Journal
NANO RESEARCH
Volume 14, Issue 10, Pages 3585-3597Publisher
TSINGHUA UNIV PRESS
DOI: 10.1007/s12274-021-3643-1
Keywords
carbon nitride; Debye length; lithiophilic coating; porous structure; Li negative electrode
Categories
Funding
- National Key R&D Program of China [2016YFF0204302]
- National Natural Science Foundation of China [51872305, 52001320]
- S&T Innovation 2025 Major Special Programme of Ningbo [2018B10081]
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This study introduces a physical-chemical synergic regulation strategy using porous carbon nitride microspheres (PCNMs) to fabricate a uniform lithiophilic coating layer on Cu/Li foil, which can effectively homogenize the Li+ flux and contribute to establishing a robust and stable solid electrolyte interphase (SEI) layer based on the Debye length law. This strategy leads to dendrite-free Li plating, low nucleation overpotential, and stable Li plating/stripping cycling performance in lithium symmetric cells, as well as high capacity retention and remarkable rate capability in full cells paired with NCM 811 positive electrodes.
Uncontrollable dendrite growth resulting from the non-uniform lithium ion (Li+) flux and volume expansion in lithium metal (Li) negative electrode leads to rapid performance degradation and serious safety problems of lithium metal batteries. Although N-containing functional groups in carbon materials are reported to be effective to homogenize the Li+ flux, the effective interaction distance between lithium ions and N-containing groups should be relatively small (down to nanometer scale) according to the Debye length law. Thus, it is necessary to carefully design the microstructure of N-containing carbon materials to make the most of their roles in regulating the Li+ flux. In this work, porous carbon nitride microspheres (PCNMs) with abundant nanopores have been synthesized and utilized to fabricate a uniform lithiophilic coating layer having hybrid pores of both the nano- and micrometer scales on the Cu/Li foil. Physically, the three-dimensional (3D) porous framework is favorable for absorbing volume changes and guiding Li growth. Chemically, this coating layer can render a suitable interaction distance to effectively homogenize the Li+ flux and contribute to establishing a robust and stable solid electrolyte interphase (SEI) layer with Li-F, Li-N, and Li-O-rich contents based on the Debye length law. Such a physical-chemical synergic regulation strategy using PCNMs can lead to dendrite-free Li plating, resulting in a low nucleation overpotential and stable Li plating/stripping cycling performance in both the Li parallel to Cu and the Li parallel to Li symmetric cells. Meanwhile, a full cell using the PCNM coated Li foil negative electrode and a LiFePO4 positive electrode has delivered a high capacity retention of similar to 80% after more than 200 cycles at 1 C and achieved a remarkable rate capability. The pouch cell fabricated by pairing the PCNM coated Li foil negative electrode with a NCM 811 positive electrode has retained similar to 73% of the initial capacity after 150 cycles at 0.2 C.
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