By replacing the inert, strongly positive electrostatic potential of TTE with the active, weakly positive electrostatic potential of MDFSA, thermally resistant interfacial films are formed, enhancing the battery's performance at high temperatures.

Lithium difluorophosphate (LiDFP) is used as an electrolyte additive to improve the electrochemical performances of LiNi_0.5Co_0.2Mn_0.3O₂ (NCM523)/graphite cells operating at a high charging cutoff voltage. LiDFP additive generates a more uniform, extremely stable, and lower resistance passivation film on the cathode surface. This passivation film not only suppresses the subsequent decomposition of electrolyte, but also prevents the dissolution of transition metal ions from NCM523 particles, resulting in improved cyclic stability and discharge capability of NCM523/graphite cells. With electrolyte contained 1.0 wt% LiDFP, the 18650 batteries achieves a capacity retention of 88.2% after 300 cycles at 3.0∼4.4 V and 90.0% after 200 cycles at 3.0∼4.45 V, comparing to 77.9% and 66.3% of the batteries without additive.

The real-world application of Li–S batteries is challenged with the problems of the shuttle effect of lithium polysulfides (LiPSs) and sluggish reaction kinetics. Herein, a porous MoN@nitrogen-doped carbon (MoN-NC) nano-octahedron with a bicontinuous intertwined MoN and NC porous structure was designed as a novel S host material for Li–S batteries. With hierarchical pore structures, the NC immobilized the LiPSs by physical-chemical confinement. Moreover, the continuous MoN framework demonstrated excellent chemisorption with LiPSs as well as the electrocatalysis of the LiPS redox reactions, which was confirmed by our experimental and theoretical results. Due to the synergetic effect of the NC and MoN, the S/MoN-NC cathode with a high S content up to 77% exhibited greatly enhanced electrochemical performances. At 0.5C, the S/MoN-NC cathode delivered a long life of 895 mA h g⁻¹ after 350 cycles, which was much higher than that of its S/MoN and S/NC counterparts (71% and 49% after 100 cycles, respectively). At a high current density of 2C, the specific capacity of S/MoN-NC was 3.2 and 1.3 times higher than that of its S/MoN and S/NC counterparts, respectively. Remarkably, with the increase in the S loading up to 6.5 mg cm⁻², the high capacity retention was still maintained (0.059% capacity decay over 200 cycles). This study gives useful guidance to enable high-energy and high-power Li–S batteries for practical applications.