IONICS
·
2020
·Vol. 27
·期 2
·657-666
·
IF 2.394
Hu Guorong,Liu Yanhua,Li Wei,Peng Zhongdong,Wu Jiahui,Xue Zhichen,Shi You,Fan Ju,Sun Qian,Cao Yanbing,Du Ke
P2-type Na 0.67 Ni 0.25 Mn 0.75 O 2 is considered as one of the most promising cathode materials for sodium-ion batteries due to its high initial capacity and operating voltage based on the Ni 2+ /Ni 4+ redox reaction. However, it suffers from rapid capacity decay caused by P2–O2 phase transition when the cutoff voltage is above 4.2 V (vs. Na + /Na). Herein, a high-voltage phase transition from P2 to an amorphous phase with poor crystallinity has been proved to be the main cause of material deterioration and Mn redox process is another cause. Cu-substituted Na 0.67 (Ni 0.25 Mn 0.75 ) 1−x Cu x O 2 ( x = 0, 0.05, 0.1, 0.2) with active redox couples of Ni 2+ /Ni 4+ and Cu 2+ /Cu 3+ has been fabricated for solving these issues. It is proved that Cu substitution can reduce the Mn 3+ /Mn 4+ reaction below 3 V (vs. Na + /Na) and suppress the high-voltage phase transition effectively at deep de-sodiated state, resulting in the significantly enhanced cycle life and rate capability of Na 0.67 Ni 0.25 Mn 0.75 O 2 .
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
ACS Sustainable Chemistry & Engineering
·
2024
·
IF 7.1
Rui Huang,Shaohua Luo,Pengyu Li,Qi Sun,Guodong Hao,Jie Feng,Lixiong Qian,Shengxue Yan,Jing Guo
Mn-rich ternary cathodes are highly regarded as a potential option for sodium-ion batteries (SIBs) due to their low cost and high theoretical capacity. Nonetheless, cycling stability was hindered by the occurrence of high-voltage phase transitions. In this work, Na0.67(Ni0.1Mn0.8Fe0.1)1–xMgxO2 (NaNMF-Mgx) cathode materials with high-voltage zero-phase transitions property were successfully synthesized. Amazingly, it was found that there was a valuable strengthening in the occupancy of stabler Nae sites by employing the Mg-doping strategy; and the calculation highlighted excellent structural stability and conductivity of NaNMF-Mg0.04, which has the lowest thermodynamic formation energy and a narrow band gap. The combination of theory and experiment demonstrated the underlying mechanisms of Mg substitution. Especially, Mg doping had the potential to regulate Nae/Naf ratio, and the ratio of NaNMF-Mg0.04 reached the maximum, indicating its most remarkable “rich-Nae” effect. Moreover, ex-situ XRD and ADF-STEM certified that NaNMF-Mg0.04 cathode maintained an intact P2 phase structure during high-voltage charging process. The “rich-Nae” and “zero-phase transitions” effects enabled NaNMF-Mg0.04 cathode to express remarkable initial capacitance (119.5 mAh g–1, 0.1 C), stability (80.0% over 200 cycles), and energy density (356.5 Wh kg–1). This unique mechanism provided fresh insights into revisiting the relationship between structure and performance and might open up a new idea for designing novel Mn-rich ternary cathodes with zero-phase transitions property in the future.
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF SOLID STATE ELECTROCHEMISTRY
·
2015
·Vol. 19
·期 6
·1827-1831
·
IF 2.446
Hou Junke,Song Jie,Niu Yubin,Cheng Chuanjun,He Hong,Li Yutao,Xu Maowen
P2-type Na 0.67 Ni 0.33 Ti 0.67 O 2 is explored as a titanium-based anode material for sodium ion batteries. The as-prepared Na 0.67 Ni 0.33 Ti 0.67 O 2 delivers a reversible capacity of 129.2 mAh g −1 at 0.05 C with smooth charge–discharge curves. A simple carbon-coating technique was used to improve the electronic conductivity of Na 0.67 Ni 0.33 Ti 0.67 O 2 particles. The carbon-coated Na 0.67 Ni 0.33 Ti 0.67 O 2 delivers a higher reversible capacity of 163.7 mAh g −1 and exhibits better rate capability than the as-prepared Na 0.67 Ni 0.33 Ti 0.67 O 2 .
研究领域:
电化学储能
·
无机非金属材料
·
能源材料
·
功能陶瓷
·
二次电池技术
✓ 已验证
DOI
高影响因子
JOURNAL OF POWER SOURCES
·
2017
·
IF 6.395
Wei-Lin Pang,Xiao-Hua Zhang,Jin-Zhi Guo,Jin-Yue Li,Xin Yan,Bao-Hua Hou,Hong-Yu Guan,Xing-Long Wu
Recently, sodium-ion batteries (SIBs) have been considered as the promising alternative for lithium-ion batteries. Although layered P2-type transition metal oxides are an important class of cathode materials for SIBs, there are still some hurdles for the practical applications, including low specific capacity as well as poor cycling and rate properties. In this study, the electrochemical properties of layered Mn-based oxides have been effectively improved via Al doping, which cannot only promote the formation of layered P2-type structure in the preparation processes but also stabilize the lattice during the successive Na-intercalation/deintercalation due to suppression of the Jahn-Teller distortion of Mn 3+ . Among the as-prepared series of Na 2/3 Mn 1- x Al x O 2 ( x = 0, 1/18, 1/9, and 2/9), Na 2/3 Mn 8/9 Al 1/9 O 2 with x = 1/9 exhibits the optimal doping effect with the best electrochemical properties, in terms of the highest specific capacity of 162.3 mA h g −1 at 0.1 C, the highest rate capability, and the best cycling stability in comparison to the undoped Na 2/3 MnO 2 and the other two materials with different Al-doped contents. Both cyclic voltammetry at varied scan rates and galvanostatic intermittent titration technique disclose the optimal electrode kinetics (the highest Na-diffusion coefficient) of the best Na 2/3 Mn 8/9 Al 1/9 O 2 .
研究领域:
材料科学
·
电化学
·
能源存储
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）