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MRS Spring Meeting 2017 in Phoenix, AZ

MRS Spring Meeting 2017 in Phoenix, AZ

Combining Li-Excess and Reversible Oxygen Charge Transfer to Achieve High Capacity Cathodes

Alexander Urban

April 20, 2017
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  1. Combining Li-Excess and Reversible Oxygen Charge Transfer to Achieve High

    Capacity Cathodes Alexander Urban, Jinhyuk Lee, Dong-Hwa Seo, Xin Li, Aziz Abdellahi, and Gerbrand Ceder Department of Materials Science and Engineering, University of California, Berkeley. [email protected] Phoenix, AZ, April 20, 2017 Download these slides at http://ceder.berkeley.edu
  2. Towards cathode materials with greater energy density Apr. 20, 2017

    Alex Urban - MRS Spring Meeting 2 Amount of electrons (= Li) per mass or volume that can utilized Voltage Potential difference between electrodes. Capacity Cathode material (positive electrode) is the bottleneck for capacity & voltage in LIBs. Capacity × Voltage = Energy Density
  3. Highest energy density cathodes are layered, but further improvement hard

    with layered structure Apr. 20, 2017 Alex Urban - MRS Spring Meeting 3 O3-type layered LiCoO2 -structure O TM Li LCO (Co) NCA (Ni, Co, Al) NCM (Ni, Co, Mn) Limited chemistry: Co, Ni, Mn, Al (no TM migration) Cannot utilize entire Li content Limited capacity: 140-200 mAh/g
  4. Need greater capacity for higher energy density Apr. 20, 2017

    Alex Urban - MRS Spring Meeting 4 Data from: Nitta et al., Materials Today 18 (2015) 252-264. Greater specific capacities needed Energy Density (Wh/kg)
  5. Apr. 20, 2017 Alex Urban - MRS Spring Meeting 6

    layered O3 disordered rocksalt J. Lee, A. Urban, X. Li, D. Su, G. Hautier, G. Ceder, Science 343 (2014) 519-522. Li1.211 Mo0.467 Cr0.3 O2 (LMCO) forms in layered structure but becomes cation disordered when cycled well-separated Li and TM layers intense cation mixing
  6. Cation-disordered LMCO has a remarkable capacity Apr. 20, 2017 Alex

    Urban - MRS Spring Meeting 7 1 Li per LiMO2 J. Lee, A. Urban, X. Li, D. Su, G. Hautier, G. Ceder, Science 343 (2014) 519-522. ~1 Li atom per LiMO2 formula unit can be reversibly cycled LiCoO2
  7. Fast (low-barrier) 0-TM channel Cation-disorder creates fast 0-TM diffusion channels

    that do not exist in stoichiometric layered materials Apr. 20, 2017 Alex Urban - MRS Spring Meeting 8 0-TM 1+ 1+ 2-TM 3+ 3+ 1-TM 1+ 3+ ? ? Cation disordered Layered
  8. Excess Li needed to increase 0-TM channel concentration Apr. 20,

    2017 Alex Urban - MRS Spring Meeting 9 The 0-TM channel concentration is just 6% in the stoichiometric LiMO2 Small concentration of 0-TM channels 0-TM channels = Locally Li-rich environment
  9. Apr. 20, 2017 Alex Urban - MRS Spring Meeting 10

    Layered Disordered Percolation threshold A. Urban, J. Lee, and G. Ceder, Adv. Energy Mater. 4 (2014) 1400478. One Li 0-TM cyclable at ~25 % Li excess Li1.211 Mo0.467 Cr0.3 O2 Around 10% Li excess enables 0-TM percolation in cation disordered structures 0-TM
  10. Impact on Li-ion battery cathode research 1991: Li3 V2 O5

    = Li1.2 V0.8 O2 C. Delmas, S. Brèthes and M. Ménétrier ω-Lix V2 O5 , J. Power Sources 34 (1991) 113-118. 1998: LiMO2 (M=Ti, Mn, Fe, Co, Ni) by mechanochemical synthesis (ball-milling) M. Obrovac, O. Mao, and J. Dahn, Solid State Ionics 112 (1998) 9-19. 2014: Li1.211 Mo0.467 Cr0.3 O2 J. Lee, A. Urban, X. Li, D. Su, G. Hautier, and G. Ceder, Science 343 (2014) 519-522. Apr. 20, 2017 Alex Urban - MRS Spring Meeting 11 2015: Li2 VO2 F = Li1.333 V0.666 O1.333 F0.666 R. Chen, S. Ren, M. Knapp, D. Wang, R. Witter, M. Fichtner, and H. Hahn, Adv. Energy Mater. 5 (2015) 1401814. 2015: Li1.3 Nbx M0.7-x O2 (M = Mn, Fe, Co, Ni) N. Yabuuchi, M. Takeuchi, M. Nakayama, H. Shiiba, M. Ogawa, K. Nakayama, T. Ohta, D. Endo, T. Ozaki, T. Inamasu, K. Sato, and S. Komaba, Proc. Natl. Acad. Sci. USA 112 (2015) 7650–7655. 2015: Li1.25 Nb0.25 Mn0.5 O2 R. Wang, X. Li, L. Liu, J. Lee, D.-H. Seo, S.-H. Bo, A. Urban, G. Ceder, Electrochem. Commun. 60 (2015) 70–73. 2015: Li1.2 Ni0.333 Ti0.333 Mo0.133 O2 J. Lee, D.-H. Seo, M. Balasubramanian, N. Twu, X. Li and G. Ceder, Energy Environ. Sci. 8 (2015) 3255–3265. 2015: Li1+x Ti2x Fe1-3x O2 S. L. Glazier, J. Li, J. Zhou, T. Bond and J. R. Dahn, Chem. Mater. 27 (2015) 7751–7756. 2016: Li1.333 Ni0.333 Mo0.333 O2 N. Yabuuchi, Y. Tahara, S. Komaba, S. Kitada and Y. Kajiya, Chem. Mater. 28 (2016) 416-419. 2016: Li1.3 Nb0.3 V0.4 O2 N. Yabuuchi, M. Takeuchi, S. Komaba, S. Ichikawa, T. Ozaki, and T. Inamasu, Chem. Commun. 52 (2016) 2051-2054.
  11. The new materials have high energy densities Apr. 20, 2017

