Achieving 766.5 Wh kg<sup>-1</sup> Electrode-Level Energy Density via Solid-State Cathode Integrating Ultrahigh Nickel Oxide and Lithium Iron Chloride.

Wang, Zi-Wei; Xiang, Shun; Luo, Jin-Da; Shi, Zhangqin; Wu, Ye-Chao; Tan, Hao-Yuan; Cheng, Xiaobin; Zhou, Mei-Yu et al. · Nano Lett · 2025

basic_science · Level V

Where this comes from

Abstract

Coupling chloride solid electrolytes (SEs) with ultrahigh-nickel oxide cathodes (LiNi<sub><i>x</i></sub>Co<sub><i>y</i></sub>Mn<sub>1-x-y</sub>O<sub>2</sub>, <i>x</i> > 0.9) exhibits higher interfacial stability and better safety than traditional sulfide SE-based cathodes. However, the inevitable ∼30 wt% addition of inactive chloride SEs for sufficient Li<sup>+</sup> percolation sacrifices the electrode-level energy density. Herein, using ion-conductive and electrochemically active Li<sub>2</sub>FeCl<sub>4</sub> (LFC) to pair ultrahigh-nickel cathode LiNi<sub>0.92</sub>Co<sub>0.05</sub>Mn<sub>0.03</sub>O<sub>2</sub> (Ni92), we fabricate an all-active-cathode Ni92@LFC which unlocks an extra 22% capacity in comparison to Ni92@Li<sub>3</sub>InCl<sub>6</sub>, thus realizing a remarkable electrode energy density of 766.5 Wh kg<sup>-1</sup>. We demonstrate that the lithium-deficient LFC exhibits sufficient ionic conductivity to achieve a higher capacity of Ni92@LFC than Ni92@Li<sub>3</sub>InCl<sub>6</sub> cathode at 3 C (114 mAh g<sup>-1</sup> vs 86 mAh g<sup>-1</sup>). More attractively, we observe an <i>in-situ</i> formed Li<sub><i>x</i></sub>FeOCl interphase with rapid dynamics and high stability, facilitating durable cycling with 83.4% capacity retention after 1000 cycles. Our all-active-cathode design paves the way to higher-energy-density all-solid-state cathodes.