Building better lithium-sulfur batteries: from LiNO3 to solid oxide catalyst

Abstract

Lithium nitrate (LiNO3) is known as an important electrolyte additive in lithium-sulfur (Li-S) batteries. The prevailing understanding is that LiNO3 reacts with metallic lithium anode to form a passivation layer which suppresses redox shuttles of lithium polysulfides, enabling good rechargeability of Li-S batteries. However, this view is seeing more challenges in the recent studies, and above all, the inability of inhibiting polysulfide reduction on Li anode. A closely related issue is the progressive reduction of LiNO3 on Li anode which elevates internal resistance of the cell and compromises its cycling stability. Herein, we systematically investigated the function of LiNO3 in redox-shuttle suppression, and propose the suppression as a result of catalyzed oxidation of polysulfides to sulfur by nitrate anions on or in the proximity of the electrode surface upon cell charging. This hypothesis is supported by both density functional theory calculations and the nitrate anions-suppressed self-discharge rate in Li-S cells. The catalytic mechanism is further validated by the use of ruthenium oxide (RuO2, a good oxygen evolution catalyst) on cathode, which equips the LiNO3-free cell with higher capacity and improved capacity retention over 400 cycles.

Anode Interface Engineering and Architecture Design for High‐Performance Lithium–Sulfur Batteries

“…In addition, nitrate ions (NO 3 − ) could catalyze the conversion of polysulfide to elemental sulfur near the end of the charging process . The strong “bond‐like” interaction between NO 3 − and polysulfides suppressed diffusion of polysulfides . However, the ability of LiNO 3 ‐containing electrolyte to suppress the shuttle effect and dendrite growth is limited.…”

Understanding the Role of Nano‐Aluminum Oxide in All‐Solid‐State Lithium‐Sulfur Batteries

“…The shade changes from brownish green to colorless demonstrating strong interaction of the ceramic particle with PS, thus the ability of Al 2 O 3 to adsorb PS on the surface and remove them from the liquid media. Even if other metal oxides such as Nb 2 O 5 or RuO 2 have been proven to be stronger PS adsorbers, in comparison, Al 2 O 3 has an unique balanced function between PS adsorption properties and Li 0 stabilization properties, making it a promising choice for ASSLSBs.…”

Effective Bipyridine and Pyrazine‐Based Polysulfide Dissolution Resistant Complex Framework Material Systems for High Capacity Rechargeable Lithium–Sulfur Batteries

“…Figure c,d corresponds to the specific capacity plots of 1st, 2nd, 10th, 25th, and 150th charge–discharge profiles of S‐Cu‐bpy‐CFM and S‐Cu‐pyz‐CFM at 0.2 C rate. The discharge profiles of both the CFMs show a smaller plateau at 2.35 V corresponding to the formation of the higher‐order polysulfide during the initial stages of lithiation Li 2 S n ( n = 4–8) and a wider plateau at 2.05 V that, in turn, corresponds to the formation of lower‐order lithium sulfides Li 2 S n ( n < 4). Similar plateaus at 2.4 and 2.25 V are observed in the charge cycles corresponding to the delithiation of Li 2 S to form the lower‐order polysulfides and corresponding higher‐order polysulfides, respectively, ultimately resulting in the formation of sulfur.…”