Xiaoning Li,Mengmeng Liu,Wenjuan Zhang,Yanli Zhang,Jiakun Zhou,Wenzhang Zhou,Naixin Wang,Weiwei Xu,Kehua Dai
O3-type NaNi0.4Fe0.2Mn0.4O2 cathode materials are structurally stable and have a high nickel content, allowing for stable high-capacity output. However, their performance needs further improvement. First, we investigated the effects of different sodium contents on the structure, morphology, and electrochemical performance of NaxNi0.4Fe0.2Mn0.4O2(x = 0.85, 0.9, 0.95, 1, 1.05) materials. The Na0.9Ni0.4Fe0.2Mn0.4O2 material exhibited initial discharge specific capacities of 148.11 and 181.80 mAh·g−1 at voltage ranges of 2–4.1 V and 2–4.2 V, respectively. To further optimize the cycling performance of the material, we doped NaNi0.4Fe0.2Mn0.4O2 with different calcium contents. Ca2+ doping significantly enhanced the electrochemical performance of the material. Subsequently, we synthesized Na0.96Ca0.02(NMF)0.95Zn0.05O2, and the dual-doped NMF-Ca0.02Zn0.05 maintains approximately 80% capacity retention at 1–4.05 V, and around 70% as the cut-off voltage increases to 4.15 V in full cells.
Xuan Luo,Luhan Wang,Meng Tian,Yi Tian,Xiao Zhang,Shijie Zhou,Jun Xie,Linlin Hu
O3-type layered oxides are considered ideal cathode materials for sodium-ion batteries (SIBs) owing to their high theoretical capacities, but these materials undergo complex phase transitions during the Na + extraction and insertion, resulting in serious structural degradation and reduced cycling stability. Herein, we employ “Cu/Mg co-doping strategy” to synthesize a stable O3-type layered transition metal oxide NaNi 0.25 Cu 0.1 Mg 0.05 Fe 0.2 Mn 0.4 O 2 (NaNCMFMO) with excellent structural reversibility. The resulting NaNCMFMO achieves reversible specific capacity of 123 mAh g −1 at 0.1 C and remarkable improvement in capacity retention of 79.4 % over 300 cycles at 1.0 C, compared to the pristine NaNi 0.4 Fe 0.2 Mn 0.4 O 2 cathode (42.1 % retention after 300 cycles). Additionally, ex situ X-ray diffraction pattern of NaNCMFMO indicates a highly reversible phase evolution of O3-P3-O3 during charge/discharge cycles, and GITT measurements reveal faster Na + diffusion kinetics. Moreover, a NaNCMFMO//hard carbon full-cell battery exhibits superior electrochemical performance: a high reversible specific capacity of 105.1 mAh g −1 at 1.0 C and capacity retention of 81.1 % over 200 cycles. This work presents a facile and effective strategy to suppress structural degradation in O3-type layered cathodes materials of high-performance SIBs.
Yu Zidong,Liu Xiaojuan,Liu Zhicheng,Liu Ye,Su Chao,Sun Zhi,Du Jilei,Wei Tao
Sodium-ion batteries (SIBs) have recently gained wildly interest due to the abundance of sodium, lower production costs, and better low-temperature performance compared to lithium-ion batteries (LIBs). Among various cathode materials of SIBs, O3-type NaNi 0.4 Fe 0.2 Mn 0.4 O 2 (NFM424) demonstrates high capacity and ease of synthesis, yet suffers from structural degradation and sluggish Na + kinetics caused by large ionic radius and strong electrostatic interactions. To overcome these issues, a configuration strategy combined with TiO 2 and Co 3 O 4 by a simple solid-state reaction method was introduced to improve structural and electrochemical stability. XRD, SEM, TEM, and various electrochemical characterizations as well as TGA/DSC tests were conducted. The resulting NaNi 0.4 Fe 0.2 Mn 0.3 Co 0.05 Ti 0.05 O 2 (NFMCT) cathode mitigated Jahn-Teller distortions and Na + /vacancy ordering while enhancing phase integrity and diffusion pathways. The obtained NFMCT maintained 93.7 mAh·g −1 after 550 cycles at 1 C, with superior rate capabilities at 2 C and 5 C. These findings deepen the understanding of configuration strategy by using multi-element oxide and highlight a practical strategy for designing high-performance SIB cathodes.
危险品化学品经营许可证（带存储）