Low Concentration Electrolyte Enabling Cryogenic Lithium–Sulfur Batteries

Abstract

Lithium–sulfur chemistry suffers from poor conversion reaction kinetics, causing low‐capacity utilization of sulfur cathodes, particularly at cryogenic temperatures. Herein, based on low‐cost and abundant commercial sulfur particles directly, a low concentration electrolyte (LCE, 0.1 m) is employed to accelerate lithium–sulfur conversion reaction at low temperatures, demonstrating a broad applicability of this approach. Compared to conventional concentration (1.0 m) electrolytes, the proposed LCE successfully enhances conversion kinetics from Li2S4 to Li2S and restrains shuttle effects of polysulfides, resulting in higher capacity utilizations and more stable cycle performance at 0 and −20 °C. Further interfacial chemistry analyses on cycled electrodes reveal that a hybrid surface layer dominated by organic species as well as some favorable inorganics is constructed in the LCE, demonstrating smaller surface layer resistance. In situ EIS measurements at 0 °C and CV tests reveal main differences of electrode kinetics in 0.1 and 1 m electrolytes, further explaining the differences in working mechanism of two electrolytes. These findings elucidate the roles of LCEs on realizing faster kinetics for cryogenic lithium–sulfur batteries and provide a simple, low‐cost, and widely applicable pathway for achieving high‐performance lithium–sulfur batteries under extreme conditions.

Weakening Li+De‐solvation Barrier for Cryogenic Li–S Pouch Cells

“…The peak current of all electrolytes demonstrates fine linear relationships with the square root of the scan rate, and 0.5 m shows the steepest slope, which means faster kinetics for the batteries with 0.5 m electrolyte. [35,36] We further studied the nucleation of Li 2 S in different LiTFSI concentration electrolytes using a potentiostaic technique at −20 °C. As shown in Figure S10, Supporting Information, 0.5 m demonstrates the highest nucleation current and sharpest peak shape (Figure S10, Supporting Information), implying rapid kinetics of LPS conversion in 0.5 m electrolyte.…”

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

“…8a-blank, the peaks at 284.8, 286.6, 288.8, 290.2, and 292.9 eV corresponded to hydrocarbon (C-C/C-H), polyether carbon (C-O), carbonyl group (C]O), carbonate (Li 2 CO 3 ), and organic uoride (C-F), respectively. 60,[62][63][64][65] The difference in surface composition between the two samples can be clearly observed as more organic components (C-C, C-O, and Li 2 CO 3 ) existed in the SEI of the bare Li anode, which should mainly arise from the decomposition products of the electrolyte solvents. 64,65 In addition, the small amount of C-F present was from the widespread electrochemical decomposition or interfacial adsorption of these anions in lithium salts (LiTFSI, LiD-FOB).…”

“…60,[62][63][64][65] The difference in surface composition between the two samples can be clearly observed as more organic components (C-C, C-O, and Li 2 CO 3 ) existed in the SEI of the bare Li anode, which should mainly arise from the decomposition products of the electrolyte solvents. 64,65 In addition, the small amount of C-F present was from the widespread electrochemical decomposition or interfacial adsorption of these anions in lithium salts (LiTFSI, LiD-FOB). 44,63,65 Further, the spatial distribution of the interface composition was examined aer Ar + sputtering for 300 s (5 min).…”

“…64,65 In addition, the small amount of C-F present was from the widespread electrochemical decomposition or interfacial adsorption of these anions in lithium salts (LiTFSI, LiD-FOB). 44,63,65 Further, the spatial distribution of the interface composition was examined aer Ar + sputtering for 300 s (5 min). The cycled bare Li still displayed its organic-rich property with a higher proportion of carbonaceous compounds (Fig.…”

Advanced Strategies for Improving Lithium Storage Performance under Cryogenic Conditions

“…[209] Wu et al [210] established that low concentration electrolyte has lower viscosity, better wettability, and polysulfide shuttle inhibition at room temperature than high concentration electrolyte. As a result, roomtemperature Li-S batteries are better able to retain cycle capacity and achieve excellent rate capability up to 2 C. Later, they discovered that even at LTs, low-concentration electrolytes provide increased capacity retention, due to the fast conversion kinetics in the process from Li 2 S 4 to Li 2 S. [211] Low-concentration electrolytes offer a useful strategy for producing LT Li-S batteries.…”