Enable the Domino-Like Structural Recovering in Bismuth Anode to Achieve Fast and Durable Na/K Storages.

Alloying-type anodes show capacity and density advantages for sodium/potassium-ion batteries (SIBs/PIBs), but they encounter serious structural degradation upon cycling, which cannot be resolved through conventional nanostructuring techniques. Herein, we present an in-depth study to reveal the intrinsic reason for the pulverization of bismuth (Bi) materials upon (de)alloying, and report a novel particle-in-bulk architecture with Bi nanospheres inlaid in the bulk carbon (BiNC) to achieve durable Na/K storage. We simulate the volume-expansion-resistant mechanism of Bi during the (de)alloying reaction, and unveil that the irreversible phase transition upon (de)alloying underlies the fundamental origin for the structural degradation of Bi anode, while a proper compressive stress (~10 %) raised by the bulk carbon can trigger a "domino-like" Bi crystal recovering. Consequently, the as obtained BiNC exhibits a record high volumetric capacity (823.1 mAh cm-3 for SIBs, 848.1 mAh cm-3 for PIBs) and initial coulombic efficiency (95.3 % for SIBs, 96.4 % for PIBs), and unprecedented cycling stability (15000 cycles for SIBs with only 0.0015 % degradation per cycle), outperforming the state-of-the-art literature. This work provides new insights on the undesirable structural evolution, and proposes basic guidelines for design of the anti-degradation structure for alloy-type electrode materials.

Co Nanoparticles Embedded in Mesoporous Walls of Carbon Nanoboxes for Rechargeable Zinc-air Batteries.

Design of non-noble metal electrocatalysts with high catalytic activity and stability to replace commercial Pt/C is crucial in the commercialization development of Zn-air batteries (ZABs). In this work, Co catalyst nanoparticles coupled with nitrogen-doped hollow carbon nanoboxes were well designed through zeolite-imidazole framework (ZIF-67) carbonization. As a result, the 3D hollow nanoboxes reduced the charge transport resistance, and the Co nanoparticles loaded on nitrogen-doped carbon supports exhibited excellent electrocatalytic performance for oxygen reduction reaction (ORR, E1/2 =0.823 V vs. RHE), similar to that of commercial Pt/C. Moreover, the designed catalysts showed an excellent peak density of 142 mW cm-2 when applied on ZABs. This work provides a promising strategy for the rational design of non-noble electrocatalysts with high performance for ZABs and fuel cells.

Modulating the Graphitic Domains of Hard Carbons Derived from Mixed Pitch and Resin to Achieve High Rate and Stable Sodium Storage.

Resin derived hard carbons (HCs) generally demonstrate remarkable electrochemical performance for both sodium ion batteries (SIBs) and potassium-ion batteries (KIBs), but their practical applications are hindered by their high price and high temperature pyrolysis (≈1500 °C). Herein, low-cost pitch is coated on the resin surface to compromise the cost, and meanwhile manipulate the microstructure at a relatively low pyrolysis temperature (1000 °C). HC-0.2P-1000 has a large number of short graphitic layer structures and a relatively large interlayer spacing of 0.3743 nm, as well as ≈1 nm sized nanopores suitable for sodium storage. Consequently, the as produced material demonstrates a superior reversible capacity (349.9 mAh g-1 for SIBs and 321.9 mAh g-1 for KIBs) and excellent rate performance (145.1 mAh g-1 at 20 A g-1 for SIBs, 48.5 mAh g-1 at 20 A g-1 for KIBs). Furthermore, when coupled with Na3 V2 (PO4 )3 as cathode, the full cell exhibits a high energy density of 251.1 Wh kg-1 and excellent stability with a capacity retention of 73.3% after 450 cycles at 1 A g-1 .