Dual Layer Coating Strategy Utilizing N-doped Carbon and Reduced Graphene Oxide for High-Performance LiFePO4 Cathode Material

- LFP NP@NC@RGO is synthesized by utilizing a dual layer coating strategy.
- N-doped carbon layers along the LFP NP particles enhance the intrinsic conductivity of LFP.
- Due to the synergetic effect between N-doped carbon and RGO, the nanocomposite exhibits excellent electrochemical performance.
- The dual layer coating strategy can be used to enhance the electronic conductivity of other cathode materials.

Lithium iron phosphate (LiFePO4, LFP) has two major drawbacks such as low lithium ion diffusivity and poor electric conductivity, which limit the wider application as a cathode material for lithium ion batteries. In this work, we report a dual carbon layer coating strategy for LFP, which uses polydopamine-derived nitrogen-doped carbon (N-doped carbon) and reduced graphene oxide (RGO). These dual carbon layers are prepared by a one-pot polymerization process and thermal treatment. The dual carbon coated LFP has a rate capability with a discharge capacity of 98 mAh/g at 30C, cycling performance with a discharge capacity of 115 mAh/g at 10C, and 96.18% capacity retention after 700 cycles. The high rate performance and the excellent long-term cycling stability can be attributed to the enhanced electric conductivity with N-doped carbon coating, the well-connected electron pathway, and the fast Li+ ion diffusion induced by the small size of the particles. Consequently, coating of LFP with polydopamine derived N-doped carbon and RGO produces a material suitable for high-performance lithium-ion batteries.

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