    Alex Urban - MRS Spring Meeting 12 LCO, NMC, NCA data from: Nitta et al., Materials Today 18 (2015) 252-264. Energy Density (Wh/kg)
  12. The chemical space for disordered cathodes is much larger than

    for layered materials Apr. 20, 2017 Alex Urban - MRS Spring Meeting 13 Abundance data from: www.webelements.com (3/2017) A new opportunity space for Co-free cathodes
  13. Cation disorder is beneficial Cation mixing does not affect practical

    capacity for compositions with more than 15% Li excess Increased structural stability when delithiated enables very high capacities Much larger chemical space Apr. 20, 2017 Alex Urban - MRS Spring Meeting 14 A. Urban, J. Lee, and G. Ceder, Adv. Energy Mater. 4 (2014) 1400478. J. Lee, A. Urban, X. Li, D. Su, G. Hautier, G. Ceder, Science 343 (2014) 519-522.
  14. Capacity  Understanding the effect of cation disorder Apr. 20,

    2017 Alex Urban - MRS Spring Meeting 15 Understood conditions for high reversible capacities in DO-LiTMO2 Voltage How does cation disorder affect the voltage?
  15. Can disordered materials achieve high voltages? Apr. 20, 2017 Alex

    Urban - MRS Spring Meeting 16 LCO, NMC, NCA data from: Nitta et al., Materials Today 18 (2015) 252-264. Higher voltage desirable Energy Density (Wh/kg)
  16. Cation disorder can raise or reduce the voltage Apr. 20,

    2017 Alex Urban - MRS Spring Meeting 17 A. Abdellahi†, A. Urban†, S. Dacek, and G. Ceder, Chem. Mater. 28 (2016) 5659-3665. Cation disorder does not necessarily lead to low voltages
  17. Slope of voltage profiles depends on TM species Apr. 20,

    2017 Alex Urban - MRS Spring Meeting 18 Voltage (V) A. Abdellahi, A. Urban, S. Dacek, and G. Ceder, Chem. Mater. 28 (2016) 5373-5383. Small slope for High-V TMs
  18. Extra capacity beyond TM redox: oxygen redox enables very high

    capacity Li-excess cathodes Apr. 20, 2017 Alex Urban - MRS Spring Meeting 19 J. Lee, G. Ceder et al., Energy Environ. Sci. 8 (2015) 3255–3265. N. Yabuuchi et al., PNAS 112 (2015) 7650. R. Wang, G. Ceder et al., Electrochem. Commun. 60 (2015) 70–73. First observed in layered Li-excess materials Very common in cation disordered cathodes Li1.2 Ni1/3 Ti1/3 Mo2/15 O2 O redox Mn redox
  19. Clear change of oxygen K edge from oxygen redox Apr.

    20, 2017 Alex Urban - MRS Spring Meeting 20 R. Wang, G. Ceder et al., Electrochem. Commun. 60 (2015) 70–73.
  20. Relationship of cation disorder and oxygen redox Apr. 20, 2017

    Alex Urban - MRS Spring Meeting 21 • What is the origin of oxygen redox? • When does oxygen redox provide extra capacity beyond TM redox? • Are cation-disordered materials more likely to exhibit O redox?
  21. Conventional view: TM redox originates from antibonding M-O state Apr.

    20, 2017 Alex Urban - MRS Spring Meeting 23 M orbital O orbital bondi ng “O ” state anti bondi ng “M ” state e- Energy regular redox state
  22. M orbital O orbital bondi ng “O ” state Contribution

    from oxygen 2p regular redox state e- TM redox also exhibits some O contribution but that does not affect the capacity Apr. 20, 2017 Alex Urban - MRS Spring Meeting 24 Energy Ceder et al., Nature 392 (1998) 694. Extra capacity = utilize electrons from bonding states
  23. Strong M-O covalency impedes oxygen redox Apr. 20, 2017 Alex

    Urban - MRS Spring Meeting 25 Energy M orbital O orbital M orbital O orbital More Covalent Less Covalent Bonding state lowered  Electron is stabilized
  24. Stoichiometric layered materials possess only hybridized (covalent) oxygen states Apr.

