Understanding the Effects of Interfacial Lithium Ion Concentration on Lithium Metal Anode

Abstract

Despite the development of multidimensional state-of-the-art electrode materials for constructing better lithium metal anodes (LMAs), the key factors influencing the electrochemical performance of LMAs are still poorly understood. Herein, it is demonstrated that the local lithium ion concentration at the interface between the electrode and electrolyte exerts significant influence on the electrochemical performance of LMAs. The local ion concentration is multiplied by introducing pseudocapacitive nanocarbons (PNCs) containing numerous heteroatoms, because PNCs can store large numbers of lithium ions in a pseudocapacitive manner, and promote the formation of an electrochemical double layer. The high interfacial lithium ion concentration induces the formation of lithium-rich inorganic solid-electrolyte-interface layers with high ionic conductivities, and facilitates sustainable and stable supplies of lithium ion charge carriers on the overall active surfaces of the PNCs. Accordingly, the PNC-induced LMA exhibits high Coulombic efficiencies, high rate capabilities, and stable cycling performance.

Modified lithium metal anodeviaanion-planting protection mechanisms for dendrite-free long-life lithium metal batteries

“…S20†), which could be assigned to Li 2 O, alkyl lithium (RO̲–Li, R = alkyl), and Li 2 CO 3 , C̲O, and C–O̲, respectively. 67–69 The composition distribution and their relative proportions here were essentially identical to that in the C 1s spectra, in which CO and lithium carbonate were the main forms on the surface. Some alkyl lithium also appeared owing to the polyether carbon species.…”

“…After 5 min of etching, the main C-containing components changed to the RO̲–Li, indicating the polymeric feature was present throughout the entire SEI. 18,69 Moreover, an obvious peak of Li 2 O arose in the post-etched SEI (528.2 eV). Since lithium oxides were the native species on pristine Li metal, this demonstrated that the metallic Li deposition or pristine Li substrate was exposed after etching.…”

Measuring the Nucleation Overpotential in Lithium Metal Batteries: Never Forget the Counter Electrode!

“…Moreover, the nucleation overpotential is considered a significant parameter in measuring the lithiophilicity of the modified non-Li substrate. [25][26][27] Based on the previous reports, the initial Li nucleation overpotential is quite high for the conventional substrates such as Ni or Cu foam, since these materials have little affinity for Li. 13,28 By contrast, this study shows that the overpotential at the Li counter electrode can mainly explain the initial decrease in voltage of the cell below 0.2 V. On the Ni foam, there is a constant voltage decrease to a steady-state level, which indicates that the energy barrier for extracting Li on the surface of Li is much higher compared to the energy barrier for forming nucleation sites (E working -E counter < E counter ).…”

Sulfur‐doped hard carbon hybrid anodes with dual lithium‐ion/metal storage bifunctionality for high‐energy‐density lithium‐ion batteries

“…This enables a sharp increase in specific energy density and 100% CEs during cycling. [24][25][26][27][28] However, critical issues persist in the application of LMAs, such as unexpected dendritic lithium metal growth, consecutive electrolyte consumption, large volume changes, low CEs, a substantial increase of overpotentials, and poor cell stabilities. [29][30][31][32] These issues can be mitigated by introducing three-dimensional-structured lithiophilic electrodes (3D-LEs); their high lithiophilicity and large surface areas can facilitate homogeneous lithium metal nucleation and growth in extensive surfaces, and the inner spaces of the 3D structure can accommodate lithium metals with insignificant changes in volume.…”

“…High‐capacity LMAs can deliver a significantly more number of charges than those of typical graphite through a small amount of mass loading and can recover the lithium loss that occurs during the charge/discharge process. This enables a sharp increase in specific energy density and 100% CEs during cycling 24–28 . However, critical issues persist in the application of LMAs, such as unexpected dendritic lithium metal growth, consecutive electrolyte consumption, large volume changes, low CEs, a substantial increase of overpotentials, and poor cell stabilities 29–32 .…”