K+-Doped Li1.2Mn0.54Co0.13Ni0.13O2: A Novel Cathode Material with an Enhanced Cycling Stability for Lithium-Ion Batteries
K+-Doped Li1.2Mn0.54Co0.13Ni0.13O2: A Novel Cathode Material with an Enhanced Cycling Stability for Lithium-Ion Batteries
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DOI：
10.1021/am5017649
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发表时间：
2014-07-09
影响因子：
9.5
通讯作者：
Li, Liping
中科院分区：
文献类型：
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作者：
Li, Qi;Li, Guangshe;Li, Liping
富锂层状氧化物作为锂离子电池正极材料的应用前景备受关注，但其循环稳定性较差，在循环过程中电压衰减快。如何消除有害的脊柱生长在这方面是极具挑战性的。本文以含钾的α - mno2为原料，成功制备了原位K+掺杂Li1.20Mn0.54Co0.13Ni0.13O2。系统的研究首次证明了原位钾掺杂通过阻止循环过程中尖晶石结构的形成来稳定寄主层状结构。这可能是由于锂层中的钾离子会削弱锂层中三空位的形成和Mn的迁移形成spine！钾离子半径大可能加重尖晶石生长的位阻。因此，即使在110次循环后，获得的氧化物也表现出优异的循环稳定性，其初始容量为85% （315 mA h g(-1)）。本研究的结果具有重要的意义，为抑制碱离子掺杂导致的层状尖晶石互生提供了重要的线索，并可能推广到其他类型的层状氧化物中，以获得优异的循环性能。
Li-rich layered oxides have attracted much attention for their potential application as cathode materials in lithium ion batteries, but still suffer from inferior cycling stability and fast voltage decay during cycling. How to eliminate the detrimental spinet growth is highly challenging in this regard. Herein, in situ K+-doped Li1.20Mn0.54Co0.13Ni0.13O2 was successfully prepared using a potassium containing alpha-MnO2 as the starting material. A systematic investigation demonstrates for the first time, that the in situ potassium doping stabilizes the host layered structure by prohibiting the formation of spinel structure during cycling. This is likely due to the fact that potassium ions in the lithium layer could weaken the formation of trivacancies in lithium layer and Mn migration to form spine! structure, and that the large ionic radius of potassium could possibly aggravate steric hindrance for spinel growth. Consequently, the obtained oxides exhibited a superior cycling stability with 85% of initial capacity (315 mA h g(-1)) even after 110 cycles. The results reported in this work are fundamentally important, which could provide a vital hint for inhibiting the undesired layered-spinel intergrowth with alkali ion doping and might be extended to other classes of layered oxides for excellent cycling performance.