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

• Published in: Small (Weinheim an der Bergstrasse, Germany) Germany), 2023-05, Vol.19 (21), p.e2207638-n/a
• Main Authors: Hou, Liuyan, Liu, Ting, Wang, Helin, Bai, Miao, Tang, Xiaoyu, Wang, Zhiqiao, Zhang, Min, Li, Shaowen, Wang, Tianyu, Zhou, Kefan, Ma, Yue
• Format: Article
• Language: English
• Subjects: Anodes; Commercialization; Diffusion rate; high‐rate performance; homogeneous presodiation strategy; initial coulombic efficiency; Kinetics; microstructural tailoring; Na diffusion kinetics; Nanotechnology; Prototyping; Sodium; Sodium-ion batteries
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.202207638

Hard 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. A multiscale modification strategy of hard carbon (HC) is proposed by exquisitely tuning the microstructure on the particle level as well as supplementing extra Na+ reservoir for the electrode through an insulation‐buffer‐layer assisted presodiation therapy. The coulombic efficiency of HC anode is precisely controlled till the close‐to‐unit value and Na+ diffusivity is drastically enhanced by two orders of magnitude at the low‐potential region.