Kinetic Rejuvenation of Li-Rich Li-Ion Battery Cathodes upon Oxygen Redox,ACS Applied Energy Materials

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Kinetic Rejuvenation of Li-Rich Li-Ion Battery Cathodes upon Oxygen Redox
ACS Applied Energy Materials ( IF 5.4 ) Pub Date : 2020-07-24 00:00:00 , DOI: 10.1021/acsaem.0c01315
Jinhyuk Lee ₁ , Daiwei Yu ₂ , Zhi Zhu ₁ , Xiahui Yao ₁ , Chao Wang ₁ , Yanhao Dong ₁ , Rahul Malik ₃ , Ju Li _{1,

4}

Affiliation

Minimizing internal structural rearrangements upon oxygen redox is currently considered the chief guideline for designing high-performance Li-rich cathodes for Li-ion batteries. In contrast, our study of Li-rich layered- and disordered-rocksalt cathodes reveals that while global oxygen mobility promoted upon O-redox can be damaging, disruption of a local structural order [e.g., medium-range-order (MRO)] triggered by O-redox and associated volume expansion are highly beneficial as they reduce the Li-transport resistance in the materials, that is, the Li-rich cathodes become “rejuvenated” by this process. Furthermore, we use this knowledge to inform a molten-salt treatment to predisturb the MRO, expand crystal volume before cycling, and endow a surface gradient composition for highly Li-rich Co-free layered cathodes, such that the treated materials can achieve high capacity (>230 mA h/g) from the very first cycle with excellent rate capability (154 mA h/g at 2 A/g) and outstanding capacity/voltage-retention (∼4% capacity-loss, ∼140 mV voltage-loss after 200 cycles at 100 mA/g; >210 mA h/g). From these results, we explain the mechanism and universality of the rejuvenation process in various charge-ordered oxides and propose guidelines for designing advanced Li-rich cathode materials with combined transition-metal- and oxygen-redox activities.

中文翻译：

富氧锂离子电池在氧氧化还原作用下的动力学活化

目前，将氧还原还原时的内部结构重排降至最低被认为是设计用于锂离子电池的高性能富锂阴极的主要指南。相比之下，我们对富锂的层状和无序岩盐阴极的研究表明，尽管O-氧化还原所促进的整体氧迁移率可能会造成破坏，但会破坏局部结构秩序[例如，由O-氧化还原引发的中程（MRO）和相关的体积膨胀非常有益，因为它们可以降低材料中的Li传输阻力，也就是说，富Li的阴极通过此过程“恢复了活力”。此外，我们利用这些知识来进行熔盐处理，以预扰动MRO，在循环之前扩大晶体体积，并为高度富锂的无钴层状阴极提供表面梯度成分，从而使处理后的材料能够实现高容量从最初的周期开始（> 230 mA h / g），具有出色的倍率能力（在2 A / g时为154 mA h / g）和出色的容量/电压保持率（〜4％容量损失，〜140 mV电压损失）在100 mA / g;> 210 mA h / g的200个循环后）。根据这些结果，

更新日期：2020-07-24

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