Improving Electrical Conductivity of LiFePO4 through Advanced Synthesis and Multidoping Techniques
Authors: Volobuyeva Valeriya , Tatykayev Batukhan , Umirov Nurzhan , Bakenov Zhumabay , Mentbayeva Almagul 
Published: August 2024

Extensive research has been conducted to enhance the electrical conductivity of LiFePO4. Several techniques, including doping with metal cations, synthesizing nanocrystalline grains, and carbon coating, have been employed [1]. Recent advances in material synthesis have revolutionized LiFePO4, such as depositing conductive carbon coatings on active material particles and exploring surface doping techniques. These advanced approaches have significantly improved the mass transfer rate [2]. High-capacity LiFePO4 materials close to the theoretical specific capacitance have been obtained.

Efforts are currently underway to improve the electronic and ionic conductivity of LiFePO4 to enhance its efficiency. However, before it can be widely used, the material's low electronic conductivity and suboptimal performance in high-speed regimes must be overcome. Doping with supervalent cations is an effective method for narrowing the energy gap and increasing the electrical conductivity of LiFePO4 [3]. Additionally, the synthesis of nanocrystalline grains and the deposition of conductive carbon coatings on the particle surface contribute to an increase in mass transfer rate, removing critical performance limitations of LiFePO4. Reducing the size of LiFePO4 to the nanoscale has been identified as a strategic method to shorten the diffusion length of Li-ions and accelerate electron-conducting pathways during charging and discharging cycles, ultimately improving the overall performance of the material.

This work compares the doping process of LiFePO4 cathode material using two methods: solid-phase synthesis in a planetary ball mill and spray pyrolysis in an inert gas atmosphere. The studies on the synthesis and modification of LiFePO4 have significant potential to overcome existing limitations and unlock its full potential for integration into high energy density batteries. The above multidoping methods enable the production of doped LiFePO4 materials with specific capacitance approaching theoretical values.

Acknowledgments

This research was funded by the Science Committee of the Ministry of Education and Science of the Republic of Kazakhstan (Grant No. AP19677233).

References

[1] Qiu, S., Zhang, X., Li, Y. et al. Facile synthesis and electrochemical performances of secondary carbon-coated LiFePO4-C composite for Li-ion capacitors based on neutral aqueous electrolytes. J Mater Sci: Mater Electron 27, 7255–7264 (2016). https://doi.org/10.1007/s10854-016-4692-1

[2] Xuetian Li, Lina Yu, Yonghui Cui, Axiang Li, Hongmei Shao, Zhongcai Shao, Wei Zhang, Zhongbao Shao, Enhanced properties of LiFePO4/C cathode materials co-doped with V and F ions via high-temperature ball milling route, International Journal of Hydrogen Energy, Volume 44, Issue 50, 2019, Pages 27204-27213, 0360-3199, https://doi.org/10.1016/j.ijhydene.2019.08.187.

[3] Xu, Z.; Gao, L.; Liu, Y.; Li, L. Review—Recent Developments in the Doped LiFePO4 Cathode Materials for Power Lithium Ion Batteries. J. Electrochem. Soc. 2016,163, A2600–A2610, http://dx.doi.org/10.1149/2.0411613jes

Figure 1