    20, 2017 Alex Urban - MRS Spring Meeting 26 three Li-O-M e.g., stoichiometric layered Li-M oxides M bands O bands LiMO2 Li-O-M t1u * a1g * eg * t2g t1u b E eg b a1g b DH. Seo†, J. Lee†, A. Urban, R. Malik, SY. Kang, and G. Ceder, Nat. Chem. 8 (2016) 692-697.
  25. Lithium excess/cation disorder creates Li-O-Li configurations with unhybridized O states

    Apr. 20, 2017 Alex Urban - MRS Spring Meeting 27 one Li-O-Li, two Li-O-M e.g., Li-excess layered/cation-disordered Li-M oxides M bands O bands e.g., Li(Li1/3 M2/3 )O2 Li-O-Li Li-O-Li t1u * a1g * eg * t2g t1u b E eg b a1g b DH. Seo†, J. Lee†, A. Urban, R. Malik, SY. Kang, and G. Ceder, Nat. Chem. 8 (2016) 692-697.
  26. Lithium excess/cation disorder creates Li-O-Li configurations with unhybridized O states

    Apr. 20, 2017 Alex Urban - MRS Spring Meeting 28 DH. Seo†, J. Lee†, A. Urban, R. Malik, SY. Kang, and G. Ceder, Nat. Chem. 8 (2016) 692-697. M bands O bands e.g., Li(Li1/3 M2/3 )O2 Li-O-Li t1u * a1g * eg * t2g t1u b E eg b a1g b M orbital O orbital bonding O state anti-bonding M state unhybridized state (Li-O-Li)
  27. Accurate first-principles electron densities confirm the Li-O-Li mechanism Apr. 20,

    2017 Alex Urban - MRS Spring Meeting 29 DH. Seo†, J. Lee†, A. Urban, R. Malik, SY. Kang, and G. Ceder, Nat. Chem. 8 (2016) 692-697. 4 Li and 2 Ni 3 Li and 3 Ni 2 Li and 4 Ni Electron localized along Li-O-Li configuration 1 e- per LiNiO2 Yellow iso-surface: electron density The labile electron along the Li-O-Li configuration becomes redox accessible. Same mechanism for: Li(Ni,Mn)O2 , Li(Ru,Sn)O2 , Li(Ni,Ti,Mo)O2 , Li(Mn,Nb)O2
  28. Cation disorder & Li excess promote oxygen redox participation by

    creating Li-O-Li Apr. 20, 2017 Alex Urban - MRS Spring Meeting 30 Li M M M Li Li O Stoichiometric layered Li-M oxides (LiMO2 ) Li Li Li M M M O Li Li Li Li M M O Li-excess layered Li-M oxides (Li1.2 M0.8 O2 ) Li Li Li Li Li Li Li Li M M M O O Li Li Li Li M M O Li Li Li M M M O Li Li Li Li Li M M M M M M M O O Li-excess cation-disordered Li-M oxides (Li1.2 M0.8 O2 ) Li
  29. Statistically, at 15% Li excess every O atom in a

    cation disordered structure is part of an Li-O-Li bond Apr. 20, 2017 Alex Urban - MRS Spring Meeting 31 Probability of any O to be part of Li-O-Li x in Li1+x M1-x O2 Explains high O redox activity in cation disordered cathodes
  30. Summary Apr. 20, 2017 Alex Urban - MRS Spring Meeting

    32 High capacity through cation disorder • Cation disorder creates new type of fast 0-TM Li diffusion channel • 15% Li excess enables 0-TM Li percolation • Affects average voltage, voltage slope, and redox mechanism Extra capacity from oxygen redox • Oxygen redox originates from labile non-bonding oxygen states created by Li-O-Li configurations • Increased O-M covalency does not result in extra capacity • Li excess and cation disorder promote oxygen redox Lee, Urban, Ceder et al., Science 343 (2014) 519-522. Urban, Lee, Ceder, Adv. Energy Mater. 4 (2014) 1400478. Abdellahi†, Ur ban†, Dacek, Ceder, Chem. Mater. 28 (2016) 5659-3665. Abdellahi, Urban, Dacek, Ceder, Chem. Mater. 28 (2016) 5373-5383. Seo†, Lee†, Urban, Ceder et al., Nat. Chem. 8 (2016) 692-697. Seo, Urban, Ceder, Phys. Rev. B 92 (2015) 115118.
  31. Acknowledgments Apr. 20, 2017 Alex Urban - MRS Spring Meeting

    33 Jinhyuk Lee Xin Li (now Harvard U) Aziz Abdellahi (now at A123) Gerd Ceder Dong-Hwa Seo Ceder Group 2016