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.

Critical Role of Aromatic C(sp2)-H in Boosting Lithium-Ion Storage.

Exploring high-sloping-capacity carbons is of great significance in the development of high-power lithium-ion batteries/capacitors (LIBs/LICs). Herein, an ion-catalyzed self-template method is utilized to synthesize the hydrogen-rich carbon nanoribbon (HCNR), achieving high specific and rate capacity (1144.2/471.8 mAh g-1 at 0.1/2.5 A g-1). The Li+ storage mechanism of the HCNR is elucidated by in situ spectroscopic techniques. Intriguingly, the protonated aromatic sp2-hybridized carbon (C(sp2)-H) can provide additional active sites for Li+ uptake via reversible rehybridization to sp3-C, which is the origin of the high sloping capacity. The presence of this sloping feature suggests a highly capacitance-dominated storage process, characterized by rapid kinetics that facilitates superior rate performance. For practical usage, the HCNR-based LIC device can deliver high energy/power densities of 198.3 Wh kg-1/17.9 kW kg-1. This work offers mechanistic insights on the crucial role of aromatic C(sp2)-H in boosting Li+ storage and opens up new avenues to develop such sloping-type carbons for high-performance rechargeable batteries/capacitors.

Kinetic Analysis of Bio-oil Derived Hierarchically Porous Carbon for Superior Li+/Na+ Storage.

Herein, an efficient biomass utilization is proposed to prepare bio-oil-derived carbon (BODPC) with hierarchical pores and certain H/O/N functionalities for superior Li+/Na+ storage. Kinetic analyses reveal that BODPC has similar behavior in the electrochemical Li+ and Na+ storage processes, in terms of physical adsorption (Stage I), chemical redox reactions with surface functionalities (Stage II), and insertion into the graphitic interlayer (Stage III). Promisingly, BODPC exhibits a high reversible specific capacity (1881.7 mAh g-1 for Li+ and 461.0 mAh g-1 for Na+ at 0.1 A g-1), superior rate capability (674.1 mAh g-1 for Li+ and 125.7 mAh g-1 for Na+ at 5.0 A g-1), and long-term cyclability. More notably, the BODPC with highly capacitive-dominant behavior would hold great promise for the applications of high-power, durable, and safe rechargeable batteries/capacitors.

Operando mechanistic and dynamic studies of N/P co-doped hard carbon nanofibers for efficient sodium storage.

In situ Raman and electrochemical results reveal that Na+ adsorbs on the surface/defective sites of N/P-HCNF and inserts randomly into its turbostratic nanodomains in the dilute state without a staged formation, which can facilitate fast Na+ diffusion kinetics for efficient sodium storage.

Oxygen vacancies boosted the electrochemical kinetics of Nb2O5-x for superior lithium storage.

The introduction of oxygen vacancies (OVs) into Nb2O5 can not only provide more active sites for lithium storage but also change the electronic structure of Nb2O5 to boost electron/ion transport kinetics. Consequently, the defective Nb2O5-x exhibits high lithium storage capacity, superior rate capability, and cycling stability.

Porous α-Fe2O3 nanoparticles encapsulated within reduced graphene oxide as superior anode for lithium-ion battery.

A facile route for the controllable synthesis of porous α-Fe2O3 supported by three-dimensional reduced graphene oxide (rGO) is presented. The synergistic effect between α-Fe2O3 and rGO can increase the electrolyte infiltration and improve lithium ion diffusion as well. Moreover, the combination of rGO nanosheets can increase the available surface area to provide more active sites and prevent α-Fe2O3 nanoparticles from agglomeration during the cycling process to ensure its long-term cycle performance. Consequently, the α-Fe2O3/rGO nanocomposites exhibit higher reversible specific capacity (1418.2 mAh g-1 at 0.1 A g-1), better rate capability (kept 804.5 mAh g-1 at 5.0 A g-1) and cycling stability than the α-Fe2O3 nanoparticles. Owing to the superior electrochemical performance, the α-Fe2O3/rGO nanocomposites might have a great potential as anode for lithium-ion batteries.