High-Coulombic-Efficiency Carbon/Li Clusters Composite Anode without Precycling or Prelithiation.
High-Coulombic-Efficiency Carbon/Li Clusters Composite Anode without Precycling or Prelithiation.
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DOI：
10.1002/smll.201802226
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发表时间：
2018-07
期刊：
影响因子：
13.3
通讯作者：
R. Tian;H. Duan;Yiping Guo;Hua Li;Hezhou Liu
中科院分区：
文献类型：
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作者：
R. Tian;H. Duan;Yiping Guo;Hua Li;Hezhou Liu
近年来，金属锂作为高能量密度锂离子电池的负极材料引起了人们极大的研究兴趣。然而，其实际应用受到无法控制的沉积、体积膨胀和枝晶形成的严重限制。这里，当发现过锂碳布(CC)时，在LiC6和Li树枝晶之间形成了Li，Li团簇的亚稳态。尺寸在微米和亚微米级的Li团簇具有优异的Li+和Li之间的电化学可逆性，使得CC/Li团簇复合负极表现出高的首次循环库仑效率(CE)94.5%±1.0%和160次循环的稳定CE(99.9%)，这在碳/锂复合负极中是例外的。CC/Li团簇复合负极具有较高的容量(3mAhcm-2)，这是由Li+插层和Li团簇形成共同贡献的，具有良好的循环稳定性和特征的斜率电压分布。此外，CC/Li团簇复合负极无需预循环或预锂化即可组装成全电池。以裸CC为阳极，过量LiCoO2为阴极的全电池在200次循环中表现出高的比容量和良好的循环稳定性，突出了Li团簇的可控形成的优势。
Lithium metal has attracted much research interest as a possible anode material for high-energy-density lithium-ion batteries in recent years. However, its practical use is severely limited by uncontrollable deposition, volume expansion, and dendrite formation. Here, a metastable state of Li, Li cluster, that forms between LiC6 and Li dendrites when over-lithiating carbon cloth (CC) is discovered. The Li clusters with sizes in the micrometer and submicrometer scale own outstanding electrochemical reversibility between Li+ and Li, allowing the CC/Li clusters composite anode to demonstrate a high first-cycle coulombic efficiency (CE) of 94.5% ± 1.0% and a stable CE of 99.9% for 160 cycles, which is exceptional for a carbon/lithium composite anode. The CC/Li clusters composite anode shows a high capacity of 3 mAh cm-2 contributed by both Li+ intercalation and Li-cluster formation, and excellent cycling stability with a signature sloping voltage profile. Furthermore, the CC/Li clusters composite anode can be assembled into full cells without precycling or prelithiation. The full cells containing bare CC as the anode and excessive LiCoO2 as the cathode exhibit high specific capacity and good cyclic stability in 200 cycles, stressing the advantage of controlled formation of Li clusters.