高性能混合相钠离子层状负极材料Na0.65Li0.13Mg0.13Ti0.74O2  

Mixed-Phase Na0.65Li0.13Mg0.13Ti0.74O2 as a High-Performance Na-Ion Battery Layered Anode

作　　者：丁飞翔 高飞 容晓晖 杨凯[1] 陆雅翔 胡勇胜 Feixiang Ding;Fei Gao;Xiaohui Rong;Kai Yang;Yaxiang Lu;Yong-Sheng Hu(State Key Laboratory of Operation and Control of Renewable Energy&Storage Systems,China Electric Power Research Institute,Beijing 100192,P.R.China;Institute of Physics,Chinese Academy of Sciences,Beijing 100190,P.R.China)

机构地区：[1]中国电力科学研究院有限公司,新能源与储能运行控制国家重点实验室,北京100192 [2]中国科学院物理研究所,北京100190

出　　处：《物理化学学报》2020年第5期107-113,共7页Acta Physico-Chimica Sinica

基　　金：国家电网公司科技项目(“低应变型钠基长寿命层状电池材料关键技术研究”,DG71-16-027)。

摘　　要：钛基层状氧化物因具有较低的成本、较好的空气稳定性和循环稳定性,以及较高的安全性等优点,被认为是一种具有潜在应用价值的室温钠离子电池负极材料。本文使用固相法首次设计并合成了一种新型P2相Na0.65Li0.13Mg0.13Ti0.74O2电极材料。通过延长烧结时间,可以制得混有正交相的样品,进一步研究发现该混合相样品具有更加优异的储钠性能。混合相样品首周可逆容量为96.3 mAh·g^−1,而纯P2相仅为85.1 mAh·g^−1;在1C倍率下循环400周的容量保持率为89.7%,高于P2相的84.4%,并且倍率性能显著提升(混合相样品56.6 mAh·g^−1/5C vs.纯P2相样品47.1 mAh·g^−1/2C)。该研究发现共生的两种结构能够提高材料的离子、电子传导,进而可以改善材料充放电过程中离子、电荷分布的均一性,从而提升材料的循环性能。该研究成果有助于拓展其他层状氧化物材料的研究思路,为提高钠离子电池的能量密度和循环性能提供了可行方法。With the development of clean and sustainable energy sources, the demand for large-scale electrochemical energy storage systems has rapidly increased over the last few years. Rechargeable Na-ion batteries(NIBs), one of the most promising energy storage technologies, have received a great deal of attention. Titanium-based P2-type layered oxides are attractive candidates for NIB anode materials, owing to their suitable redox potential, low cost, air stability and high safety. The exposed large interlayers of P2 configuration provide facile channels for Na+ insertion/extraction when employed as electrode materials for room temperature, non-aqueous NIBs. In this paper, a novel P2-type Na0.65Li0.13Mg0.13Ti0.74O2 is synthesized by a solid-state reaction method. An orthorhombic phase of Na0.9Mg0.45Ti1.55O2 is observed with the increase in calcination time. During the long calcination process, it is speculated that some lattice Na+ and Li+ of the previously formed P2 phase compound would be volatilized or extracted by O2, forming a low Na-content orthorhombic phase based on the layered host structure. In particular, when the precursor was calcined at 1273 K for 24 h, a perfect biphasic hybrid composite was synthesized. The Na storage performance of the pure P2 compound and hybrid composite were evaluated respectively in sodium half cells with voltage range of 0.2–2.5 V. The P2-type electrode can deliver a reversible capacity of 85.1 m Ah·g-1(theoretical capacity of approximately 108.5 m Ah·g-1), whereas, the sample with the orthorhombic phase shows an enhanced initial reversible capacity of 96.3 m Ah·g-1. Both of the curves are smooth with no observed plateau, indicating the good structural stability of the electrode during cycling. Thus, the hybrid composite exhibits better cycling performance(capacity retention of 89.7% vs. 84.4% for pure P2, after 400 cycles at current density of 1 C) and better rate capability(56.6 m Ah·g-1 at 5 C vs 47.1 m Ah·g-1 at 2 C). These results can be attributed to the introduced seco

关 键 词：钠离子电池 P2层状结构 负极材料 第二相 高可逆容量 

分 类 号：O646[理学—物理化学]