Deciphering the Origin of High Electrochemical Performance in a Novel Ti-Substituted P2/O3 Biphasic Cathode for Sodium-Ion Batteries
Deciphering the Origin of High Electrochemical Performance in a Novel Ti-Substituted P2/O3 Biphasic Cathode for Sodium-Ion Batteries
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解读钠离子电池新型钛取代 P2/O3 双相阴极高电化学性能的起源
DOI：
10.1021/acsami.0c11427
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发表时间：
2020
影响因子：
9.5
通讯作者：
Hu Bingwen
中科院分区：
文献类型：
--
作者：
Hu Bei;Geng Fushan;Zhao Chong;Doumert Bertr;Trebosc Julien;Lafon Olivier;Li Chao;Shen Ming;Hu Bingwen
层状锰基氧化物（NaxMnO2）因其可调的电化学性能和低廉的成本而受到广泛关注，是最有前途的可充电钠离子电池阴极家族之一。本文报道了一种新型的P2/O3互生含锂的na0.8 li0.27 mn0.68 ti0.05 o2正极材料。得益于两相复合结构和无活性元素取代的协同效应，该P2/O3电极具有较高的初充放电容量和优良的循环性能。不同表征技术的结合，包括固态核磁共振、电子顺磁共振、x射线吸附光谱和高分辨率透射电子显微镜，可以深入了解当地的电子环境、氧化还原化学，以及这些阴极材料在循环时的微观结构刚性。通过与不含ti的P2/O3-Na0.8Li0.27Mn0.73O2的综合比较，发现其电化学性能的提高主要是由于减缓了臭名昭著的Mn3+/Mn4+氧化还原，增强了氧电荷补偿行为的稳定性。从结构演化的角度来看，钛取代抑制了循环过程中Li+的损失和不可逆的结构降解。本研究对非活性d0元素取代后的电子和晶体结构演变有了深入的了解，对高性能P2/O3双相锰基层状阴极的合理设计有一定的指导意义。
The layered Mn-based oxides (NaxMnO2), which is one of the most promising cathode families for rechargeable sodium-ion batteries, have received considerable attention because of their tunable electrochemical performances and low costs. Herein, a novel P2/O3 intergrown Li-containing Na0.8Li0.27Mn0.68Ti0.05O2cathode material prepared by Ti-substitution into Mn-site is reported. Benefiting from the synergistic effects of the biphasic composite structure and inactive d0element substitution, this P2/O3 electrode exhibits high initial charge/discharge capacity and excellent cycling performance. The combination of different characterization techniques including solid-state NMR, electron paramagnetic resonance, X-ray adsorption spectroscopy, and high-resolution transmission electron microscopy gives insights into the local electronic environment, the redox chemistry, and also the microstructure rigidity of these cathode materials upon cycling. On the basis of comprehensive comparison with the Ti-free P2/O3-Na0.8Li0.27Mn0.73O2, the observed improvement on the electrochemical performance is primarily attributed to the mitigation of notorious Mn3+/Mn4+redox and the enhanced stability of the oxygen charge compensation behavior. From the viewpoint of structure evolution, Ti-substitution restrains the Li+loss and irreversible structural degradation during cycling. This study provides an in-depth understanding of the electronic and crystal structure evolutions after inactive d0element substitution and may shed light on the rational design of high-performance P2/O3 biphasic Mn-based layered cathodes.