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Manipulating External Electric Field and Tensile Strain toward High Energy Density Stability in Fast-Charging Li-Rich Cathode Materials
The Journal of Physical Chemistry Letters ( IF 4.8 ) Pub Date : 2020-03-09 , DOI: 10.1021/acs.jpclett.9b03871
Pengfei Liu 1 , Wei He 1 , Yong Cheng 1 , Qian Wang 1 , Chenying Zhang 1 , Qingshui Xie 1 , Jiangtao Han 1 , Zhensong Qiao 1 , Hongfei Zheng 1 , Qun Liu 1 , Laisen Wang 1 , Baihua Qu 2 , Qing Luo 1 , Zi-Zhong Zhu 3 , Dong-Liang Peng 1
Affiliation  

Li-rich layered oxides (LLOs) are promising cathodes for lithium-ion batteries because of their high energy density provided by anionic redox. Although great improvements have been achieved in electrochemical performance, little attention has been paid to the energy density stability during fast charging. Indeed, LLOs have severe capacity fading and voltage decay especially at a high state of charge (SOC), disabling the application of the frequently used constant-current–constant-voltage mode for fast charging. Herein, we address this problem by manipulating the external electric field and tensile strain induced by lattice expansion effect in nanomaterials under the guidance of theoretical calculations, which indicate that LLOs at high SOC have almost a zero band gap and a low oxygen formation energy. This strategy will weaken polarization, stabilize lattice oxygen, and restrict phase transition simultaneously. Thus, the energy density during fast charging can be highly stabilized. Therefore, it may be of great value for the practical application of layered cathodes.

中文翻译:

快速充电富锂阴极材料中的外部电场和拉伸应变朝高能量密度稳定性的方向进行。

富含锂的层状氧化物(LLO)是锂离子电池理想的阴极,因为它们由阴离子氧化还原提供高能量密度。尽管在电化学性能上已经取得了很大的进步,但是在快速充电过程中很少关注能量密度的稳定性。实际上,LLO具有严重的容量衰减和电压衰减现象,尤其是在高充电状态(SOC)时,无法将常用的恒流-恒压模式用于快速充电。在这里,我们通过在理论计算的指导下操纵纳米材料中由晶格膨胀效应引起的外部电场和拉伸应变来解决此问题,这表明在高SOC下的LLO几乎具有零带隙和低氧形成能。这种策略将削弱两极分化,稳定晶格氧,并同时限制相变。因此,可以高度稳定快速充电期间的能量密度。因此,对于层状阴极的实际应用可能具有很大的价值。
更新日期:2020-03-10
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