Nitrofullerene, a C₆₀-based Bifunctional Additive with Smoothing and Protecting Effects for Stable Lithium Metal Anode

Abstract

Practical applications of lithium metal anodes are gravely impeded by inhomogeneous lithium deposition, which results in dendrite growth. Electrolyte additives are proven to be effective in improving performance but usually serve only a single function. Herein, nitrofullerene is introduced as a bifunctional additive with a smoothing effect and forms a protective solid electrolyte interphase (SEI) layer on stable lithium metal anodes. By design, nitro-C 60 can gather on electrode protuberances via electrostatic interactions and then be reduced to NO 2 − and insoluble C 60 . Next, the C 60 anchors on the uneven groove of the lithium surface, resulting in a homogeneous distribution of Li ions. Finally, NO 2 − anions can react with metallic Li to build a compact and stable SEI with high ion transport. With a 5 mM nitro-C 60 additive, Li−Li symmetric cells show superior cycle stability in both carbonate and ether electrolytes, Li−sulfur batteries with a high cathode loading (10.6 mg cm −2 , 6 mAh cm −2 ) can achieve improved cycle retention of 63.2% over 100 cycles in a carbonate electrolyte, and full cells paired with a high-areal-capacity LiNi 0.6 Co 0.2 Mn 0.2 O 2 cathode (3.5 mAh cm −2 ) exhibit a significantly enhanced cycle lifespan even under lean electrolyte conditions.

Robust Artificial Solid‐Electrolyte Interfaces with Biomimetic Ionic Channels for Dendrite‐Free Li Metal Anodes

“…In response to these challenges, various strategies, such as the use of different solvents, [ 10–12 ] the optimization of Li salt concentrations, [ 13–15 ] the addition of functionalized additives, [ 16–18 ] and the design of electrolyte nanostructures, [ 19–21 ] have been proposed to construct a stable SEI film on the surface of Li metal anodes. These modifications of the in‐situ formed SEI films could enable uniform Li deposition and suppress Li dendrite growth in initial cycles.…”

Polycationic Polymer Layer for Air‐Stable and Dendrite‐Free Li Metal Anodes in Carbonate Electrolytes

“…In N 1s spectra, PIL‐induced SEI layers show two peaks: the one at 401.7–402.3 eV corresponding to N + on the side chains of the PIL, and the other at 398.9–399.1 eV attributed to LiN bond in Li 3 N ( Figure a). [ 12a,19 ] Li 3 N is a decomposed product of TFSI anion, and no Li 3 N is observed in the SEI formed on the bare Cu due to the lack of TFSI anions. The accumulated TFSI anions in the polycationic film likely undergo reduction reaction and the decomposed Li 3 N constitutes the SEI layer, which is also observed in the SEI layer formed in the electrolyte with IL additive.…”

“…Steady, flat, and smooth voltage profiles are observed from the enlarged pictures, with overpotential as low as ≈23 mV during the entire Li plating/stripping process, without PDDA-TFSI layer at 10 mAh cm −2 and 1 mA cm −2 (c), and 5 mAh cm −2 and 5 mA cm −2 (d). e) Comparison of areal capacities and cycling stabilities of PIL@Li with the reported protective layer, [21,22] Li host/ composite, [23] and electrolyte modification [19,24] strategies (all the symmetric cells are cycled in the carbonate-based electrolytes). f-i) Top surface and cross-sectional SEM images of bare Li (f,g) and PDDA-TFSI@Li (h,i) after 100 h cycling at 1 mAh cm −2 and 1 mA cm −2 .…”

Polysiloxane Cross‐Linked Mechanically Stable MXene‐Based Lithium Host for Ultrastable Lithium Metal Anodes with Ultrahigh Current Densities and Capacities

“…To the best of our knowledge, the long cycling stability (3000 h) at such a high current density (20 mA cm −2 ) and areal capacity (10 mAh cm −2 ) of the Li@C 0.5 ‐MXene/AgNW anode is superior to all previously reported Li composite anodes (Figure 4c; Table S2, Supporting Information). [ 9,10,32,40,42,46,49,60–77 ] It also outperforms all Li metal anodes stabilized by other strategies (Table S3, Supporting Information), [ 15,16,20,21,78–86 ] such as SEI layer modification, [ 15,16,78–82 ] separator modification, [ 20,21 ] and electrolyte modification. [ 83–86 ] Moreover, similar to most previously published works, our Li@C 0.5 ‐MXene/AgNW composite anode exhibited better cycling stability in ether based electrolyte than that in carbonate based electrolytes (Figure S8, Supporting Information).…”