Multiple morphology composite cathode materials providing high energy and long cycle life and cells employing the same
Provided are electrochemically active composite materials that include a first particle comprising a first composition optionally of Li 1+a MO 2+b (Formula I) where −0.3≤a≤0.3 and −0.3≤b≤1.3 and where M optionally includes 30 at % to 80 at % Mn and 30 at % to 75 at % Ni, the first particle formed of a polycrystalline morphology having a plurality of crystallites and a grain boundary between adjacent crystallites; and a second particle comprising a second composition optionally of Li 1+c M′ 2 O 4+d (Formula II) where −0.1≤c≤0.3 and −0.2≤d≤0.2, wherein M′ comprises Mn at about 75 at % to about 100 at %, wherein said second composition or a portion thereof with a spinel structure and in the form of a three dimensional polyhedron; and wherein said second particle is within, on or about a surface of said first particle.
1. An electrochemically active composite material comprising: a first particle, which is a polycrystalline secondary particle defined by a first composition comprising Li 1+a MO 2+b (Formula I) where −0.3≤a≤0.3 and −0.3≤b≤1.3 and where M comprises Mn at 20 at % to 80 at % of total M and Ni at 30 at % to 75 at % of total M, said first composition formed of a polycrystalline morphology comprising a plurality of crystallites and a grain boundary between adjacent crystallites, said grain boundary with a layered α-NaFeO 2 -type structure, a cubic structure, or combination thereof, and
a second particle defined by a second composition comprising Li 1+c M′ 2 O 4+d (Formula II) where −0.1≤c≤0.3 and −0.2≤d≤0.2, wherein M′ comprises Mn at 75 at % to 100 at % of total M′, wherein said second composition or a portion thereof with a spinel structure and in the form of a three dimensional polyhedron;
wherein said second particle is on or about a surface of said first particle.
2. The electrochemically active composite material of claim 1 , wherein said second particle comprises a faceted polyhedral morphology.
3. The electrochemically active composite material of claim 1 , wherein said second particle has a particle size of 0.1 μm to 3 μm.
4. The electrochemically active composite material of claim 1 , wherein said second particle is present at 1 wt % to 15 wt % of said composite material.
5. The electrochemically active composite material of claim 1 , wherein the second particle comprises epitaxial growth marks, striation marks, or both.
6. The electrochemically active composite material of claim 1 , wherein M in said first composition comprises Ni, Mn and Co; and
M′ in said second composition comprises Mn and Ni.
7. The electrochemically active composite material of claim 6 , wherein M′ further comprises Ni.
8. The electrochemically active composite material of claim 6 , wherein Ni in M′ is present at 5 at % to 20 at % of total M′.
9. The electrochemically active composite material of claim 6 , wherein M′ comprises Ni present at 10 at % or greater of total M′, and said Mn in M is present at 45 at % to 65 at % of total M.
10. The electrochemically active composite material of claim 6 , wherein M′ further comprises Co.
11. The electrochemically active composite material of claim 10 , wherein said Co is present at greater than 0 at % to 15 at % of total M′.
12. The electrochemically active composite material of claim 6 , wherein M comprises Mn at 30 at % to 80 at %, Ni at 0 at % to 75 at %, Co at 0 at % to 15 at %, and/or Mg at 0 at % to 5 at %, or any combination thereof.
13. The electrochemically active composite material of claim 1 , wherein M comprises Mn at 30 at % to 80 at %, Ni at 30 at % to 75 at %, Co at 0 at % to 15 at %, and Mg at 0 at % to 5 at %.
14. The electrochemically active composite material of claim 1 , wherein said first particle has a particle size ranging from 1 μm to 25 μm.
15. The electrochemically active composite material of claim 1 , wherein said composite material has an overall composition of Li a Ni x Mn y Co z O b , wherein 1.18≤a≤1.4, 0.3≤x≤0.6, 0.45≤y≤0.65, 0≤z≤0.05, and 1.9≤b≤2.4.
16. The electrochemically active composite material of claim 1 , wherein Mn in said first composition is present at 45 at % to 65 at % of total M.
17. The electrochemically active composite material of claim 1 , wherein M comprises Ni at less than or equal to 40 at %.
18. The electrochemically active composite material of claim 1 , wherein M further comprises Co.
19. The electrochemically active composite material of claim 18 , wherein Co is present at greater than 0 at % to 10 at %.
20. The electrochemically active composite material of claim 1 , wherein M comprises Ni at 30-75 at %, Co at 0-15 at %, Mn at 30-80 at %, and additional elements at 0-10 at %.
21. The electrochemically active composite material of claim 1 , wherein M comprises Ni from 20 at % to 70 at %, Co from 0 at % to 30 at %, Al from 0 at % to 10 at %, and Mn from of 30 at % to 80 at %.
22. An electrochemical cell comprising a first electrode and a second electrode, the first electrode comprising the electrochemically active composite material of claim 1 , said first electrode further comprising a current collector in electrical contact with said electrochemically active composite material.
23. The electrochemical cell of claim 22 , wherein said second electrode comprises carbon or lithium titanate.
24. The electrochemical cell of claim 23 , wherein said second electrode comprises carbon, wherein said carbon comprises graphite.
25. The electrochemical cell of claim 24 , characterized by a discharge capacity of greater than 140 mAh/g over 400 cycles or more when cycled with (˜2 mAh/cm 2 cathode loading) cycled at 45° C. from 2.7-4.2 V with average C-rate >1.