Wang Dongdong, Yan Qizhang, Li Mingqian, Gao Hongpeng, Tian Jianhua, Shan Zhongqiang, Wang Ning, Luo Jian, Zhou Meng, Chen Zheng
Department of NanoEngineering, University of California San Diego, La Jolla, CA 92093, USA.
Nanoscale. 2021 Feb 7;13(5):2811-2819. doi: 10.1039/d0nr08305d. Epub 2021 Jan 28.
Nickel (Ni)-rich layered oxides such as LiNiCoMnO (NCM622) represent one of the most promising candidates for next-generation high-energy lithium-ion batteries (LIBs). However, the pristine Ni-rich cathode materials usually suffer from poor structural stability during cycling. In this work, we demonstrate a simple but effective approach to improve the cycling stability of the NCM622 cathode by dry coating of ultrastable LiV(PO)-carbon (LVP-C) nanoparticles, which leads to a robust composite cathode (NCM622/LVP-C) without sacrificing the specific energy density compared with pristine NCM622. The optimal NCM622/LVP-C composite presents a high specific capacity of 162 mA h g at 0.5 C and excellent cycling performance with 85.0% capacity retention after 200 cycles at 2 C, higher than that of the pristine NCM622 (67.6%). Systematic characterization confirms that the LVP-C protective layer can effectively reduce the side reactions, restrict the cation mixing of NCM622 and improve its structural stability. Moreover, the NCM622/LVP-C||graphite full cells also show a commercial-level capacity of 3.2 mA h cm and much improved cycling stability compared with NCM622/LVP-C||graphite full cells, indicating the great promise for low-cost, high-capacity and long-life LIBs.
富镍层状氧化物，如LiNiCoMnO（NCM622），是下一代高能量锂离子电池（LIBs）最有前景的候选材料之一。然而，原始的富镍正极材料在循环过程中通常结构稳定性较差。在这项工作中，我们展示了一种简单而有效的方法，通过干涂超稳定的LiV(PO)-碳（LVP-C）纳米颗粒来提高NCM622正极的循环稳定性，从而得到一种坚固的复合正极（NCM622/LVP-C），与原始的NCM622相比，其比能量密度没有损失。最佳的NCM622/LVP-C复合材料在0.5 C下具有162 mA h g的高比容量，在2 C下循环200次后容量保持率为85.0%，循环性能优异，高于原始NCM622（67.6%）。系统表征证实，LVP-C保护层可以有效减少副反应，限制NCM622的阳离子混合并提高其结构稳定性。此外，NCM622/LVP-C||石墨全电池也显示出3.2 mA h cm的商业级容量，与NCM622/石墨全电池相比，循环稳定性有了很大提高，这表明低成本、高容量和长寿命LIBs具有很大的前景。
