Low-Temperature Synthesis of a Porous High-Entropy Transition-Metal Oxide as an Anode for High-Performance Lithium-Ion Batteries.

Transition-metal oxides (TMOs) are promising anode materials for high-performance lithium-ion batteries (LIBs) because of their abundant reserves and high theoretical capacity. However, the poor conductivity, unstable solid electrolyte interface (SEI) film, and poor cycling stability still limit their practical applications. As a novel kind of anode material, a high-entropy oxide (HEO) is a single-phase crystal structure composed of multiple metal elements, demonstrating a huge potential for energy storage applications due to the synergistic effect of various metal species. Herein, we have designed the porous spinel-phase HEO (Cr0.2Fe0.2Co0.2Ni0.2Zn0.2)3O4 synthesized at low temperature by a sol-gel method. On the one hand, the unique porous nanostructure not only promotes transport of the electrolyte but also alleviates the volume change of active materials upon cycling. On the other hand, the stabilization effect of entropy can suppress the formation of cation short-range order within the crystalline structure of HEO by a lattice distortion effect, thus guaranteeing a fast lithium-ion transport and achieving an excellent electrochemical performance. As a result, the as-prepared HEO-450 electrode delivers 1022 mAh/g after 1000 cycles at 1 A/g and 220 mAh/g at an ultrahigh current density of 30 A/g, respectively.

Lithium-Ion-Engineered Interlayers of V2C MXene as Advanced Host for Flexible Sulfur Cathode with Enhanced Rate Performance.

A flexible free-standing S@lithium-ion-intercalated V2C MXene/rGO-CNT (S@V2C-Li/C) electrode was rationally prepared to address the neglected issue of Li-ion transport for high-rate lithium-sulfur batteries. In this unique nanoarchitecture, rGO and CNTs serve as a flexible skeleton with high conductivity, whereas V2C-Li MXene plays a vital role in both the chemical absorption of polysulfides and the enhanced transport of lithium ions due to its high polarity and enlarged interlayer distance. Benefiting from the synergistic effect of strong chemical absorption capability and fast lithium-ion migration and exchange, the as-prepared S@V2C-Li/C electrode demonstrates long-term cycling stability with small capacity decay rates of 0.053 and 0.051% per cycle over 500 cycles at 1 and 2 C, respectively.