Manipulating Charge‐Transfer Kinetics of Lithium‐Rich Layered Oxide Cathodes in Halide All‐Solid‐State Batteries

Abstract

SSEs based on sulfides, [2] oxides, [3] halides, [4] and borohydrides [5] have been developed over the past decades, including those demonstrating high ionic conductivity (e.g., 12 mS cm −1 for Li 10 GeP 2 S 12 , LGPS, and 25 mS cm −1 for Li 9.54 Si 1.74 P 1.44 S 11.7 Cl l0.3 , LSPSCl), [2] highvoltage stability (e.g., 4.21 V versus Li + / Li for Li 3 YCl 6 , LYC, and 4.3 V versus Li + / Li for Li 3 InCl 6 , LIC), [6] low cost (Li 2 ZrCl 6 and Li 2.25 Zr 0.75 Fe 0.25 Cl 6 ), [7] and appropriate mechanical properties. [8] With these advances in SSEs, various cathode materials have been attempted in ASSBs, such as LiCoO 2 (LCO), [9] LiNi 0.5 Mn 0.3 Co 0.2 O 2 (NMC532), [10] and Ni-rich layered cathode materials (e.g., LiNi 0.8 Mn 0.1 Co 0.1 O 2 , NMC811, [4c] LiNi 0.85 Co 0.1 Mn 0.05 O 2 ,Ni85, [11] and LiNi 0.90 Co 0.05 Mn 0.05 O 2 , Ni90 [12] ). These cathode materials typically show a specific capacity of <200 mAh g −1 , [13] which limits the energy density of ASSBs to less than 450 Wh kg −1 . [14] Comparatively, lithium-rich layered oxide (LLO) possesses a higher theoretical capacity of ≥250 mAh g −1 , [15] and is thus a promising candidate for achieving ASSBs with an energy density of 500 Wh kg −1 Employing lithium-rich layered oxide (LLO) as the cathode of all-solid-state batteries (ASSBs) is highly desired for realizing high energy density. However, the poor kinetics of LLO, caused by its low electronic conductivity and significant oxygen-redox-induced structural degradation, has impeded its application in ASSBs. Here, the charge transfer kinetics of LLO is enhanced by constructing high-efficiency electron transport networks within solidstate electrodes, which considerably minimizes electron transfer resistance. In addition, an infusion-plus-coating strategy is introduced to stabilize the lattice oxygen of LLO, successfully suppressing the interfacial oxidation of solid electrolyte (Li 3 InCl 6 ) and structural degradation of LLO. As a result, LLO-based ASSBs exhibit a high discharge capacity of 230.7 mAh g −1 at 0.1 C and ultra-long cycle stability over 400 cycles. This work provides an in-depth understanding of the kinetics of LLO in solid-state electrodes, and affords a practically feasible strategy to obtain high-energy-density ASSBs.

Role of Substitution Elements in Enhancing the Structural Stability of Li-Rich Layered Cathodes

“…To further explore the mechanism of local structural coordination environment changes exactly, Fourier transform (FT) of the extended X-ray absorption fine structure (EXAFS) was applied to analyze the variation trend of the coordination number at the OCV state and fully charged (4.8 V) state, shown in Figure a, and the fitting details are listed in Figures S9 and S10. The intensity of the signal is related to the coordination number of the central atom, and the corresponding position mainly refers to the bond length of the TM–O and TM–TM interactions . Evidently, the intensity of Ni signals decreases both in the first and second coordination spheres after charging, demonstrating that partial Ni ions would slip to the AM layer and generate a disordered (rock salt) phase, thereby causing the decrease of the long-range order degree.…”

Halide solid-state electrolytes for all-solid-state batteries: structural design, synthesis, environmental stability, interface optimization and challenges

“…Aer solving the interface problem with the Li metal anode, halide-based ASSBs always showed excellent electrochemical performance. 156,161,162 The satisfactory capacity and rate performance of ASSLBs with halide SSEs and high voltage Li-enriched oxide cathode materials are summarized in Table 2.…”

Recent advances in lithium-rich manganese-based cathodes for high energy density lithium-ion batteries

“…The prepared SSBs with the improved LRMO cathode have a capacity of 230.7 mA h g −1 at 0.1C as well as long cycling stability over 400 cycles. 257 But the LRMO/Li 3 InCl 6 interface was severely damaged by the phase transition and reactive oxygen species released by LRMO. To solve this problem, Li et al introduced a uniform LiNbO 3 coating.…”