新型Na3.9MnCr0.9Zr0.1(PO4)3正极的高能量密度和长循环寿命的“双赢”场景,Energy & Environmental Materials

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新型Na3.9MnCr0.9Zr0.1(PO4)3正极的高能量密度和长循环寿命的“双赢”场景
Energy & Environmental Materials ( IF 13.0 ) Pub Date : 2022-09-10 , DOI: 10.1002/eem2.12519
Yao Wang ₁ , Yukun Liu ₁ , Pingge He ₂ , Junteng Jin ₁ , Xudong Zhao ₃ , Qiuyu Shen ₁ , Jie Li ₁ , Xuanhui Qu ₁ , Yongchang Liu _{1,

4} , Lifang Jiao ₄

Affiliation

高比能、长寿命的NASICON型钠离子电池正极材料的开发一直是研究热点，也是一项艰巨的挑战。尽管Na ₄ MnCr(PO ₄ ) ₃由于其三电子反应而成为最有前途的高能量密度正极材料之一，但它在重复充电/放电过程中仍然遭受着由Jahn-引起的严重的结构变形。柜员活性锰³⁺。_{本文探索了Na 4} MnCr(PO ₄ ) ₃中Zr选择性取代Cr以增强结构稳定性，由于Zr离子的钉扎效应和≈2.9电子反应，制备了Na _3.9 MnCr _0.9 Zr _0.1 (PO ₄ ) ₃ /C在5 C下500次循环后具有85.94%的高容量保持率，在0.1 C下具有156.4 mAh g ^-1的超高容量，使稳定的能量输出高达555.2 Wh kg ^-1。此外，在整个充放电过程中，通过原位X射线衍射验证了仅6.7%的微小体积变化，以及Cr ³⁺ /Cr ⁴⁺、Mn 3+ /Mn 4+ 和Mn ³⁺ /Mn ⁴⁺的可逆反应。通过非原位X射线光电子能谱分析鉴定了Mn ²⁺ /Mn ^{3+氧化还原对。}恒电流间歇滴定技术测试和密度泛函理论计算进一步证明了Na _3.9 MnCr _0.9 Zr _0.1 (PO ₄ ) ₃ /C电极的快速反应动力学。这项工作为通过离子掺杂设计高能、高稳定性 NASICON 阴极提供了新的机会。

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“Win-Win” Scenario of High Energy Density and Long Cycling Life in a Novel Na3.9MnCr0.9Zr0.1(PO4)3 Cathode

The development of high-energy and long-lifespan NASICON-type cathode materials for sodium-ion batteries has always been a research hotspot but a daunting challenge. Although Na₄MnCr(PO₄)₃ has emerged as one of the most promising high-energy-density cathode materials owing to its three-electron reactions, it still suffers from serious structural distortion upon repetitive charge/discharge processes caused by the Jahn-Teller active Mn³⁺. Herein, the selective substitution of Cr by Zr in Na₄MnCr(PO₄)₃ was explored to enhance the structural stability, due to the pinning effect of Zr ions and the ≈2.9-electron reactions, as-prepared Na_3.9MnCr_0.9Zr_0.1(PO₄)₃/C delivers a high capacity retention of 85.94% over 500 cycles at 5 C and an ultrahigh capacity of 156.4 mAh g⁻¹ at 0.1 C, enabling the stable energy output as high as 555.2 Wh kg⁻¹. Moreover, during the whole charge/discharge process, a small volume change of only 6.7% was verified by in situ X-ray diffraction, and the reversible reactions of Cr³⁺/Cr⁴⁺, Mn³⁺/Mn⁴⁺, and Mn²⁺/Mn³⁺ redox couples were identified via ex situ X-ray photoelectron spectroscopy analyses. Galvanostatic intermittent titration technique tests and density functional theory calculations further demonstrated the fast reaction kinetics of the Na_3.9MnCr_0.9Zr_0.1(PO₄)₃/C electrode. This work offers new opportunities for designing high-energy and high-stability NASICON cathodes by ion doping.

更新日期：2022-09-10

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