Lithium-ion batteries (LIBs) are emerging as one of the most promising power sources for portable devices, as well as electric vehicles (EVs) and large energy storage systems (ESS), owing to their high energy density and excellent cycle life. However, the application of LIBs in EVs to reduce CO₂ emissions in internal combustion engine vehicles (ICEVs) involves some critical technical challenges, such as the driving range, safety, and cost concerns due to the properties of LIBs.^1-3 For this reason, research interests and industrial efforts have focused on developing low-cost, high-energy, and safe cathode materials, which are the main component determining LIB performance and cost. Transition metal layered oxides belonging to the LiNi_xCo_yAl_zO₂ (NCA) or LiNi_xCo_yMn_zO₂ (NCM) family, which can increase their intrinsic capacity (above 200 mAh g^-1) by increasing Ni content, are emerging as promising new cathode materials.⁴ However, the intrinsic drawbacks of Ni-rich cathodes, such as low Li intercalation stability over extended cycles, should be improved. In this study, we present the first successful boron doping strategy for a Ni-rich cathode material with very high Ni content. For the boron doping, we used a simple method where only a small amount of B₂O₃ was added during the calcination process. In addition, the structural and morphological stability of the boron-doped Ni-rich NCM cathode material was investigated before and after testing to evaluate the improved electrochemical performance; specifically, the significantly enhanced cycle performance. Thus, we conclude that the boron doping strategy is an effective and simple way to mitigate the poor stability problem of Ni-rich cathode materials for high-energy and stable LIBs.

References

1. D.-W. Jun, C. S. Yoon, U.-H. Kim, Y.-K. Sun, Chem. Mater. 2017, 29, 5048.
2. J. H. Lee, C. S. Yoon, J.-Y. Hwang, S.-J. Kim, F. Maglia, P. Lamp, S.-T. Myung, Y.-K. Sun, Energy Environ. Sci. 2016, 9, 2152.
3. S.-T. Myung, F. Maglia, K.-J. Park, C. S. Yoon, P. Lamp, S.-J. Kim, Y.-K. Sun, ACS Energy Lett. 2017, 2, 196.
4. K.-S. Lee, S.-T. Myung, K. Amine, H. Yashiro, Y.-K. Sun, J. Electrochem. Soc. 2007, 154, A971.