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Ferroelectrics can significantly boost electrochemical performances of all‐solid‐state batteries by constructing built‐in electric field to reduce the space charge layer at cathode/solid‐state electrolyte interface. However, the construction mechanism of ferroelectric built‐in electric field is poorly understood. Herein, the guanidinium perchlorate (GClO4) ferroelectrics as the cathode coatings in the LiCoO2‐based all‐solid‐state lithium battery are reported, which has state‐of‐the‐art specific capacity of 210.6 mAh g−1 (91.6% of the liquid battery). Systematic studies reveal that the flexoelectric effect originating from the lattice mismatch between GClO4 and LiCoO2 gives GClO4 coatings the single‐domain state and upward self‐polarization. Consequently, a vertically downward built‐in electric field is generated relative to the cathode, which transports the lithium ions inside the electrolyte to the three‐phase interface to alleviate the space charge layer. These findings highlight that the microstructural characteristics of ferroelectric and electrode materials are the primary concern for building an effective built‐in electric field. [ABSTRACT FROM AUTHOR]

Li‐rich layered oxide (LLO) cathode materials with high specific capacities could significantly enhance the energy density of all‐solid‐state lithium batteries (ASSLBs). However, the specific practical capacities of LLO materials in ASSLBs are extremely low due to poor initial activation. Here, scanning transmission electron microscopy with in situ differential phase contrast imaging was first used to study the initial activation mechanism of Li1.2Ni0.13Co0.13Mn0.54O2. Li‐ion transport heterogeneity was observed in LLO grains and across the LLO/Li6PS5Cl interface, due to the coexistence of the nanoscale Li2MnO3 and LiNi1/3Co1/3Mn1/3O2 phases. Consequently, the severely constrained activation of Li2MnO3 during the first charging could be attributed to a nanoscale phase separation in LLO, hindering Li‐ion transport through its particles, and causing high impedance in the Li2MnO3 domain/Li6PS5Cl interface. This study could facilitate interface design of high‐performance LLO‐based ASSLBs. [ABSTRACT FROM AUTHOR]

Herein, the boron-doped Li-rich materials are prepared by rapid nucleation-assisted solvothermal and high-temperature method. In this work, the effects of boron doping on crystal structure and cycling performances of as-prepared materials were investigated. The material characterization results show that the introduction of B reduces the TM valence, enlarges the (003) space distance, and modulates the local crystal structure, which may change the electrochemical performance of as-prepared samples. Li 1.2 Ni 0.24 Co 0.08 Mn 0.48 B 0.02 O 2 (LLNCMBO-2) showed an increase in discharge capacity of 36.5 mAh g−1 at 0.1 C compared to the pristine sample. The LLNCMBO-2 exhibit high capacity retention of 85.50 % after 200 cycles with a voltage decay of only 254.9 mV. Additionally, the results of wide temperature testing show that the electrochemical performance of boron-doped samples improved evidently. • A route of structural modulation by B-doping modification is reported. • The effect of B doping on oxygen vacancies and oxygen stability are revealed. • The LLNCMBO-2 exhibit excellent electrochemical performance under wide temperature. [ABSTRACT FROM AUTHOR]

High voltage spinel LiNi 0.5 Mn 1.5 O 4 (LNMO) cathode materials with well-developed polyhedral-shape structure have been successfully synthesized via a rapid hydrothermal process followed by high-temperature calcination with Li source. The as-synthesized samples were characterized by powder X-ray diffraction, Raman spectroscopy, Scanning electron microscopy and electrochemical test. All samples show polyhedral-shape morphologies as well as cubic spinel structure with Fd3m space group. Electrochemical analysis verifies that the spinel LNMO cathode prepared with sulfate at hydrothermal temperature of 200 °C exhibits the better electrochemical properties in terms of discharge capacity, cycling stability and rate performance. This sample delivers an initial discharge capacity of 131.1 mAh g −1 at 0.5 C rate at 25 °C, with the capacity retention of 85.2% after 100 charge-discharge cycles. Additionally, it still shows high rate performance with a discharge capacity of 110.9 mAh g −1 even at 20 C rate. The excellent electrochemical properties are mainly attributed to its high crystallinity, appropriate particle size and uniform particle size distribution. These results suggest that the rapid hydrothermal and post-calcination method is an effective way for preparing high voltage LNMO cathode materials which can be applied to lithium ion batteries. [ABSTRACT FROM AUTHOR]

Tuning the anionic redox is an effective strategy to improve the electrochemical performance of the Li-rich materials. Here, the Li-rich material, 0.5Li 2 MnO 3 ·0.5LiNi 0.8 Co 0.1 Mn 0.1 O 2 (LR-811), was prepared by the nucleation and post-solvothermal method with high temperature calcination. Compared with the well-known Li-rich material, 0.5Li 2 MnO 3 ·0.5LiNi 1/3 Co 1/3 Mn 1/3 O 2 (LR-111), the LR-811 shows excellent cycling performance due to the Ni ions can improve the structural stability and mitigate the oxygen redox during charge/discharge processes at 25 °C. At the same time, wide-temperature range operation of LR-811 sample are also investigated, the results showed that the layered-to-spinel transition and rapid capacity decay became more serious at 55 °C, the reason for this is that the elevated operation temperature facilitates the dissolution of TM ions and the decomposition of the electrolyte. These insights will help us seek electrode modification methods and find suitable electrolyte to improve the wide temperature application of the LR-811 material. • The performance of 0.5Li 2 MnO 3 ·0.5LiNi 0.8 Co 0.1 Mn 0.1 O 2 (LR-811) was modulated by cation arrangement. • The LR-811 displays excellent electrochemical performance at 25 °C. • The LR-811 still undergoes phase transformation from layered into spinel-like structure at 55 °C. [ABSTRACT FROM AUTHOR]

A series of LiNi 0.5 Mn 1.5 O 4 cathode samples with different morphologies was synthesized via a template method and facile post-calcination process. Rod-like and truncated octahedral particles with {111} surface are obtained through increasing the calcination temperature. The exposed surface of as-prepared materials is mainly detected by SEM and TEM images. Detailed characterization of electrochemical performance of samples reflects that the T-775 cathode sample displays superior rate capability, and the discharge capacity reaches 108.2 mAh g−1 at 100C. The energy density of full cells, T-775 sample as the cathode material and commercial graphite as the anode material, retain 534.9 Wh kg−1 after 100 cycles. These improvements might be due to the synergistic effect of the {111} surface and smaller particle sizes, which improves interfacial stability and reduces the diffusion distance of Li+ during the interaction/deinteraction process. • LiNi 0.5 Mn 1.5 O 4 sample was synthesized via a facile calcination process. • T-775 sample, which was prepared at 775 °C, displays outstanding rate capability. • The energy density of full cells retain 534.9 wh kg−1 after 100 cycles. [ABSTRACT FROM AUTHOR]