Gu Mubao, Chen Shiqi, Xu Junling, Shi Xiaoyan, Shao Lianyi, Sun Zhipeng
School of Materials and Energy, Guangdong University of Technology, Guangzhou 510006, China.
ACS Appl Mater Interfaces. 2025 Apr 16;17(15):22546-22556. doi: 10.1021/acsami.4c21797. Epub 2025 Apr 6.
Layered oxides are considered promising cathode materials for sodium-ion batteries (SIBs) due to their high energy density, flexible compositions, and low cost. However, they encounter significant challenges, such as multiphase transitions and structural instability at high voltages, which limit their large-scale practical application. In this study, we employed a dual modification strategy involving complex composition doping and phosphate coating to fabricate the NaNiMn(TiMgCuZn)O@phosphate cathode (D-NNM). The lattice distortion induced by complex composition doping optimizes the overall properties of the cathode, while the phosphate coating forms a robust electrode interface through stable P-O bonds. This comprehensive modification strategy stabilizes phase transitions and interfacial structure, thereby enhancing Na transport and mitigating mechanical degradation and surface reactions at high voltages. Consequently, D-NNM exhibited an initial capacity of 136.9 mA·h·g with an average potential of 3.45 V and maintained 85% capacity after 60 cycles at 4.4 V, twice that of the pristine cathode. D-NNM demonstrated faster Na diffusion kinetics at high voltage without any significant particle cracks observed even after 50 cycles. This strategy offers comprehensive protection for layered oxides from bulk to surface and provides insights into the design of high energy density cathodes for SIBs.
层状氧化物因其高能量密度、灵活的成分和低成本，被认为是钠离子电池（SIB）很有前景的正极材料。然而，它们面临重大挑战，如在高电压下的多相转变和结构不稳定性，这限制了它们的大规模实际应用。在本研究中，我们采用了一种双重改性策略，包括复杂成分掺杂和磷酸盐包覆，来制备NaNiMn(TiMgCuZn)O@磷酸盐正极（D-NNM）。复杂成分掺杂引起的晶格畸变优化了正极的整体性能，而磷酸盐包覆通过稳定的P-O键形成了坚固的电极界面。这种综合改性策略稳定了相变和界面结构，从而增强了Na传输，并减轻了高电压下的机械降解和表面反应。因此，D-NNM在平均电位为3.45 V时的初始容量为136.9 mA·h·g，在4.4 V下循环60次后保持了85%的容量，是原始正极的两倍。D-NNM在高电压下表现出更快的Na扩散动力学，即使在50次循环后也未观察到明显的颗粒裂纹。该策略为层状氧化物提供了从体相到表面的全面保护，并为SIBs高能量密度正极的设计提供了思路。
