Unlocking Charge Transfer Limitation toward Advanced Low-Temperature Sodium-Ion Batteries

Abstract

Sodium-ion batteries (SIBs) are recognized as promising large-scale energy storage systems but suffer from sluggish kinetics at low temperatures. Herein, we proposed a carbon nanotubes-modified P2-Na_0.67Mn_0.67Ni_0.33O₂ (NMNO-CNTs) cathode and tetrahydrofuran (THF)-containing dimethyl-based electrolyte to unlock the charge transfer limitation of SIBs at low temperatures. A highly conductive network constructed by CNTs ensures fast surface electron transfer. The introduction of THF enables an anion-rich solvation structure, which facilitates the formation of a robust NaF-rich electrode–electrolyte interface with accelerated desolvation and uniform Na deposition. As a result, the Na||NMNO-CNTs cell delivers a capacity of 83.4 mAh g^–1 even after 3600 cycles with a decay rate of 0.002% per cycle at −40 °C. More importantly, the hard carbon||NMNO-CNTs full cell exhibits an energy density of 237.6 Wh kg^–1 with 86.5% retention after 1500 cycles at −40 °C. The work highlights the key role of charge transfer kinetics for advanced low-temperature SIBs.