Boosting the Reversible, High‐Rate Na+ Storage Capability of the Hard Carbon Anode Via the Synergistic Structural Tailoring and Controlled Presodiation

Abstract

AbstractHard carbons (HCs) are extensively investigated as the potential anodes for commercialization of sodium‐ion batteries (SIBs). However, the practical deployment of HC anode suffers from the retarded Na+ diffusion at the high‐rate or low‐temperature operation scenarios. Herein, a multiscale modification strategy by tuning HC microstructure on the particle level as well as replenishing extra Na+ reservoir for the electrode through a homogeneous presodiation therapy is presented. Consequently, the coulombic efficiency of HC anode can be precisely controlled till the close‐to‐unit value. Detailed kinetics analysis observes that the Na+ diffusivity can be drastically enhanced by two orders of magnitude at the low potential region (< 0.1 V vs. Na+/Na), which accelerates the rate‐limiting step. As pairing the presodiated HC anode (≈5.0 ± 0.2 mg cm−2) with the NaVPO4F cathode (≈10.3 mg cm−2) in the 200 mAh pouch cell, the optimal balance of the cyclability (83% over 1000 cycles), low‐temperature behavior till −40 °C as well as the maximized power output of 1500 W kg−1 can be simultaneously achieved. This synergistic modification strategy opens a new avenue to exploit the reversible, ultrafast Na+ storage kinetics of HC anodes, which thus constitutes a quantum leap forward toward high‐rate SIB prototyping.