Li3VP3O9N as a Multielectron Redox Cathode for Li-Ion Battery,Chemistry of Materials

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Li3VP3O9N as a Multielectron Redox Cathode for Li-Ion Battery
Chemistry of Materials ( IF 7.2 ) Pub Date : 2018-05-23 00:00:00 , DOI: 10.1021/acs.chemmater.8b01114
Jue Liu _{1,

2} , Liang Yin ₁ , Xiao-Qing Yang ₂ , Peter G. Khalifah _{1,

2}

Affiliation

Li₃VP₃O₉N was for the first time synthesized from its sodium analogue Na₃VP₃O₉N using a solid–solid Li⁺/Na⁺ ion-exchange method. This lithium variant of nitridophosphate is found to possess similar crystal structure (space group P2₁3) as its sodium analogue Na₃VP₃O₉N (a = 9.4507(1) Å) but with much smaller lattice parameter (a = 9.1237(1) Å). The crystal structure of Li₃VP₃O₉N was solved and refined using combined synchrotron X-ray and time-of-flight neutron powder diffraction data, allowing the three distinct lithium-ion sites to be identified. A lithium bond valence sum difference map calculation suggests the existence of isotropic three-dimensional lithium-ion-conducting pathways with a minimum valence threshold |ΔV| of 0.02. Li₃VP₃O₉N behaves as a promising reversible cathode material for rechargeable lithium-ion batteries with an average V³⁺/V⁴⁺ redox potential of 3.8 V (vs Li⁺/Li). Both cyclic voltammetry tests and chemical delithiation (using NO₂BF₄) indicate it is possible to partially remove the second lithium from the structure, though only at very high potentials (>4.9 V vs Li⁺/Li). It is also found that the unit cell volume of this compound expands instead of shrinking upon lithium removal, a rare phenomenon for polyanion-based cathodes. This abnormal volume expansion is found to be associated with the drastic expansion of the Li1(O1)₃N tetrahedral site after removing lithium from this site.

中文翻译：

Li ₃ VP ₃ O ₉ N作为锂离子电池的多电子氧化还原阴极

Li ₃ VP ₃ O ₉ N首次使用固体-固体Li ⁺ / Na ⁺离子交换法从其钠类似物Na ₃ VP ₃ O ₉ N合成。发现该亚硝酸磷酸锂的锂变体与其钠类似物Na ₃ VP ₃ O ₉ N（a = 9.4507（1）Å）具有相似的晶体结构（空间群P 2 ₁ 3），但晶格参数小得多（a = 9.1237）（1）Å）。Li ₃ VP ₃ O ₉的晶体结构使用同步加速器X射线和飞行时间中子粉末衍射数据相结合的方法，对N进行了解析和精制，从而可以识别出三个不同的锂离子位点。锂键合价差图谱计算表明存在具有最小化合价阈值|ΔV|的各向同性三维锂离子传导途径。0.02。Li ₃ VP ₃ O ₉ N表现为可再充电锂离子电池的有希望的可逆阴极材料，其平均V ³⁺ / V ⁴⁺氧化还原电势为3.8 V（vs Li ⁺ / Li）。循环伏安法测试和化学脱锂（使用NO ₂ BF ₄）表明尽管仅在非常高的电势下（> 4.9 V vs Li ⁺ / Li）仍可能从结构中部分去除第二个锂。还发现，除去锂后，该化合物的晶胞体积膨胀而不是收缩，这对于基于聚阴离子的阴极是罕见的现象。发现这种异常的体积膨胀与从该位置除去锂后Li1（O1）₃ N四面体位置的急剧膨胀有关。

更新日期：2018-05-23

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