Structural Characterization of Lithium Rich Layered Transition Metal Oxide LMR-NMC type Cathodes for Li-ion Batteries: Experimental and Computational Approaches
EMSL Project ID
48396
Abstract
Lithium ion batteries are the rechargeable battery system of choice in any high energy density application such as power tools, mobile electronics and electric vehicles. New cathode chemistries, such as Li-rich transition metal oxides (Ni, Mn, Co etc.) promise a greater energy density with significant cost reduction. Argonne high energy composite layered cathode xLi2MnO3.(1-x)LiMO2 (M = Ni, Mn, Co), also referred to as lithium and manganese rich NMC material (LMR-NMC), offers the potential for capacities exceeding 250 mAh/g, excellent cycle and calendar life, and outstanding abuse tolerance. However, these materials currently possesses a voltage fade issue (and other related issues) that affect its long-term cycle life and needs to be resolved. The as-made composite materials on first charge undergo a transformation, change in lithium ion local structure and rearrangement of underlying cations and possible changes in the oxidation state of manganese as well as possible oxygen removal from the lattice. This gradual rearrangement is believed to be tied to the voltage fade phenomena. Combination of multiple characterization techniques are required to follow and understand this important and complex structural transition. Solid state NMR, and specifically 6Li MAS NMR, is a well-established method, and has played an important role in determining and understanding the local order complexity in Li-rich transition metal (TM) oxides. Development and implementation of in-situ methodologies which have already contributed in understanding the nature of metastable phases and reactivity of systems of importance in the battery field such as the LiCoO2, Li-Si system, can also provide information on the dynamic species/local structures that might affect the electrochemistry of the related system. In addition to NMR, EPR spectroscopy is a unique local structure tool which directly monitors paramagnetic centers where NMR spectroscopy can only indirectly probe paramagnets via observing Li. The technique can be used to probe all transition metal oxidation state changes and correlate with all known and unknown electrochemical processes observed for these systems. Detailed analysis and assignments of new lithium/metal environments observed by NMR and EPR and the shifts mechanisms observed for the cycled systems are proposed to be studied with computational calculations.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2014-10-01
End Date
2016-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Han B., B. Key, A.S. Lipton, J. Vaughey, B. Hughes, J. Trevey, and F. Dogan. 2019. "Influence of Coating Protocols on Alumina-coated Cathode Material: Atomic Layer Deposition versus Wet-chemical Coating." Journal of the Electrochemical Society 166, no. 15:A3679-A3684. PNNL-SA-145484. doi:10.1149/2.0681915jes
Iddir H ,Key B ,Dogan Key F ,Russell J T,Long B R,Bareno J ,Croy J R,Benedek R 2015. "Pristine-State Structure of Lithium-Ion-Battery Cathode Material Li1.2Mn0.4Co0.4O2 Derived from NMR Bond Pathway Analysis" Journal of Materials Chemistry A 3(21):11471-11477. 10.1039/C5TA01510C