Local Electronic Structure Modulation Enables Fast-Charging Capability for Li-Rich Mn-Based Oxides Cathodes With Reversible Anionic Redox Activity,Advanced Functional Materials

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Local Electronic Structure Modulation Enables Fast-Charging Capability for Li-Rich Mn-Based Oxides Cathodes With Reversible Anionic Redox Activity
Advanced Functional Materials ( IF 18.5 ) Pub Date : 2023-06-21 , DOI: 10.1002/adfm.202304065
Xianggang Gao ₁ , Haiyan Zhang _{1,

2} , Shihao Li ₁ , Shuai Zhang ₁ , Chaohong Guan ₃ , Xiaoping Hu ₄ , Juanlang Guo ₁ , Yanqing Lai ₁ , Zhian Zhang ₁

Affiliation

Anionic and cationic redox chemistries boost ultrahigh specific capacities of Li-rich Mn-based oxides cathodes (LRMO). However, irreversible oxygen evolution and sluggish kinetics result in continuous capacity decay and poor rate performance, restricting the commercial fast-charging cathodes application for lithium ion batteries. Herein, the local electronic structure of LRMO is appropriately modulated to alleviate oxygen release, enhance anionic redox reversibility, and facilitate Li⁺ diffusion via facile surface defect engineering. Concretely, oxygen vacancies integrated on the surface of LRMO reduce the density of states of O 2p band and trigger much delocalized electrons to distribute around the transition metal, resulting in less oxygen release, enhancing reversible anionic redox and the MnO₆ octahedral distortion. Besides, partially reduced Mn and lattice vacancies synchronously stimulate the electrochemical activity and boost the electronic conductivity, Li⁺ diffusion rate, and fast charge transfer. Therefore, the modified LRMO exhibits enhanced cyclic stability and fast-charging capability: a high discharging capacity of 212.6 mAh·g⁻¹ with 86.98% capacity retention after 100 cycles at 1 C is obtained and to charge to its 80%, SOC is shortened to 9.4 min at 5 C charging rate. This work will draw attention to boosting the fast-charging capability of LRMO via the local electronic structure modulation.

中文翻译：

局部电子结构调制使具有可逆阴离子氧化还原活性的富锂锰基氧化物阴极具有快速充电能力

阴离子和阳离子氧化还原化学物质提高了富锂锰基氧化物阴极（LRMO）的超高比容量。然而，不可逆的析氧和缓慢的动力学导致持续的容量衰减和较差的倍率性能，限制了锂离子电池快速充电正极的商业应用。在此，LRMO的局域电子结构被适当调节，以减轻氧释放，增强阴离子氧化还原可逆性，并通过简单的表面缺陷工程促进Li ⁺扩散。具体而言，LRMO表面集成的氧空位降低了O 2p能带的态密度，并引发大量离域电子分布在过渡金属周围，导致氧释放减少，增强了可逆阴离子氧化还原和MnO 6 八面体_畸变。此外，部分减少的Mn和晶格空位同步刺激电化学活性并提高电子电导率、Li ⁺扩散速率和快速电荷转移。因此，改进的LRMO表现出增强的循环稳定性和快速充电能力：在1 C下100次循环后获得212.6 mAh·g ^-1的高放电容量，容量保持率为86.98%，充电至80%时，SOC缩短在 5 C 充电速率下可达 9.4 分钟。这项工作将引起人们对通过局域电子结构调制提高 LRMO 快速充电能力的关注。

更新日期：2023-06-21

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