Dendrite‐Free Li‐Metal Anode Enabled by Dendritic Structure
Dendrite‐Free Li‐Metal Anode Enabled by Dendritic Structure
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DOI：
10.1002/adfm.202009712
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发表时间：
2021-02
影响因子：
19
通讯作者：
Hongyu Zhang;Shunlong Ju;Guanglin Xia;Dalin Sun;Xuebin Yu
中科院分区：
文献类型：
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作者：
Hongyu Zhang;Shunlong Ju;Guanglin Xia;Dalin Sun;Xuebin Yu
锂金属阳极在高能可充电锂电池中的实际应用仍然受到锂枝晶形成不可控的阻碍。在这里，报道了一种通过构建富含含锂聚合物作为物理保护层和LiH作为锂离子导体的树枝状Li 3 Mg 7合金来稳定锂金属阳极的简便方法。这种独特的树枝状结构有效地降低了局部电流密度，并在重复的Li电镀/剥离过程中适应体积变化。更重要的是，亲锂Li 3 Mg 7合金不仅在Li沉积时将Li均匀沉积向下引导到下方的Li金属中，而且在反向Li剥离过程中促进Li的提取，这抑制了Li金属表面上发生的寄生反应，从而抑制了Li枝晶的形成。此外，在热力学上允许Mg从Li 3 Mg 7合金向下方的Li金属的容易扩散，这导致LiMg合金在整个电极内均匀分布，从而有利于长期深循环稳定性。因此，受保护的锂金属阳极在10 mA h cm−2下可提供稳定且无枝晶的循环性能，持续时间超过900 h。当将该阳极与LiFePO 4和S阴极耦合时，由此组装的全电池表现出上级循环稳定性。
The practical application of Li‐metal anode in high‐energy rechargeable Li batteries is still hindered by the uncontrollable formation of Li dendrites. Here, a facile way is reported to stabilize Li‐metal anode by building dendrite‐like Li3Mg7 alloys enriched with Li‐containing polymers as the physical protecting layer and LiH as the Li‐ion conductor. This unique dendritic structure effectively reduces local current density and accommodates volume change during the repeated Li plating/stripping process. More importantly, lithiophilic Li3Mg7 alloys not only guide the uniform Li deposition down into the below Li metal upon Li deposition, but also thermodynamically promote the extraction of Li during the reverse Li stripping process, which suppresses the parasitic reactions occurring on the surface of Li metal and hence inhibits the formation of Li dendrites. Moreover, the facile diffusion of Mg from Li3Mg7 alloys toward Li metal below is thermodynamically permitted, which leads to a uniform distribution of LiMg alloys inside the whole electrode and thus benefits long‐term deep cycling stability. As a result, the protected Li‐metal anode delivers stable and dendrite‐free cycling performance at 10 mA h cm−2 for over 900 h. When coupling this anode with LiFePO4 and S cathodes, the thus‐assembled full cells exhibit superior cycling stability.