Electrode active material, preparation method therefor, electrode comprising same and secondary battery
An electrode active material including a compound represented by Formula 1: Li x (Ni 1−y M y ) z (P 2 O 7 ) 4 <Formula 1> wherein in Formula 1, 5≤x≤7, 0.2≤y<1, 4≤z≤6, and M is a Group 3 to Group 11 element or a combination thereof, but is not iron.
1 . An electrode active material including a compound represented by Formula 1 and having a triclinic crystal structure:
Li x (Ni 1−y M y ) z (P 2 O 7 ) 4 <Formula 1>
wherein, in Formula 1, 5≤x≤7, 0.2≤y<1, 4≤z≤6, and
M is Co, Mn, V, Ti, Cr, Cu, Sc, Y, La, Zr, Hf, Nb, Ta, Mo, W, Re, or a combination thereof.
2 . The electrode active material of claim 1 , wherein in Formula 1, M is Co, Mn, V, Ti, Cr, Cu, Sc, or a combination thereof.
3 . The electrode active material of claim 1 , wherein in Formula 1, x is 5.5 to 6.5, or 5.8 to 6.2, y is 0.3 to 0.9, and z is 4.8 to 5.2, or 4.9 to 5.1.
4 . The electrode active material of claim 3 , wherein in Formula 1, x is 5.8 to 6.2, and z is 4.9 to 5.1.
5 . The electrode active material of claim 1 , wherein the compound represented by Formula 1 is one selected from compounds represented by Formulae 2 to 4:
Li x (Ni 1−y CO y ) z (P 2 O 7 ) 4 <Formula 2>
wherein in Formula 2, 5≤x≤7, 0.2≤y<1, and 4≤z≤6,
Li x (Ni 1−y Mn y ) z (P 2 O 7 ) 4 <Formula 3>
wherein in Formula 3, 5≤x≤7, 0.2≤y<1, and 4≤z≤6, or
Li x (Ni 1−y−a A a ) z (P 2 O 7 ) 4 <Formula 4>
wherein in Formula 4,
5≤x≤7, 0.2≤y<1, 4≤z≤6, 0<a≤0.2, and A is V, Nb, Ta, or a combination thereof.
6 . The electrode active material of claim 1 , wherein the compound represented by Formula 1 is Li 6 Ni 2 Co 3 (P 2 O 7 ) 4 , Li 6 Ni 3 Co 2 (P 2 O 7 ) 4 , Li 6 Ni 1 Co 4 (P 2 O 7 ) 4 , Li 6 Ni 4 Co 1 (P 2 O 7 ) 4 , Li 6 Mn 3 Ni 2 (P 2 O 7 ) 4 , Li 6 Mn 2 Ni 3 (P 2 O 7 ) 4 , Li 6 Mn 2 Ni 1 (P 2 O 7 ) 4 , Li 6 Mn 2 V 1 Ni 2 (P 2 O 7 ) 4 , Li 6 Mn 2 Nb 1 Ni 2 (P 2 O 7 ) 4 , Li 6 Mn 2 Ta 1 Ni 2 (P 2 O 7 ) 4 , Li 6 Tc 3 Ni 2 (P 2 O 7 ) 4 , Li 6 Re 3 Ni 2 (P 2 O 7 ) 4 , Li 6 Ni 2 Rh 3 (P 2 O 7 ) 4 , Li 6 Ni 1 Rh 4 (P 2 O 7 ) 4 , Li 6 Ni 2 Ir 3 (P 2 O 7 ) 4 , Li 6 Ni 1 Ir 4 (P 2 O 7 ) 4 , Li 6 Ni 2 V 3 (P 2 O 7 ) 4 , Li 6 Ni 1 V 4 (P 2 O 7 ) 4 , Li 6 Ni 2 Nb 3 (P 2 O 7 ) 4 , Li 6 Ni 1 Nb 4 (P 2 O 7 ) 4 , Li 6 Ni 2 Ta 3 (P 2 O 7 ) 4 , Li 6 Ni 1 Ta 4 (P 2 O 7 ) 4 , Li 6 Co 2 V 1 Ni 2 (P 2 O 7 ) 4 , Li 6 Co 2 V 2 Ni 1 (P 2 O 7 ) 4 , Li 6 Ti 3 Ni 2 (P 2 O 7 ), Li 6 Cr 3 Ni 2 (P 2 O 7 ) 4 , Li 6 Cu 3 Ni 2 (P 2 O 7 ) 4 , Li 6 Sc 3 Ni 2 (P 2 O 7 ) 4 , or a combination thereof.
