Suppressing Li dendrite by a protective biopolymeric film from tamarind seed polysaccharide for high-performance Li metal anode
Suppressing Li dendrite by a protective biopolymeric film from tamarind seed polysaccharide for high-performance Li metal anode
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通过罗望子种子多糖的保护性生物聚合物膜抑制锂枝晶，用于高性能锂金属负极
DOI：
10.1016/j.electacta.2019.01.045
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发表时间：
2019
影响因子：
6.6
通讯作者：
Sun Shi Gang
中科院分区：
文献类型：
--
作者：
You Jin Hai;Zhang Shao Jian;Deng Li;Li Meng Zhu;Zheng Xiao Mei;Li Jun Tao;Zhou Yao;Huang Ling;Sun Shi Gang
锂金属是锂基电池的一种有前途的阳极，但仍然存在锂枝晶生成和界面不稳定性的问题。本文首次将罗望子多糖（TSP）作为一种具有高骨架取代度、高粘度、高硬度、高弹性和在有机电解质中的稳定性的天然高分子材料用于锂金属阳极保护。使用这种生物聚合物，具有最佳厚度的均匀TSP保护膜容易地涂覆在Cu箔上（TSP-Cu），这可以有利于Li金属在Cu箔上的均匀电沉积，并且成功地抑制了在长时间循环期间枝晶的形成。如此涂覆的Li@TSP-Cu阳极即使在5 mA cm-2的高电流密度下也可以提供超过90次循环的稳定循环性能，具有低过电位，总容量为2 mAh cm-2，而裸阳极，即，Li@Cu在初始循环中变得不稳定。此外，即使在1 mA cm-2的电流密度和1 mAh cm-2的容量下循环超过100次之后，涂覆的电极也可以保持98.5%的库仑效率，上级裸Cu电极，裸Cu电极在相同条件下在不到50次循环内下降到40%以下。电化学阻抗分析，SEM和XPS表征的循环阳极进一步证实了TSP保护层的作用，在阻止重复再生的SEI层和稳定的电极界面。我们的工作展示了生物聚合物保护膜在高能量密度可充电锂金属电池中构建稳定且无枝晶的锂金属阳极的前景。
Li metal, which is a promising anode for Li based batteries, still suffers from the Li dendritic generation and interfacial instability. Herein, for the first time, tamarind seed polysaccharide (TSP), a natural polymer with ultrahigh degree of backbone substitution, high viscosity and hardness, excellent elasticity and remarkable stability in organic electrolytes, was employed for Li metal anode protection. Using such biopolymer, an even TSP protective film with optimal thickness was facile coated on the Cu foil (TSP-Cu), which could favor the homogeneous electrodeposition of Li metal on the Cu foil and successfully inhibits the formation of dendrite during prolonged cycles. Thus-coated Li@TSP-Cu anode can deliver a stable cycling performance for more than 90 cycles with a low over-potential even at a high current density of 5 mA cm−2with a total capacity of 2 mAh cm−2, whereas the bare anode, i.e., Li@Cu, becomes unstable in initial cycle. Furthermore, the coated electrode could maintain a coulomb efficiency of 98.5% even after cycling for more than 100 cycles under a current density of 1 mA cm−2with capacity of 1 mAh cm−2, superior to the bare Cu electrode which drops below 40% within less than 50 cycles under the same conditions. Electrochemical impedance analysis, SEM and XPS characterizations of the cycled anodes further confirmed the role of the TSP protective layer in blocking the repetitive regeneration of the SEI layer and in stabilizing the electrode interface. Our work demonstrated the promising perspective of biopolymeric protective films for construction of stable and dendrite-free Li metal anode in high-energy-density rechargeable Li metal batteries.