National and Local United Engineering Laboratory for Power Batteries and Department of Chemistry, Northeast Normal University, Changchun, Jilin, 130024, P. R. China.
Key Laboratory for UV Light-Emitting Materials and Technology, Northeast Normal University, Ministry of Education, Changchun, Jilin, 130024, P. R. China.
Adv Mater. 2019 Jan;31(4):e1804766. doi: 10.1002/adma.201804766. Epub 2018 Nov 29.
Conventional ion batteries utilizing metallic ions as the single charge carriers are limited by the insufficient abundance of metal resources. Although supercapacitors apply both cations and anions to store energy through absorption and/or Faradic reactions occurring at the interfaces of the electrode/electrolyte, the inherent low energy density hinders its application. The graphite-cathode-based dual-ion battery possesses a higher energy density due to its high working potential of nearly 5 V. However, such a battery configuration suffers from severe electrolyte decomposition and exfoliation of the graphite cathode, rendering an inferior cycle life. Herein, a new surface-modification strategy is developed to protect the graphite cathode from the anion salvation effect and the deposition derived from electrolyte decomposition by generating an artificial solid electrolyte interphase (SEI). Such SEI-modified graphite exhibits superior cycling stability with 96% capacity retention after 500 cycles under 200 mA g at the upper cutoff voltage of 5.0 V, which is much improved compared with the pristine graphite electrode. Through several ex situ studies, it is revealed that the artificial SEI greatly stabilizes the interfaces of the electrode/electrolyte after reconstruction and gradual establishment of the optimal anion-transport path. The findings shed light on a new avenue toward promoting the performance of the dual-ion battery (DIB) and hence to make it practical finally.
传统的离子电池利用金属离子作为单一的电荷载体，受到金属资源丰富度不足的限制。虽然超级电容器通过在电极/电解质界面处发生的阳离子和阴离子的吸收和/或法拉第反应来存储能量，但其固有低能量密度限制了其应用。基于石墨阴极的双离子电池具有更高的能量密度，因为其工作电位接近 5 V。然而，这种电池结构由于严重的电解质分解和石墨阴极的剥离，导致循环寿命不佳。在此，开发了一种新的表面修饰策略，通过生成人工固体电解质界面（SEI）来保护石墨阴极免受阴离子溶剂化效应和电解质分解导致的沉积的影响。经过 500 次循环，在 5.0 V 的上限截止电压下以 200 mA g 的电流密度下，经过修饰的石墨具有优异的循环稳定性，容量保持率为 96%，与原始石墨电极相比有了很大的提高。通过几项原位研究表明，人工 SEI 在重建和逐渐建立最佳阴离子传输路径后，极大地稳定了电极/电解质的界面。这些发现为提高双离子电池（DIB）的性能开辟了新途径，最终使其具有实际应用价值。
