Suppressing the chromium disproportionation reaction in O3-type layered cathode materials for high capacity sodium-ion batteries
Suppressing the chromium disproportionation reaction in O3-type layered cathode materials for high capacity sodium-ion batteries
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抑制高容量钠离子电池O3型层状正极材料中铬歧化反应
DOI：
10.1039/c6ta10818k
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发表时间：
2017-03-21
影响因子：
11.9
通讯作者：
Fu, Zheng-Wen
中科院分区：
文献类型：
--
作者：
Cao, Ming-Hui;Wang, Yong;Fu, Zheng-Wen
铬基层状阴极材料存在Cr 4+向Cr 3+和Cr 6+的不可逆还原反应，阻碍了Cr离子在层状阴极中的可逆多电子氧化还原，限制了其容量和可逆性。为了解决这个问题，一种新的O3型层状结构的过渡金属氧化物NaCr 1/3Fe 1/3 Mn 1/3 O2（NCFM）的阴极材料的设计和研究。在1.5 ~ 4.2 V的电压范围内，在0.05C的电流速率下获得了186 mA h g−1的高可逆容量。X射线衍射分析表明，NCFM在充电过程中存在O3 →（O3 + P3）→（P3 + O3 "）→ O3“的相变路径。X射线吸收谱、X射线光电子能谱和电子能量损失谱的测量结果揭示了NCFM在Na+脱嵌/嵌入过程中的电子结构变化。结果表明，Fe ~（3+）和Mn ~（4+）的取代能有效地抑制Cr ~（4+）向Cr ~（3+）和Cr ~（6+）的还原反应。这些结果表明，可逆的多电子氧化/还原的Cr离子在NCFM中可以实现在充电和放电过程中伴随着CrO 6八面体畸变和恢复。
Chromium-based layered cathode materials suffer from the irreversible disproportionation reaction of Cr4+ to Cr3+ and Cr6+, which hinders the reversible multi-electron redox of Cr ions in layered cathodes, and limits their capacity and reversibility. To address this problem, a novel O3-type layer-structured transition metal oxide of NaCr1/3Fe1/3Mn1/3O2 (NCFM) was designed and studied as a cathode material. A high reversible capacity of 186 mA h g−1 was achieved at a current rate of 0.05C in a voltage range of 1.5 to 4.2 V. X-ray diffraction revealed an O3 → (O3 + P3) → (P3 + O3′′) → O3′′ phase-transition pathway for NCFM during charge. X-ray absorption, X-ray photoelectron and electron energy-loss spectroscopy measurements revealed the electronic structure changes of NCFM during Na+ deintercalation/intercalation processes. It is confirmed that the disproportionation reaction of Cr4+ to Cr3+ and Cr6+ can be effectively suppressed by Fe3+ and Mn4+ substitution. These results demonstrated that the reversible multi-electron oxidation/reduction of Cr ions can be achieved in NCFM during charge and discharge accompanied by CrO6 octahedral distortion and recovery.