High‐Energy‐Density Lithium Metal Batteries with Impressive Li⁺ Transport Dynamic and Wide‐Temperature Performance from −60 to 60 °C

Abstract

temperature range between −20 and 55 °C. [3][4][5] Especially LIBs hardly work when the temperature is below −30 °C because of commercial carbonate electrolytes, which often include LiPF 6 salt, cyclic ethylene carbonate (EC), and linear carbonate solvents (such as dimethyl carbonate (DMC), diethyl carbonate (DEC)). The commercial carbonate electrolytes usually exhibit high freezing points and high viscosity at low temperature, resulting in sluggish Li + transport and charge transfer kinetics at low temperature. [6][7][8] This severely limits their application in electric vehicles, defense applications, and space exploration. The requirements for developing high-energydensity and wide-temperature energy storage devices become very urgent. [9,10] To improve energy density, lithium (Li) metal batteries (LMBs) containing Li metal anode and nickel (Ni)-rich LiNi x Co y Mn z O 2 (x ≥ 0.9) cathode have attracted extensive attention due to low electrochemical potential of Li metal (−3.04 V compared to standard hydrogen electrode) and high specific capacity (3860 mA h g −1 of Li metal, >200 mA h g −1 of LiNi 0.9 Co 0.05 Mn 0.05 O 2 ). [11][12][13] However, LiPF 6 salt is easily decomposed to produce HF and carbonate solvents are continuously oxidized/reduced at electrode/electrolyte interface, which will cause serious corrosion to Ni-rich cathode and Li metal anode. [14] As a result, during the cycling process, Li dendrites High-energy-density Li metal batteries (LMBs) with Nickel (Ni)-rich cathode and Li-metal anode have attracted extensive attention in recent years. However, commercial carbonate electrolytes bring severe challenges including poor cycling stability, severe Li dendrite growth and cathode cracks, and narrow operating temperature window, especially hardly work at below −40 °C. In this work, a 2.4 m lithium difluoro(oxalato)borate (LiDFOB) in ethyl acetate (EA) solvent with 20 wt% fluorocarbonate (FEC) (named 2.4m-DEF) is designed to solve Li + transport dynamic at low temperature and improve interfacial stability between electrolyte with Li anode or Ni-rich cathode. Beneficial lower freezing point, lower viscosity, and higher dielectric constant of EA solvent, the electrolyte exhibits excellent Li + transport dynamic. Relying on the unique Li + solvation structure, more DFOB − anions and FEC solvents are decomposed to establish a stable solid electrolyte interface at electrolyte/ electrode. Therefore, LiNi 0.9 Co 0.05 Mn 0.05 O 2 (NCM90)/Li LMB with 2.4m-DEF enables excellent rate capability (184 mA h g −1 at 30 C) and stable cycling performance with ≈93.7% of capacity retention after 200 cycles at 20 C and room temperature. Moreover, the NCM90/Li LMB with 2.4m-DEF exhibits surprising ultra-low-temperature performance, showing 173 mA h g −1 at −40 °C and 152 mA h g −1 at −60 °C, respectively.

Rational Design of F-Modified Polyester Electrolytes for Sustainable All-Solid-State Lithium Metal Batteries

“…In addition, it is observed that the LiF layer on the Li foil of Li/C6–C5–3F–Li/Li is obviously thicker and less uniform than that of Li/C2–C9–3F–Li/Li, which is consistent with the results observed in XPS. These features can be attributed to the reduction of oxalate units and the generation of Li-metal stable dienolated lithium units (Figure j), which work together with trifluoroacetate and inhibit the interfacial reactions. , On the contrary, the reduction of C6-diester leads to the polymer chains’ degradation with the generation of CO gas, and the passivation of Li metal is mainly dependent on the terminal trifluoroacetates, resulting in a thick and inhomogeneous layer of LiF. , …”

“…46,47 On the contrary, the reduction of C6-diester leads to the polymer chains' degradation with the generation of CO gas, and the passivation of Li metal is mainly dependent on the terminal trifluoroacetates, resulting in a thick and inhomogeneous layer of LiF. 48,49 Electrochemical Performances of ASS Li-Metal Cells. The onset oxidation voltages of SPEs are critical for tolerating the high-voltage cathodes and so improving the energy density of ASS batteries.…”

Two‐Step Catalytic Against Polysulfide Shuttling to Enhance Redox Conversion for Advanced Lithium–Sulfur Batteries

“…Phosphorus atoms can take electrons from metal atoms due to high electronegativity, which can effectively adsorb positively charged ions. [21] Transition metal phosphates have a high catalytic activity, which can effectively accelerate the conversion of LiPSs. [22] Among them, MoP possesses better electrical conductivity, which can promote the rapid transfer of electrons and suppress the shuttle effect of LiPSs.…”

Transition Metal Phosphides: The Rising Star of Lithium–Sulfur Battery Cathode Host

“…III) The liquid-to-solid conversion of Li 2 S 4 to Li 2 S 2 , and IV) the final inter-solid conversion of Li 2 S 2 to Li 2 S. Among them, as the key limiting step, stage (iii) provides nearly half of the theoretical overall discharge capacity (836 mA h g −1 ) (Figure 1b), while the remaining stages all have a theoretical capacity of 209 mA h g −1 . [8] Therefore, it is of great practical significance to design sulfur fixation carrier materials with different efficacies for specific electrochemical behavior and reaction stages. [8] Copyright 2023, Wiley-VCH.…”

“…[8] Therefore, it is of great practical significance to design sulfur fixation carrier materials with different efficacies for specific electrochemical behavior and reaction stages. [8] Copyright 2023, Wiley-VCH.…”