Direct Observation of Li-Ion Transport Heterogeneity Induced by Nanoscale Phase Separation in Li-rich Cathodes of Solid-State Batteries.

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 Li1.2 Ni0.13 Co0.13 Mn0.54 O2 . Li-ion transport heterogeneity was observed in LLO grains and across the LLO/Li6 PS5 Cl interface, due to the coexistence of the nanoscale Li2 MnO3 and LiNi1/3 Co1/3 Mn1/3 O2 phases. Consequently, the severely constrained activation of Li2 MnO3 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 Li2 MnO3 domain/Li6 PS5 Cl interface. This study could facilitate interface design of high-performance LLO-based ASSLBs.

Aggregation-Morphology-Dependent Electrochemical Performance of Co3O4 Anode Materials for Lithium-Ion Batteries.

The aggregation morphology of anode materials plays a vital role in achieving high performance lithium-ion batteries. Herein, Co3O4 anode materials with different aggregation morphologies were successfully prepared by modulating the morphology of precursors with different cobalt sources by the mild coprecipitation method. The fabricated Co3O4 can be flower-like, spherical, irregular, and urchin-like. Detailed investigation on the electrochemical performance demonstrated that flower-like Co3O4 consisting of nanorods exhibited superior performance. The reversible capacity maintained 910.7 mAh·g-1 at 500 mA·g-1 and 717 mAh·g-1 at 1000 mA·g-1 after 500 cycles. The cyclic stability was greatly enhanced, with a capacity retention rate of 92.7% at 500 mA·g-1 and 78.27% at 1000 mA·g-1 after 500 cycles. Electrochemical performance in long-term storage and high temperature conditions was still excellent. The unique aggregation morphology of flower-like Co3O4 yielded a reduction of charge-transfer resistance and stabilization of electrode structure compared with other aggregation morphologies.

Hierarchical structured Mn2O3 nanomaterials with excellent electrochemical properties for lithium ion batteries.

A series of Mn2O3 nanomaterials with hierarchical porous structures was synthesized using three types of leaves as templates. In addition to their different morphologies, different porous nanostructures were achieved by choosing different leaves. The Mn2O3 nanomaterial prepared by using gingko leaves as a template provides a larger pore volume and a higher Brunauer-Emmett-Teller (BET) surface area. At the same time, this material also displays excellent electrochemical performance, that is, the specific capacities are 1274.6 mA h g-1 after 300 cycles and 381.5 mA h g-1 at current densities of 300 and 3000 mA g-1, respectively.

Good Low-Temperature Properties of Nitrogen-Enriched Porous Carbon as Sulfur Hosts for High-Performance Li-S Batteries.

Despite the increased attention devoted to exploring cathode construction based on various nitrogen-enriched carbon scaffolds at room temperature, the low-temperature behaviors of Li-S cathodes have yet to be studied. Herein, we demonstrate the good low-temperature electrochemical performances of nitrogen-enriched carbon/sulfur composite cathodes. Electrochemical evaluation indicates that a reversible capacity of 368 mAh g(-1) (0.5 C) over 100 cycles is achieved at -20 °C. After returning to 25 °C, a capacity of 620 mAh g(-1) (0.5 C) is achieved over 350 cycles with a low-capacity attenuation rate (0.071% per cycle) and an initial capacity of 1151 mAh g(-1) (0.1C). This positive electrochemical property was speculated to result from the good surface chemistry of the various amine groups in the nitrogen-enriched carbon materials with enhanced polysulfide immobilization.