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• A scalable microstructure engineering strategy for developing mechanically reinforced Ni-rich cathodes. • A well-designed polycrystalline Ni-rich cathode consisting of densely packed large-size primary particles. • Superior rate performance (31.7 mAh g−1 at 4C) and cyclic stability (84.1% after 100 cycles at 0.2C). Mechanical integrity is crucial for the intra-particle ionic/electronic transfer in all-solid-state batteries. However, electrode particles suffer severe electrochemo-mechanical degradations during electrode compaction and high-voltage operation, which is extremely true in the popular high-energy cathodes of fragile polycrystalline Ni-rich oxides composed of loosely stacked nanoparticles. Herein, we develop mechanically reinforced polycrystalline Ni-rich cathodes consisting of densely packed large-size primary particles based on a scalable microstructure engineering strategy. The structural characterization and finite element simulation results demonstrate that this well-designed microstructure of cathodes can suppress the stress/strain accumulation and formation of cracks, and thus maintain the original microstructure and highly percolated ionic/electronic networks. All-solid-state batteries based on mechanically reinforced Ni-rich cathodes achieve significantly improved specific capacity, rate capability, and cyclic stability. This work provides a new sight for designing advanced cathodes to boost the development of high-power and long-life all-solid-state batteries. [ABSTRACT FROM AUTHOR]

Traditional heterogeneous polycrystalline layered oxides suffer from serious chemo-mechanical degradations, which is extremely true in nickel-rich cathodes under high-voltage operation. Although single-crystalline structure is proved to be able to withstand anisotropic lattice strain and prevent cracks formation, the long cycle stability at high-voltage in all-solid-state batteries (ASSBs) with nickel-rich layered oxides as the cathode are still far from commercial applications. Herein, we synthesize a micro-sized single-crystalline nickel-rich oxides LiNi 0.83 Co 0.11 Mn 0.06 O 2 (SC–N83) to eliminate the chemo-mechanical failures. The well-dispersed SC-N83 in the ASSBs delivers an excellent cyclic stability under high-voltage (4.4 V vs Li/Li+) operation, which shows a capacity retention of 85.1% after 500 cycles at 0.5C. Even at high active areal loading of 22.6 cm−2 (corresponding to an initial areal capacity of 4.19 mAh cm−2) and high temperature of 50 °C, the SC-N83 cathodes can still maintain 75.5% discharge capacity after 200 cycles at 0.5C. The high cycling stability is further proved to be attributed to dramatically suppressed mechanical failure caused by the build-up of strain and stress. This proposed strategy with highly dispersed single-crystalline nickel-rich oxides paves the way to develop advanced high-capacity and high-voltage operating ASSBs. [Display omitted] • Single-crystalline Ni-rich oxides against chemo-mechanical failure at high voltage. • Long life cathodes (85.1% after 500 cycles at 0.5C) at high voltage operation. • A practical cathode with the areal capacity of 4.19 mAh cm−2 is fabricated. • Excellent fast charge capability (142.9 mAh g−1 at 5 C and 50 °C). [ABSTRACT FROM AUTHOR]