Lithium-ion batteries provide versatile energy storage for many applications including consumer electronics, transportation, and energy grids. Layered transition metal oxides provide a strong cathode material for lithium-ion batteries because they allow for more efficient and facile lithium diffusion with little resistance. Nickel-rich cathodes, such as LiNi0.8Mn0.1Co0.1O2 (NMC811), have the capability to provide high useable capacity if the challenges such as surface reconstruction, micro-cracking, oxygen evolution, and thermal instability can be overcome. We know that NMC811 has rapid surface changes that cause reduction of transition metals and possibly oxygen loss. Thus, using our knowledge of pure NMC811, adding a small amount of titanium (IV) has allowed us to synthesize a better performing cathode with high retentions and lower voltage drop. The titanium substitution limits voltage drops upon cycling, indicating that the elemental substitution method can effectively alleviate the structural changes that cause impedance growth. Our study also shows that the procedure of adding titanium (IV) during synthesis can drastically alter the final electrochemical properties of NMC811 materials. We performed multiscale spectroscopic and imaging characterization to probe the roles of titanium substitution in stabilizing the electronic and crystal structures of NMC811 materials. Our results suggest that adding the proper amount of titanium using the proper method and conditions allows titanium to benefit the NMC811 without sacrificing its useable capacity. Thus, the addition of titanium can help limit some of the nickel-rich challenges without sacrificing its key benefits of high useable capacity and working voltage. Finally, we conceive general design principles for developing nickel-rich NMC materials.

Stabilizing Ni-rich layered cathode materials via elemental substitution for high energy lithium batteries

255th National Meeting (2018)

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