An international research team has developed a new strategy for dendritic-free lithium metal batteries based on the use of interlayer and intralayer atomic channels in graphite formed by pre-tunneling graphite layers. The obtained atomic channels enable the free and rapid diffusion of lithium with enhanced kinetics. Atomic channel.

An open access paper on this work was published in the RSC journal Energy and Environmental Science.

Although lithium has attractive properties as a negative electrode material in energy storage systems—for example, it has a very high theoretical capacity of 3860 mAh g-1—but practical applications are still hindered by safety issues caused by lithium dendrite growth.

Due to unsatisfactory electrochemical performance and serious safety issues, the uneven and uncontrollable accumulation of lithium at the electrode/electrolyte interface always leads to the notorious dendrite growth and limits its further application. Since lithium diffusion on the anode surface is much faster than bulk diffusion, adjusting the diffusion/deposition of lithium on the anode surface is considered to be the mainstream method to induce its uniform deposition.

Previous work focused on the construction of a three-dimensional open structure of the carbon skeleton and/or the introduction of steerable seeds, such as Au, Ag metal nanoparticles and Co and Ni single atoms. Before surface deposition, Li must overcome a huge energy barrier to be embedded in the graphite layer, causing the layer to expand by about 0.2 Å,14,15 and it will be restricted to the typical C6LiC6 state, thereby sacrificing its diffusivity. Therefore, it is rarely considered Graphite blocks are used to carry high-density and rapid lithium flux, and the potential of multi-layer lithium diffusion through graphite layers has not been fully utilized. By using density functional theory (DFT) calculations and in-situ transmission electron microscopy (TEM), Kuhne et al. reported pioneering work. The feasibility of multiple layers of dense lithium between two graphene layers has been demonstrated, which far exceeds the typical C6LiC6 structure. However, the reported embedding and diffusion characteristics of the double-layer graphite sheet are not equivalent to the exfoliated bulk carbon. In addition, their non-scalable material preparation keeps them away from the practical application of high-performance LMBs. Inspired by this work, a new lithium diffusion pathway through bulk carbon can be constructed by pre-tunneling graphite layers. The obtained atomic channels can allow the free and rapid diffusion of ultra-dense lithium, while greatly enhancing the kinetics and safety.

In this contribution, by adopting a molecular tunneling strategy, we have constructed a bulk diffused lithium conductor (BDLC) with abundant atomic channels for ultra-dense lithium transport. By pre-tunneling the graphite layer (interlayer spacing as large as ~7 Å), while introducing voids and lithium-philic sites, the interlayer and intralayer channels for lithium diffusion are established. Different from the traditional surface diffusion/deposition mechanism, the atomic channel can effectively alleviate the dendrite problem caused by uneven surface deposition and achieve rapid bulk diffusion. ——Zhou et al.

Comparison diagram of graphite layer and atomic channels. (a) Typical lithium ion intercalation in the graphite layer and (b) schematic diagram of ultra-dense lithium diffusion in atomic channels. Zhou et al.

Pairing the new negative electrode material with a highly loaded LiFePO4 (LFP) positive electrode can achieve a high area capacity of 3.9 mAh cm-2 and maintain 100% capacity during 370 cycles.

The bulk diffusion strategy will provide a new perspective that is different from conventional surface diffusion, will expand the knowledge about ultra-dense lithium diffusion, and will also redefine the study of lithium dendrite suppression. —Zhou et al.

Zhou Shiyuan, Chen Weixin, Shi Jie, Li Gen, Pei Fei, Liu Sangui, Ye Weibin, Xiao Liangping, Wang Mingsheng, Wang Dan, Qiao Yu, Huang Ling, Xu Guiliang, Liao Honggang, Jian- Feng Chen, Khalil Amine and Shi-Gang Sun ( 2021) "High-efficiency diffusion of ultra-dense lithium through atomic channels for non-dendritic lithium metal batteries" energy environment. science. doi: 10.1039/D1EE02205A

Published on November 15, 2021 in Batteries, Materials | Permalink | Comments (0)

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