7 . The electrode active material of claim 1 , wherein the compound of Formula 1 exhibits a main peak in a region of a diffraction angle 2θ of 28.5=2°, as measured by X-ray diffraction analysis with CuKα radiation.
8 . The electrode active material of claim 1 , wherein the compound of Formula 1 has a ratio (P2/P1) of minor peak intensity (P2) to main peak intensity (P1) of 0.4 or less, as measured by X-ray diffraction analysis with CuKα radiation.
9 . The electrode active material of claim 1 , wherein the compound of Formula 1 has a triclinic crystal structure and a space group p-1.
10 . An electrode comprising the electrode active material of claim 1 .
11 . A secondary battery comprising an electrode including the electrode active material of claim 1 .
12 . The secondary battery of claim 11 , wherein the electrode is a positive electrode, and the electrode active material is a positive electrode active material with a voltage of 4.8V or more with respect to lithium.
13 . The secondary battery pf claim 12 , wherein in a dQ/dV charge/discharge differential curve of the battery, a dQ/dV peak voltage at which a maximum discharge curve area appears in a voltage range of 3.0V to 5.5V at a current of 0.025 C is 4.7 V or higher with respect to Li/Li + .
14 . The secondary battery of claim 12 , wherein in a dQ/dV charge/discharge differential curve of the battery, a ratio (A2/A1) of an area (A2) of a discharge curve at 4.7V to 5.5V to an area (A1) of a discharge curve at 3.5V to 5.5V under conditions of a voltage of 3.0V to 5.5V is 0.4 or more.
15 . The secondary battery of claim 12 , wherein the secondary battery is a lithium secondary battery or an all-solid-state battery.
16 . The secondary battery of claim 11 , is an all-solid-state multilayer ceramic (MLC) battery, or an all-solid-state thin-film battery.
17 . The secondary battery of claim 11 , wherein the battery is an all solid-state multilayer ceramic battery has-including a laminate structure in which a plurality of cell units, each including, sequentially in the stated order,
a positive electrode layer including a positive electrode active material layer,
a solid electrolyte layer, and
a negative electrode layer including a negative electrode active material layer,
wherein the positive electrode layer including the positive electrode active material layer, the solid electrolyte layer, and the negative electrode layer including the negative electrode active material layer, are stacked such that the positive active material layer and the negative electrode active material layer face each other.
18 . The secondary battery of claim 11 , wherein the battery is an all soil-state multilayer ceramic battery including a laminate in which a plurality of unit cells, each including, sequentially in the stated order,
a positive electrode active material layer,
a solid electrolyte layer, and
a negative electrode active material layer,
wherein the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer, are stacked such that the positive active material layer and the negative electrode active material layer of adjacent unit cells face each other.
19 . The secondary battery of claim 11 , wherein the secondary battery is an all-solid-state secondary battery comprising: a positive electrode layer including a positive electrode active material layer; a negative electrode layer including a negative electrode current collector layer and either a first negative electrode active material layer or a third negative active material layer; and a solid electrolyte layer arranged between the positive electrode layer and the negative electrode layer, and
the positive electrode active material comprises a positive electrode active material including a compound represented by Formula 1:
Li x (Ni 1−y M y ) z (P 2 O 7 ) 4 <Formula 1>
wherein in Formula 1, 5≤x≤7, 0.2≤y<1, 4≤z≤6, and
M is Co, Mn, V, Ti, Cr, Cu, Sc, Y, La, Zr, Hf, Nb, Ta, Mo, W, Re, or a combination thereof.
20 . The secondary battery of claim 19 , wherein the first negative electrode active material layer comprises one or more selected from a carbonaceous negative electrode active material and a metal or metalloid negative electrode active material.
21 . The secondary battery of claim 20 , wherein the carbonaceous negative electrode active material comprises one or more selected from amorphous carbon and crystalline carbon, and
the metal or metalloid negative active material is one or more selected from the group consisting of gold, platinum, palladium, silicon, silver, aluminum, bismuth, tin, and zinc.
22 . The secondary battery of claim 19 , wherein
the all-solid-state secondary battery further comprises a negative electrode current collector, and
a second negative electrode active material layer arranged at least one of between the negative electrode current collector and the first negative electrode active material layer, and between the solid electrolyte layer and the first negative active material layer, and
the second negative electrode active material layer is a metal layer including lithium or a lithium alloy.
23 . The secondary battery of claim 19 , wherein the third negative electrode active material layer is a metal layer including lithium or a lithium alloy.