RESUMEN
Silicon (Si) is a promising anode material for high-energy-density lithium-ion batteries, but the significant volume change of Si particles during alloying/dealloying with lithium (Li) undermines the mechanical integrity of Si anode, causing electrode fracture, delamination and rapid capacity decay. Herein, a robust triple crosslinked network (TCN) binder with high ionic conductivity and hierarchical stress dissipation is reported for Si anodes, which is prepared by in situ chemical crosslinking polyacrylic acid (PAA) and melamine (MA). The triple interactions of hydrogen bonds, electrostatic interactions, and covalent amide bonds enhance the adhesion of binder to Si and synergistically promote stress dissipation within Si anodes, thus strengthening the dynamic structural stability of Si anodes during cycling. Moreover, the rapid coupling/decoupling of Li+ with the TCN binder enables an impressive Li+ transference number of 0.63 and high ionic conductivity of 1.2 × 10-4 S cm-1. Consequently, the Si-TCN anode delivers specific capacity of 2268 mAh g-1 with a high mass loading of 2 mg cm-2, high-rate performance of 1673 mAh g-1 at 5 A g-1, and stable cycling for 250 cycles at 1 A g-1, thus showing great prospects for high-energy-density Si-based batteries.
RESUMEN
Lithium (Li) metal is a promising anode for high-energy-density batteries; however, its practical viability is hampered by the unstable metal Li-electrolyte interface and Li dendrite growth. Herein, a mixed ion/electron conductive Li3N-Mo protective interphase with high mechanical stability is designed and demonstrated to stabilize the Li-electrolyte interface for a dendrite-free and ultrahigh-current-density metallic Li anode. The Li3N-Mo interphase is simultaneously formed and homogeneously distributed on the Li metal surface by the surface reaction between molten Li and MoN nanosheets powder. The highly ion-conductive Li3N and abundant Li3N/Mo grain boundaries facilitate fast Li-ion diffusion, while the electrochemically inert metal Mo cluster in the mosaic structure of Li3N-Mo inhibits the long-range crystallinity and regulates the Li-ion flux, further promoting the rate capability of the Li anode. The Li3N-Mo/Li electrode has a stable Li-electrolyte interface as manifested by a low Li overpotential of 12 mV and outstanding plating/stripping cyclability for over 3200 h at 1 mA cm-2. Moreover, the Li3N-Mo/Li anode inhibits Li dendrite formation and exhibits a long cycling life of 840 h even at 30 mA cm-2. The full cell assembled with LiFePO4 cathode exhibits stable cycling performance with 87.9% capacity retention for 200 cycles at 1C (1C = 170 mA g-1) as well as high rate capability of 83.7 mAh g-1 at 3C. The concept of constructing a mixed ion/electron conductive interphase to stabilize the Li-electrolyte interface for high-rate and dendrite-free Li metal anodes offers a viable strategy to develop high-performance Li-metal batteries.
RESUMEN
On the heels of exacerbating environmental concerns and ever-growing global energy demand, development of high-performance renewable energy-storage and -conversion devices has aroused great interest. The electrode materials, which are the critical components in electrochemical energy storage (EES) devices, largely determine the energy-storage properties, and the development of suitable active electrode materials is crucial to achieve efficient and environmentally friendly EES technologies albeit the challenges. Two-dimensional transition-metal chalcogenides (2D TMDs) are promising electrode materials in alkali metal ion batteries and supercapacitors because of ample interlayer space, large specific surface areas, fast ion-transfer kinetics, and large theoretical capacities achieved through intercalation and conversion reactions. However, they generally suffer from low electronic conductivities as well as substantial volume change and irreversible side reactions during the charge/discharge process, which result in poor cycling stability, poor rate performance, and low round-trip efficiency. In this Review, recent advances of 2D TMDs-based electrode materials for alkali metal-ion energy-storage devices with the focus on lithium-ion batteries (LIBs), sodium-ion batteries (SIBs), potassium-ion batteries (PIBs), high-energy lithium-sulfur (Li-S), and lithium-air (Li-O2 ) batteries are described. The challenges and future directions of 2D TMDs-based electrode materials for high-performance LIBs, SIBs, PIBs, Li-S, and Li-O2 batteries as well as emerging alkali metal-ion capacitors are also discussed.