Boron & nitrogen synergistically enhance the performance of LiNi0.6Co0.1Mn0.3O2

Nickel-rich ternary material faces up with the performance degradation problem associated with its poor structural stability and interfacial side reactions with the electrolyte. Herein, boron and nitrogen co-modified LiNi0.6Co0.1Mn0.3O2 material was synthesized, aiming at studying the effect on the crystal structure, electronic conductivity and the electrochemical performance. It is interesting to find out that the rate performance and the cycle stability of the B&N co-modified materials are greatly associated with the ratio of B/N. The optimal sample NCM/B4N4 has initial specific discharge capacity 198.4 mAh g−1, the retention of 81.3% after 200 cycles (1 C) as well as the electronic conductivity of 5.00 × 10−4 S/cm, against the pristine NCM (194.0 mAh g−1, 56.7%, 1.22 ×10−4 S/cm). Moreover, the discharge capacity of the modified sample is improved obviously at high rate (5 C). TEM and XPS show that boron and nitrogen were successfully doped into the surface of the materials. Compared the PXRD patterns after 300 cycles and in situ XRD tests, it is found that the boron and nitrogen co-modification can inhibit the irreversible phase transition. DFT calculations disclose that Li layer thickness of the B&N co-doped sample is larger than that in individual B doped sample and the pristine material. GITT test confirms the higher lithium ions diffusion rate of NCM/B4N4. This work suggests that Nitrogen-doping can improve the electronic conductivity of Boron-doped material, consequently facilitating the Li ion diffusion of nickel-rich cathode materials.