Tri-phase (1-x-y) Li2FeSiO4·xLiFeBO3·yLiFePO4 nested nanostructure with enhanced Li-storage properties

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 358; pp. 786 - 793
• Main Authors: Tian, Meiyue, Hu, Lin, Huang, Zhe, Li, Mingrui, Yang, Jinlong, Wang, Zhe, Li, Jiannian, Lin, Xin, Mu, Shichun
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.02.2019
• Subjects: High rate performance; Li2FeSiO4; LiFeBO3; LiFePO4; Lithium-ion battery; Stability; Lithium-ion battery; Li2FeSiO4; Stability; LiFeBO3; High rate performance; LiFePO4
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2018.10.059

A triple phase 0.92LFS·0.04LFB·0.04LFP nested nanostructure is successfully synthesized through an in-situ sol-gel method and exhibits excellent Li+ storage properties including high specific reversible capacity (258.7 mAh g−1, 0.1 C, 1.5–4.8 V, equivalent to 1.56 Li+ intercalation) and long cycle stability (capacity retention rate of 96% after 300 cycles at 5 C). [Display omitted] •Tri-phase (1-x-y) Li2FeSiO4·xLiFeBO3·yLiFePO4 nested nanostructures are first synthesized by an in-situ sol-gel method.•(1-x-y) LFS·xLFB·yLFP possesses low charge transfer impedance and Li+ diffusion energy barrier.•Compared with LFS, 0.92LFS·0.04LFB·0.04LFP exhibits greatly improved Li storage performance.•The participation of LFP avoids the instability of LFS·LFB structures in the air.•LFP and LFB can enhance the electronic/Li+ transport efficiency and cycling retention. Although Li2FeSiO4 has the theoretical possibility to de-intercalate reversibly two Li+ from its structure (ca. 332 mAh g−1), the slow electronic/Li+ transports and poor capacity retention severely limit its potential application in advanced lithium ion batteries. Herein, to address such issues, a triple phase (1-x-y) Li2FeSiO4·xLiFeBO3·yLiFePO4 (denoted as (1-x-y) LFS·xLFB·yLFP) hybrid with a nested nanostructure is first synthesized through an in-situ sol-gel method. Compared with the pristine LFS, 0.92LFS·0.04LFB·0.04LFP exhibits greatly improved electrochemical performance (258.7 mAh g−1, 0.1 C, 1.5–4.8 V, equivalent to 1.56 Li+ intercalation) due to low charge transfer impedance and Li+ diffusion energy barrier. Meanwhile, the participation of LFP avoids the instability of LFS·LFB structures in the air. It also demonstrates that LFP and LFB can enhance the electronic/Li+ transport efficiency and cycling retention, and shed lights on the further searching for suitable dopants for Li-ion batteries.