Build a High‐Performance All‐Solid‐State Lithium Battery through Introducing Competitive Coordination Induction Effect in Polymer‐Based Electrolyte

We propose a new concept of competitive coordination induction effects (CCIE) and reveal the essential correlation between the local coordination structure and the interfacial chemistry in PEO-based PICE. The intrinsic mechanism of CCIE and its effects on both the Li⁺ conductivity and the interfacial stability at RT were clarified. The assembled all-solid-state batteries without adding interfacial wetting agent exhibit outstanding rate capability and cycling performance at 30 °C.

Abstract

Polymer-inorganic composite electrolytes (PICE) have attracted tremendous attention in all-solid-state lithium batteries (ASSLBs) due to facile processability. However, the poor Li⁺ conductivity at room temperature (RT) and interfacial instability severely hamper the practical application. Herein, we propose a concept of competitive coordination induction effects (CCIE) and reveal the essential correlation between the local coordination structure and the interfacial chemistry in PEO-based PICE. CCIE introduction greatly enhances the ionic conductivity and electrochemical performances of ASSLBs at 30 °C. Owing to the competitive coordination (Cs^+… TFSI^−… Li⁺, Cs^+… C−O−C ^… Li⁺ and 2,4,6-TFA ^… Li ^… TFSI⁻) from the competitive cation (Cs⁺ from CsPF₆) and molecule (2,4,6-TFA: 2,4,6-trifluoroaniline), a multimodal weak coordination environment of Li⁺ is constructed enabling a high efficient Li⁺ migration at 30 °C (Li⁺ conductivity: 6.25×10⁻⁴ S cm⁻¹; t_Li ⁺ =0.61). Since Cs⁺ tends to be enriched at the interface, TFSI⁻ and PF₆ ⁻ in situ form LiF-Li₃N-Li₂O-Li₂S enriched solid electrolyte interface with electrostatic shielding effects. The assembled ASSLBs without adding interfacial wetting agent exhibit outstanding rate capability (LiFePO_4: 147.44 mAh g⁻¹@1 C and 107.41mAhg⁻¹@2 C) and cycling stability at 30 °C (LiFePO₄:94.65 %@200cycles@0.5 C; LiNi_0.5Co_0.2Mn_0.3O₂: 94.31 %@200 cycles@0.3 C). This work proposes a concept of CCIE and reveals its mechanism in designing PICE with high ionic conductivity as well as high interfacial compatibility at near RT for high-performance ASSLBs.

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