High-level pyrrolic-N-doped carbon coating concave hollow ZnO@C dodecahedrons for high-capacity lithium-ion batteries

Currently, conversion-type lithium-ion battery (LIB) anode materials suffer from low conductivity and poor Li ⁺ storage stability. Hence, g-C ₃N ₄-derived CN coating wrapped concave hollow ZnO@C dodecahedrons (ZnO@C@CN) were synthesized in this study and was used to address these challenges. The high-content pyrrolic-N-doped ZnO@C@CN-4 was precisely regulated by the solid-phase method, which can furnish complementary appearing defects, vacancies, and lithium storage sites. In addition, the CN coating and concave hollow structure improved the cycle stability and lithium storage capacity of the device. As LIBs anodes, the initial discharge specific capacity of ZnO@C@CN-4 was 1769.4 mA h g ⁻¹, and the reversible discharge capacity was 546.2 mA h g ⁻¹ after 1000 cycles at 1.0 A g ⁻¹. The rate performance data demonstrated that a capacity of 326.5 mA h g ^-1 capacity was achieved at a current density of 2.0 A g ⁻¹, and a high capacity of 678.1 mA h g ⁻¹ was still maintained after 100 cycles from high to low current. The design concept of this work can be extended to the other lithium storage materials and would also provide new insights into the regulation of nitrogen doping.