Cation-disordered Li2FeTiO4 nanoparticles with multiple cation and anion redox for symmetric lithium-ion batteries

• Published in: Chinese chemical letters 2024-08, p.110346, Article 110346
• Main Authors: Ma, Wenjie, Tang, Yakun, Zhang, Yue, Liu, Lang, Tang, Bin, Jia, Dianzeng, Cao, Yuliang
• Format: Article
• Language: English
• Subjects: Cation-disordered; Li2FeTiO4; Regulating nucleation rate; Reversible cationic and anionic redox; Symmetric lithium-ion batteries
• ISSN: 1001-8417
• DOI: 10.1016/j.cclet.2024.110346

Symmetric secondary batteries are expected to become promising storage devices on account of their low cost, environmentally friendly and high safety. Nevertheless, the further development of symmetric batteries needs to rely on bipolar electrodes with superior performance. Cation-disordered rocksalt (DRX) Li2FeTiO4 shows promising properties as symmetric electrodes, based on the ability of iron to undergo multiple electrochemical reactions over a wide voltage window. Unfortunately, this cation-disordered structure would not provide a cross-path for the rapid migration of Li+, ultimately resulting in inferior electrochemical dynamics and cycle stability. Herein, Li2FeTiO4 nanoparticles assembled by ultrafine nanocrystals are synthesized via a sol-gel method through an orderly reaction regulation strategy of precursor reactants. Such ultrafine nanocrystals increase the active sites to promote the reversibility of multi-cationic (e.g., stable Fe2+/Fe3+, Ti3+/Ti4+ and moderated Fe3+/Fe4+) and anionic redox, and maintain the DRX structure well during the cycling process. The half cells with nano-sized Li2FeTiO4 as cathode/anode exhibit a high reversible capacity of 127.8/500.8 mAh/g, respectively. Besides, the Li2FeTiO4//Li2FeTiO4 symmetric full cell could provide a reversible capacity of 95.4 mAh/g at 0.1 A/g after 200 cycles. This hierarchical self-assembly by nanocrystal strategy could offer effective guidance for high-performance electrode design for rechargeable secondary batteries. Li2FeTiO4 nanoparticles assembled by ultrafine nanocrystals, are synthesized via a sol-gel method. Hierarchical self-assembly structure of nanocrystals provides diversified diffusion channels and increases the active sites, enhancing the reversibility of multi-ion redox and kinetic behavior. [Display omitted]