coating the inner core, wherein:
• the inner core has a chemical formula of Li1+xMn1−yAyP1−zRzO4 in which x is any value in a range of −0.100 to 0.100, y is any value in a range of 0.001 to 0.500, z is any value in a range of 0.001 to 0.100, A is one or more selected from the group consisting of Zn, Al, Na, K, Mg, Mo, W, Ti, V, Zr, Fe, Ni, Co, Ga, Sn, Sb, Nb, and Ge, R is one or more selected from the group consisting of B, Si, N, and S, and the values of x, y, and z satisfy that the entire inner core be electrically neutral;
• and
• the shell comprises a first coating layer coating the inner core, a second coating layer coating the first coating layer, and a third coating layer coating the second coating layer, wherein:
• the first coating layer comprises crystalline pyrophosphate LiaMP2O7 or Mb(P2O7)c in which 0≤a≤2, 1≤b≤4, and 1≤c≤6, with the values of a, b, and c satisfying that the crystalline pyrophosphate LiaMP2O7 or Mb(P2O7)c be electrically neutral, and M in each of the crystalline pyrophosphates LiaMP2O7 and Mb(P2O7)c is independently one or more selected from the group consisting of Fe, Ni, Mg, Co, Cu, Zn, Ti, Ag, Zr, Nb, and Al;
• the second coating layer comprises crystalline phosphate XPO4 in which X is one or more selected from the group consisting of Li, Fe, Ni, Mg, Co, Cu, Zn, Ti, Ag, Zr, Nb, and Al;
• and
• the third coating layer is carbon;
• and
• the conductive undercoat layer comprises a polymer, an aqueous binder, and a conductive agent, wherein the polymer comprises:
• a first monomeric unit represented by formula 1;
• a second monomeric unit including at least one selected from the group consisting of a monomeric unit represented by formula 2 and a monomeric unit represented by formula 3;
• a third monomeric unit including at least one selected from the group consisting of a monomeric unit represented by formula 4 and a monomeric unit represented by formula 5;
• and
• a fourth monomeric unit represented by formula 6, in which:
• R1, R2, and R3 each independently representing one or more of H, carboxyl, an ester group, and substituted or unsubstituted C1-C10 alkyl, C1-C10 alkoxy, C2-C10 alkenyl, and C6-C10 aryl, and
• R4 represents one or more of H and substituted or unsubstituted C1-C10 alkyl, C1-C10 alkoxy, C2-C10 alkenyl, and C6-C10 aryl;