Fig. 1

(a) Discharge curves at -40 ℃ and three different discharge rates[17]; (b) Cycle performance operating at various temperatures[18]; (c) Ionic conductivity at different temperatures[19]; (d) Capacity retention ratio in respect to the steady state value of 115 mAh/g at the various currents and temperatures[20]"

Fig. 2

(a) Solvation structure of COE and PM-2 electrolyte[22]; (b) Specific capacity-voltage diagram of PM-2 electrolyte over a wide temperature range[22]; (c) The illustration of the electron withdrawing effect of F atoms in the EA-2F solvent molecule and the corresponding coordination chemistry of the ethoxy side difluoro-substitution group (—OCH2CF2H)[23]; (d) Illustrations of fluorinated carbonate electrolytes. The transparent blue spheres indicate the solvation structure; (e) The different affinities between varied solvents and Li+; (f) The nonflammability and high electrochemical stability of designed electrolyte; (g) The expected electrochemical behaviors of tamed electrolyte at the electrode and electrolyte interface[24]"

Fig. 3

(a) The cycle performance of pouch cells in the E-control and dual-salt electrolytes at -20 ℃ at a charge rate of 4C and discharge rate of 0.5 C; (b) Interfacial stability and low-temperature performance of a 200 mAh Gr||NCM523 pouch cell. Cycle performance under -20 ℃ at 0.1C charge and 0.2C discharge[34]; Practicability of the dual-salt electrolyte for graphite||LCO pouch cells; (c) 2C rate under -20 ℃; (d) 1 Ah pouch cell cycle performance under -50 ℃[36]"

Fig. 4

(a) The temperature-dependent discharge profiles of Gr||NCM811 pouch cells with RT charge-LT discharge protocol[39]; (b) Charge-discharge curves of the pouch cells using the 1.5 mol/L MTOS electrolyte and commercial electrolyte at LT (0.1C)[39]; (c) Temperature dependence of ionic conductivities of electrolyte solutions adopting the additives[40]; (d) Temperature-dependent coulombic efficiency measurements at -60 ℃[41]; (e) Cycling performance of Li||NCM811 cells with THP/FEC at -40 ℃ and 4.5 V[42]"

Fig. 5

Diagram of weakly solvated electrolyte[50]"

Fig. 6

(a) Different binding energies of Li+-DME、Li+-2-MeTHF、Li+-THP、Li+-1,4-DX and Li+-FSI-[51]; (b) Cycling performance of Li||NCM811 cells with THP/FEC at -40 ℃ and 4.5 V[42]; (c) Cycle performance of 2.7 Ah Li||NCM811 pouch ceels using THP/FEC and EC/DEC electrolytes at 20 ℃ and 4.5V[42]"

Fig. 7

Comparison of (a) capacitance and (b) energy density of different works mainly in low temperature region[55]; (c) Temperature range of new ionic liquid mixture electrolyte[58]"

Fig. 8

(a) Diagram of a safe LPG electrolyte based on 1,1,1, 2-tetrafluoroethane and pentafluoroethane[59]; (b) The CE of Li-metal plating/strippingin various electrolytes at different temperatures[59]; (c) Measured ionic conductivities of the investigated electrolytes at different temperatures[60]; (d) Measured electrochemical performance at a wide-temperature range of 1 mol/L LiBF4-Me2O-PC[60]; (e) Ionic conductivity of liquefied gas electrolytes with different salt and cosolvent concentrations[61]"

Fig. 9

(a) Cycling performance Li||LCO with lean Li inventory using MPE-TFME-2.3 electrolyte at -60 ℃ and -40 ℃[62]; (b) Discharge performance of Li||LMO cells at 0.1C at -70 ℃[63]; (c) Discharge profiles of Li||NCA cells using 1.28 mol/L LiFSI-FEC/FEMC-D2 electrolyte at different temperatures[24]; (d) Discharge capacities of Li||NCA cells using 1.28 mol/L LiFSI-FEC/FEMC-D2 and 1.0 mol/L LiPF6-EC/DMC electrolytes at different temperatures[24]"

Table 1

Performance parameters of different electrolyte systems"