Facile Pyrolyzed N‑Doped Binder Network for Stable Si Anodes

Although nanoengineering provides improved stability of Si-based nanostructures, a facile and efficacious method to directly use raw Si practices is still absent. Herein, we report a pyrolyzed N-doped binder network to improve the cycling stability of raw Si particles. Such an N-doped binder network is formed at a conformal pyrolysis condition of the electrode binder using polyacrylonitrile and provides a tight encapsulation of the Si particles with significantly improved cycling stability. In contrast to the single Si particles that pulverize and lose the total capacity at the 20th cycle, the discharge capacity could be retained ∼1700 mA h g^–1 at the 100th cycle for the Si particles imbedded in the pyrolyzed N-doped binder network. Our results demonstrate that such a facile remedy could significantly improve the cycling stability of raw Si particles for high-energy-density lithium-ion batteries

Li₂O‑Reinforced Cu Nanoclusters as Porous Structure for Dendrite-Free and Long-Lifespan Lithium Metal Anode

A nanostructured protective structure, pillared by the copper nanoclusters and in situ filled with lithium oxide in the interspace, is constructed to efficiently improve the cyclic stability and lifetime of lithium metal electrodes. The porous structure of copper nanoclusters enables high specific surface area, locally reduced current density, and dendrite suppressing, while the filled lithium oxide leads to the structural stability and largely extends the electrode lifespan. As a result of the synergetic protection of the proposed structure, lithium metal could be fully discharged with efficiency ∼97% for more than 150 cycles in corrosive alkyl carbonate electrolytes, without dendrite formation. This approach opens a novel route to improve the cycling stability of lithium metal electrodes with the appropriate protective structure

Effect of LiFSI Concentrations To Form Thickness- and Modulus-Controlled SEI Layers on Lithium Metal Anodes

Improving the cyclic stability of lithium metal anodes is of particular importance for developing high-energy-density batteries. In this work, a remarkable finding shows that the control of lithium bis­(fluorosulfonyl)­imide (LiFSI) concentrations in electrolytes significantly alters the thickness and modulus of the related SEI layers, leading to varied cycling performances of Li metal anodes. In an electrolyte containing 2 M LiFSI, an SEI layer of ∼70 nm that is obviously thicker than those obtained in other concentrations is observed through <i>in situ</i> atomic force microscopy (AFM). In addition to the decomposition of FSI^– anions that generates rigid lithium fluoride (LiF) as an SEI component, the modulus of this thick SEI layer with a high LiF content could be significantly strengthened to 10.7 GPa. Such a huge variation in SEI modulus, much higher than the threshold value of Li dendrite penetration, provides excellent performances of Li metal anodes with Coulombic efficiency higher than 99%. Our approach demonstrates that the FSI^– anions with appropriate concentration can significantly alter the SEI quality, establishing a meaningful guideline for designing electrolyte formulation for stable lithium metal batteries