Enhancing the electrochemical performances of Li7P3S11 electrolyte through P2O5 substitution for all-solid-state lithium battery

• Published in: Solid state ionics 2020-12, Vol.358, p.115506, Article 115506
• Main Authors: Guo, Yayu, Guan, Huilan, Peng, Wenxiu, Li, Xuelei, Ma, Yue, Song, Dawei, Zhang, Hongzhou, Li, Chunliang, Zhang, Lianqi
• Format: Article
• Language: English
• Subjects: All-solid-state lithium batteries; Li7P3S11; LiCoO2; P2O5 substitution; Sulfide electrolyte
• ISSN: 0167-2738; 1872-7689
• DOI: 10.1016/j.ssi.2020.115506

Li7P3S11 (70Li2S·30P2S5) sulfide is a promising electrolyte candidate for all-solid-state lithium batteries (ASSLBs) owing to its high ionic conducivity and wide electrochemical stability window. However, the sensitivity to moisture and the poor interfacial compatibility with electrodes limit the conventional application of Li7P3S11. Herein, we present a substitution strategy to produce a O-incorporated 70Li2S·(30-x)P2S5·xP2O5 (mol%) sulfide electrolyte to address above issues. The elaborately designed electrolyte is prepared via wet vibration ball milling technique with P2O5 substitution content of 1, 3 and 5. As a result, the 70Li2S·27P2S5·3P2O5 electrolyte displays the highest ionic conductivity of 2.61× 10−3 S cm−1 which outperforms than that of pristine Li7P3S11 (ionic conductivity of 1.35 × 10−3 S cm−1) and the assembled LiCoO2@LiNbO3/70Li2S·27P2S5·3P2O5/Li-In ASSLB exhibits the superior capacity retention of 93.2% after 100 cycles at 0.5C. The reason for the developed electrochemical performance lies in the substitution of the non-bridging sulfur atom with bridging oxygen atom, from which the interaction between electrolyte and lithium ions is weakened, thereby the rapid transfer of lithium ions is facilitated. Furthermore, Raman and XRD results indicate that the adverse interfacial reactions are suppressed through P2O5 substitution. This work suggests that P2O5 substitution is an effective strategy for sulfide electrolyte toward high energy all-solid-state lithium batteries. [Display omitted] •Ionic conductivity of 70Li2S·30P2S5 is improved by 3 mol% P2O5 substitution for P2S5.•Electrochemical performance of LiCoO2@LiNbO3 all-solid-state lithium batteries is improved.•The presence of O dopant is conducive to improve the chemical stability of 70Li2S·30P2S5 electrolyte.