Manipulating the Local Electronic Structure in Li-Rich Layered Cathode Towards Superior Electrochemical Performance,Advanced Functional Materials

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Manipulating the Local Electronic Structure in Li-Rich Layered Cathode Towards Superior Electrochemical Performance
Advanced Functional Materials ( IF 18.5 ) Pub Date : 2021-05-16 , DOI: 10.1002/adfm.202100783
Hongfei Zheng ₁ , Chenying Zhang ₁ , Yinggan Zhang ₁ , Liang Lin ₁ , Pengfei Liu ₂ , Laisen Wang ₁ , Qiulong Wei ₁ , Jie Lin ₁ , Baisheng Sa ₃ , Qingshui Xie ₁ , Dong‐Liang Peng ₁

Affiliation

Manipulating the local electronic structure is employed to address the capacity/voltage decay and poor rate capability of Li-rich layered cathodes (LLOs) via the dual-doping of Na⁺ and F⁻ ions, as well as the regulation of Li⁺/Ni²⁺ intermixing and the content of “LiOLi” configuration. The designed cathode exhibits a high initial Coulombic efficiency of about 90%, large specific capacity of 296 mAh g⁻¹ and energy density of 1047 Wh kg⁻¹ at 0.2 C, and a superior rate capability of 222 mAh g⁻¹ at 5 C with a good capacity retention of 85.7% even after 500 cycles. And the operating voltage is increased without compromising the high-capacity advantage. Such improved electrochemical performances primarily result from the band shift of the TM 3d-O 2p and non-bonding O-2p to lower energy, which would decrease Li⁺ diffusion activation energy and increase oxygen vacancy forming energy, finally improving the Li⁺ diffusion kinetics and stabilizing lattice oxygen. Moreover, the increased “LiOLi” configuration in the Li₂MnO₃ phase via increasing the Mn concentration can increase the reversible capacity to offset the negative effect of inactive doping and Li⁺/Ni²⁺ intermixing. This strategy of modulating the local electronic structure of LLOs provides great potential to design high-energy-density Li-ion batteries.

中文翻译：

操纵富锂层状阴极中的局部电子结构以获得优异的电化学性能

操纵局部电子结构用于通过 Na ⁺和 F ^-离子的双重掺杂以及 Li ⁺ /Ni的调节来解决富锂层状正极 (LLO) 的容量/电压衰减和较差的倍率性能²⁺混杂和“李的内容 Ò 李”的配置。所设计的正极具有约 90% 的高初始库仑效率、296 mAh g ^{-1 的}大比容量和 1047 Wh kg ^-1在 0.2 C 下的能量密度以及 222 mAh g ^-1的优异倍率性能在 5 C 下，即使在 500 次循环后仍具有 85.7% 的良好容量保持率。并且在不影响高容量优势的情况下提高了工作电压。这种改善的电化学性能主要是由于 TM 3d-O 2p 和非键合 O-2p 的带移降低能量，这将降低 Li ⁺扩散活化能并增加氧空位形成能，最终改善 Li ⁺扩散动力学和稳定晶格氧。此外，通过增加Mn浓度在Li ₂ MnO ₃相中增加的“Li  O  Li”构型可以增加可逆容量以抵消非活性掺杂和Li ⁺的负面影响。/Ni ²⁺混合。这种调节 LLO 局部电子结构的策略为设计高能量密度锂离子电池提供了巨大的潜力。

更新日期：2021-07-22

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