Electrochemo‐Mechanical Effects on Structural Integrity of Ni‐Rich Cathodes with Different Microstructures in All Solid‐State Batteries

Abstract

The electrochemo‐mechanical effects on the structural integrity of electrode materials during cycling is a non‐negligible factor that affects the cyclability and rate performance of all solid‐state batteries (ASSBs). Herein, combined with in situ electrochemical impedance spectroscopy (EIS), focused ion beam (FIB)–scanning electron microscope (SEM), and solid state nuclear magnetic resonance (ssNMR) techniques, the electrochemical performance and electrochemo‐mechanical behavior are compared of conventional polycrystalline NCM811 (LiNi0.8Co0.1Mn0.1O2), small‐size polycrystalline NCM811 and single‐crystal (S‐) NCM811 in Li10SnP2S12 based ASSBs during long charge–discharge cycles. The results show that the deteriorating performance of both large and small polycrystalline NCM811 originates from their inherent structural instability at >4.15 V, induced by the visible voids between the randomly oriented grains and microcracks due to the electrode pressing process and severe anisotropic volume change during cycling, rather than lithium ion transport in the primary particle. In contrast, S‐NCM811 with good microstructural integrity show remarkably high capacity (187 mAh g−1, 18 mA g−1), stable cyclability (100 cycles, retention of 64.5%), and exceptional rate capability (102 mAh g−1 at 180 mA g−1) in ASSBs even without surface modification. Moreover, 1 wt% LiNbO3@S‐NCM811 further demonstrates excellent initial discharge capacity and capacity retention. This work highlights the critical role of electrochemo‐mechanical integrity and offers an promising path towards mechanically‐reliable cathode materials for ASSBs.

High Energy Density Single-Crystal NMC/Li6PS5Cl Cathodes for All-Solid-State Lithium-Metal Batteries

“…Figure S9c shows that the PC-NMC/LPSCl cathodes again had lower discharge capacities that decayed faster (92.4% after 50 cycles), due to their higher defect density and accelerated particle pulverization. 15 …”

“… 12 − 14 Liu et al investigated a SC LiNi 0.8 Mn 0.1 Co 0.1 O 2 /Li 10 SnP 2 S 12 /Li 4 Ti 5 O 12 ASSB that delivered a maximum discharge capacity of 187 mA h g –1 under a stack pressure of 25 MPa. 15 Although the cycling performance of the SC-NMC-based cathode was superior to a PC-NMC-based counterpart, the coulombic efficiency (CE) of the first cycle was only 74% and significantly lower than a conventional LIB equivalent (89%).…”

High Energy Density Single Crystal NMC/Li6PS5Cl Cathodes for All-Solid-State Lithium Metal Batteries

“…1 ASSB that delivered a maximum discharge capacity of 187 mA h g −1 under a stack pressure of 25 MPa. 15 Although the cycling performance of the SC-NMC-based cathode was superior to a PC-NMC-based counterpart, the coulombic efficiency (CE) of the first cycle was only 74% and significantly lower than a conventional LIB equivalent (89%).…”

State of the Art in Crystallization of LiNbO3 and Their Applications

“…Surface modification of high voltage cathodes is important method to improve electrochemical performance of Li-ion battery [67][68][69]. LiNbO 3 -coating has been found to be a useful strategy to improve stability of electrode materials [68,69].…”