Abstract
High-energy-density Ni-rich Li[NixCoyAl1-x-y]O2 (NCA) is often chosen as the promising candidate for commercial EV batteries. However, the optimal synthesis method and Al concentration for fabricating high-performance NCA cathodes remain to be established. Al doping during coprecipitation facilitates the uniform incorporation of Al within the precursor particles through continuous feeding of the dopant during particle growth.1 On the other hand, supplying excess Al during calcination results in uneven distributions and induces segregation of Al along the grain boundaries.2 Herein, we provide an in-depth investigation of NCA cathodes prepared using coprecipitation and dry doping methods to focus on their different microstrcuture from spatial distribution of Al and the resulting properties. The homogeneous Al overdoping during coprecipitation did not provide additional drag force for grain consolidation, thereby producing near circular primary particles. By contrast, the heterogeneous Al distribution during dry doping retarded random grain coarsening, resulting in anisotropically grown primary particles with twinned crystal structures.3 Thus, Al heterogeneity induced the formation of spoke-like primary particles, which successfully dissipated the internal strain and allows NCA to retain 74.1% of its inital capacity after 1000 cycles in a full cell under sever operating conditions (3 C and 45 ℃), markedly improved the electrochemical performance of the cathode.
Published Version
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