High capacity and stable cathode materials
High energy density cathode materials, such as LiNi X Mn Y Co Z O2 (NMC) cathode materials, with improved discharge capacity (hence energy density) and enhanced cycle life are described. A solid electrolyte, such as lithium phosphate infused inside of secondary particles of the cathode material demonstrates significantly enhanced structural integrity without significant or without any observable particle cracking occurring during charge/discharge processes, showing high capacity retention of more than 90% after 200 cycles at room temperature. In certain embodiments the disclosed cathode materials (and cathodes made therefrom) are formed using nickel-rich NMC and/or are used in a battery system with a non-aqueous dual-Li salt electrolytes.
1. A cathode material comprising:
LiNi X Mn Y Co Z O 2 (NMC) primary and secondary particles, wherein X+Y+Z=1; and
the secondary particles having lithium phosphate diffused within the secondary particles.
2. The cathode of claim 1 wherein the NMC is nickel-rich NMC and 0.95≥X≥0.5, Y is from 0.025 to 0.3 and Z is from 0.025 to 0.2.
3. The cathode material of claim 1 wherein the secondary particles further include a coating of lithium phosphate on an outer surface.
4. The cathode material of claim 3 wherein the lithium phosphate coating has been annealed prior to cycling the cathode in a battery system.
5. The cathode material of claim 3 wherein the secondary particles do not Include carbon and/or fluoride in mantles of the secondary particles after the cathode material is cycled at least 5 times in a lithium-ion or a lithium metal battery system.
6. The cathode material of claim 1 wherein the lithium phosphate is diffused at least into mantles of the secondary particles.
7. The cathode material of claim 1 wherein the lithium phosphate material is diffused into inner cores of the secondary particles.
8. The cathode of claim 1 wherein X is from 0.6 to 0.9, Y is from 0.1 to 0.2 and Z is from 0.07 to 0.15.
9. The cathode of claim 1 wherein X is from 0.65 to 0.85, Y is from 0.1 to 0.15 and Z is from 0.1 to 0.15.
10. The cathode material of claim 1 , wherein the NMC comprises LiNi 0.33 Mn 0.33 Co 0.33 O 2 , LiNi 0.5 Mn 0.3 Co 0.2 O 2 , LiNi 0.5 Mn 0.25 Co 0.25 O 2 , LiNi 0.52 Mn 0.32 Co 0.16 O 2 , LiNi 0.55 Mn 0.30 Co 0.15 O 2 , LiNi 0.58 Mn 0.14 Co 0.28 O 2 , LiNi 0.6 Mn 0.2 Co 0.2 O 2 , LiNi 0.64 Mn 0.18 Co 0.18 O 2 , LiNi 0.65 Mn 0.27 Co 0.08 O 2 , LiNi 0.7 Mn 0.2 Co 0.1 O 2 , LiNi 0.7 Mn 0.15 Co 0.15 O 2 , LiNi 0.72 Mn 0.10 Co 0.18 O 2 , LiNi 0.76 Mn 0.14 Co 0.10 O 2 , LiNi 0.8 Mn 0.1 Co 0.1 O 2 , LiNi 0.86 Mn 0.04 Co 0.10 O 2 , LiNi 0.9 Mn 0.05 Co 0.05 O 2 , LiNi 0.95 Mn 0.025 Co 0.025 O 2 , or any combination thereof.
11. The cathode material of claim 1 , wherein a cathode formed of the cathode material provides a discharge capacity greater than 200 mAh g −1 and retains at least 90% of its capacity after at least 150 cycles in a lithium-ion battery system.
12. A cathode comprising the cathode material of claim 1 wherein the secondary particles have a lithium phosphate concentration gradient wherein the lithium phosphate concentration in the secondary particles is greatest at outer regions of the secondary particles and lowest at inner regions of the secondary particles.