Chen Suo, Hou Jie, He Xin, Wang Qingyuan, Wang Wei, Zhou Min, Wang Kangli, Jiang Kai
State Key Laboratory of Materials Processing and Die & Mold Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China.
State Key Laboratory of Advanced Electromagnetic Technology, School of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China.
ACS Appl Mater Interfaces. 2024 Oct 2;16(39):52653-52662. doi: 10.1021/acsami.4c10821. Epub 2024 Sep 20.
Manganese-based NASICON-type compounds are promising as high-energy-density cathodes for sodium-ion batteries. However, the structural defects of Mn ions inside the crystal framework reduce the sodium storage capacity, voltage plateau, and cyclic stability of the cathodes. Here, a strategy to inhibit the Mn ion defects of NaMnCr(PO) has been proposed by using different phosphate sources. It is found that NaMnCr(PO) prepared with NHHPO (NMCP-N) exhibits less noticeable voltage hysteresis than that of NaMnCr(PO) prepared with HPO (NMCP-H), indicating that the site occupation defects of Mn ions in the NaMnCr(PO) crystal structure are successfully suppressed, as confirmed by theoretical calculations and structural refinements. In the case of NMCP-N, a capacity of 109.7 mAh g is delivered at 0.01 A g, and 54.2% capacity retention can be kept after 500 cycles at 0.5 A g, which is much better than that of the counterpart of NMCP-H (a lower capacity of 96.1 mAh g and poorer cyclability of only 22.8% capacity retention after 500 cycles), showing that the structure defects strongly affect the sodium storage properties of NaMnCr(PO) cathodes. This work provides an effective strategy to manipulate the structure defects of Mn-based NASICON-type cathode materials to enhance their electrochemistry.
锰基NASICON型化合物有望成为钠离子电池的高能量密度阴极材料。然而，晶体骨架内锰离子的结构缺陷会降低阴极的储钠容量、电压平台和循环稳定性。在此，通过使用不同的磷酸盐源，提出了一种抑制NaMnCr(PO)中锰离子缺陷的策略。研究发现，用NHHPO制备的NaMnCr(PO)（NMCP-N）比用HPO制备的NaMnCr(PO)（NMCP-H）表现出更不明显的电压滞后现象，这表明通过理论计算和结构精修证实，NaMnCr(PO)晶体结构中锰离子的占位缺陷得到了成功抑制。在NMCP-N的情况下，在0.01 A g电流密度下的容量为109.7 mAh g，在0.5 A g电流密度下循环500次后容量保持率为54.2%，这比NMCP-H的对应物（较低的容量为96.1 mAh g，500次循环后较差的循环性能，容量保持率仅为22.8%）要好得多，表明结构缺陷强烈影响NaMnCr(PO)阴极的储钠性能。这项工作提供了一种有效策略来控制锰基NASICON型阴极材料的结构缺陷，以增强其电化学性能。
