Solid polymer electrolytes (SPEs) based all-solid-state batteries (ASSBs) have attracted extensive attention as a promising candidate for next-generation energy storage systems. Typical ASSBs require high fabrication pressure to achieve high areal capacity, under which, however, SPEs struggle and risk damage or failure due to their low mechanical strength. There is also a lack of study on complex stress and strain SPEs experience during ASSB cell assembly processes. Here, ceramic solid electrolytes are selected as interlayers to address the stress–strain conditions during assembling. As a result, high areal capacity ASSBs with a LiCoO₂ loading of 12 mg·cm⁻² were assembled with SPE-based composite electrolytes. Around 200 cycles were carried out for these cells at a current density of 1 mA·cm⁻² under room temperature. The capacity decay of the battery at 200 cycles is observed to be as low as 0.06% per cycle. This work identifies a critical issue for application of SPEs in ASSBs and provides a potential strategy for the design of SPE-based ASSBs with high specific energy and long cycle life.

As one of the most promising cathodes for sodium-ion batteries (SIBs), the layered transition metal oxides have attracted great attentions due to their high specific capacities and facile synthesis. However, their applications are still hindered by the problems of poor moisture stability and sluggish Na⁺ diffusion caused by intrinsic structural Jahn–Teller distortion. Herein, we demonstrate a new approach to settle the above issues through introducing K⁺ into the structures of Ni/Mn-based materials. The physicochemical characterizations reveal that K⁺ induces atomic surface reorganization to form the birnessite-type K₂Mn₄O₈. Combining with the phosphate, the mixed coating layer protects the cathodes from moisture and hinders metal dissolution into the electrolyte effectively. Simultaneously, K⁺ substitution at Na site in the bulk structure can not only widen the lattice-spacing for favoring Na⁺ diffusion, but also work as the rivet to restrain the grain crack upon cycling. The as achieved K⁺-decorated P2-Na_0.67Mn_0.75Ni_0.25O₂ (NKMNO@KM/KP) cathodes are tested in both coin cell and pouch cell configurations using Na metal or hard carbon (HC) as anodes. Impressively, the NKMNO@KM/KP||Na half-cell demonstrates a high rate performance of 50 C and outstanding cycling performance of 90.1% capacity retention after 100 cycles at 5 C. Furthermore, the NKMNO@KM/KP||HC full-cell performed a promising energy density of 213.9 Wh·kg⁻¹. This performance significantly outperforms most reported state-of-the-art values. Additionally, by adopting this strategy on O3-NaMn_0.5Ni_0.5O₂, we further proved the universality of this method on layered cathodes for SIBs.

Lithium-sulfur (Li-S) batteries attract sustained attention because of their ultrahigh theoretical energy density of 2567 Wh·kg^–1 and the actual value over 600 Wh·kg^–1. Solid-state Li-S batteries (SSLSBs) emerge in the recent two decades because of the enhanced safety when compared to the liquid system. As for the SSLSBs, except for the difference in the conversion mechanism induced by the cathode materials themselves, the physical-chemical property of solid electrolytes (SEs) also significantly affects their electrochemical behaviors. On account of various reported Li-S batteries, the advantages and disadvantages in performance and the failure mechanism are discussed in this review. Based on the problems of the reported SSLSBs such as lower energy density and faster capacity fading, the strategies of building high-performance SSLSBs are classified. The review aims to afford fundamental understanding on the conversion mechanism of sulfur and engineering design at full-cell level, so as to promote the development of SSLSBs.

Ferroelectric barium titanate nanoparticles (BTO NPs) may play critical roles in miniaturized passive electronic devices such as multi-layered ceramic capacitors. While increasing experimental and theoretical understandings on the structure of BTO and doped BTO have been developed over the past decade, the majority of the investigation was carried out in thin-film materials; therefore, the doping effect on nanoparticles remains unclear. Especially, doping-induced local composition and structure fluctuation across single nanoparticles have yet to be unveiled. In this work, we use electron microscopy-based techniques including high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), integrated differential phase contrast (iDPC)-STEM, and energy dispersive X-ray spectroscopy (EDX) mapping to reveal atomically resolved chemical and crystal structure of BTO and strontium doped BTO nanoparticles. Powder X-ray diffraction (PXRD) results indicate that the increasing strontium doping causes a structural transition from tetragonal to cubic phase, but the microscopic data validate substantial compositional and microstructural inhomogeneities in strontium doped BTO nanoparticles. Our work provides new insights into the structure of doped BTO NPs and will facilitate the materials design for next-generation high-density nano-dielectric devices.