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Gradient-morph LiCoO2 single crystals with stabilized energy density above 3400 W h L−1
Energy & Environmental Science ( IF 32.4 ) Pub Date : 2020-05-20 , DOI: 10.1039/d0ee00231c Zhi Zhu 1, 2, 3, 4, 5 , Daiwei Yu 1, 2, 3, 4, 5 , Zhe Shi 1, 2, 3, 4, 5 , Rui Gao 1, 2, 3, 4, 5 , Xianghui Xiao 5, 6, 7, 8 , Iradwikanari Waluyo 5, 6, 7, 8 , Mingyuan Ge 5, 6, 7, 8 , Yanhao Dong 1, 2, 3, 4, 5 , Weijiang Xue 1, 2, 3, 4, 5 , Guiyin Xu 1, 2, 3, 4, 5 , Wah-Keat Lee 5, 6, 7, 8 , Adrian Hunt 5, 6, 7, 8 , Ju Li 1, 2, 3, 4, 5
Energy & Environmental Science ( IF 32.4 ) Pub Date : 2020-05-20 , DOI: 10.1039/d0ee00231c Zhi Zhu 1, 2, 3, 4, 5 , Daiwei Yu 1, 2, 3, 4, 5 , Zhe Shi 1, 2, 3, 4, 5 , Rui Gao 1, 2, 3, 4, 5 , Xianghui Xiao 5, 6, 7, 8 , Iradwikanari Waluyo 5, 6, 7, 8 , Mingyuan Ge 5, 6, 7, 8 , Yanhao Dong 1, 2, 3, 4, 5 , Weijiang Xue 1, 2, 3, 4, 5 , Guiyin Xu 1, 2, 3, 4, 5 , Wah-Keat Lee 5, 6, 7, 8 , Adrian Hunt 5, 6, 7, 8 , Ju Li 1, 2, 3, 4, 5
Affiliation
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The cycling stability of LiCoO2 under high voltages (>4.5 V) was plagued by hybrid anion- and cation-redox (HACR) induced oxygen escape and uncontrolled phase collapse. With DEMS and in situ XANES mapping at the NSLS-II, we demonstrate that oxygen escape triggers irreversible transformations into “bad” surface phases that rapidly propagate inward. Enabling HACR but stopping global oxygen migration is key to a stable high-energy cathode. Therefore, we developed ∼10 μm single crystals with LiCoO2 in the bulk smoothly transitioning to Co-free LiMn0.75Ni0.25O2 at the surface. By means of initial electrochemical formation, a semi-coherent LiMn1.5Ni0.5O4 spinel-like shell was established in operando with little oxygen loss to integrally wrap the LiCoO2 bulk. Then we obtained gradient-morph LiCoO2 single crystals to prevent the percolating migration of oxygen out of the particle and achieved enhanced HACR reversibility at high voltages. The gradient-morph HACR cathode undergoes substantially stabilized cycling when charged to above 4.6 V, and hence a stable cyclic volumetric energy density of >3400 W h L−1 has been achieved in a pouch full-cell coupled with a commercial graphite anode and lean electrolyte (2 g A h−1), exhibiting up to 2906 W h L−1 even after 300 cycles.
中文翻译：
能量密度稳定在3400 W h L-1以上的梯度变LiCoO2单晶
LiCoO 2在高电压（> 4.5 V）下的循环稳定性受到混合的阴离子和阳离子氧化还原（HACR）诱导的氧气逸出和失控相塌陷的困扰。通过在NSLS-II上进行DEMS和原位XANES映射，我们证明了氧气逸出触发了不可逆转的转变为迅速向内传播的“坏”表面相。启用HACR但阻止全局氧气迁移是稳定高能阴极的关键。因此，我们开发了约10μm的单晶，其中的LiCoO 2在表面顺利过渡为无Co的LiMn 0.75 Ni 0.25 O 2。通过初始电化学形成，形成了半相干的LiMn 1.5 Ni在操作中建立了几乎没有氧气损失的0.5 O 4尖晶石状壳，以整体包裹LiCoO 2。然后，我们获得了梯度形貌的LiCoO 2单晶，以防止氧气从颗粒中渗出，并在高压下实现了增强的HACR可逆性。梯度晶型HACR阴极在充电至4.6 V以上时会经历基本稳定的循环，因此，在装有市售石墨阳极和贫油的袋装全电池中，已实现了大于3400 W h L -1的稳定循环体积能量密度电解质（2 g A h -1），即使经过300次循环也显示高达2906 W h L -1。
更新日期：2020-06-19
中文翻译：
能量密度稳定在3400 W h L-1以上的梯度变LiCoO2单晶
LiCoO 2在高电压（> 4.5 V）下的循环稳定性受到混合的阴离子和阳离子氧化还原（HACR）诱导的氧气逸出和失控相塌陷的困扰。通过在NSLS-II上进行DEMS和原位XANES映射，我们证明了氧气逸出触发了不可逆转的转变为迅速向内传播的“坏”表面相。启用HACR但阻止全局氧气迁移是稳定高能阴极的关键。因此，我们开发了约10μm的单晶，其中的LiCoO 2在表面顺利过渡为无Co的LiMn 0.75 Ni 0.25 O 2。通过初始电化学形成，形成了半相干的LiMn 1.5 Ni在操作中建立了几乎没有氧气损失的0.5 O 4尖晶石状壳，以整体包裹LiCoO 2。然后，我们获得了梯度形貌的LiCoO 2单晶，以防止氧气从颗粒中渗出，并在高压下实现了增强的HACR可逆性。梯度晶型HACR阴极在充电至4.6 V以上时会经历基本稳定的循环，因此，在装有市售石墨阳极和贫油的袋装全电池中，已实现了大于3400 W h L -1的稳定循环体积能量密度电解质（2 g A h -1），即使经过300次循环也显示高达2906 W h L -1。
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