Sodium‐ion batteries (SIBs) have attracted much attention due to their abundance, easy accessibility, and low cost. All of these advantages make them potential candidates for large‐scale energy storage. The P2‐type layered transition‐metal oxides (NaxTMO2; TM=Mn, Co, Ni, Ti, Fe, V, Cr, and a mixture of multiple elements) exhibit good Na+ ion conductivity and structural stability, which make them an excellent choice for the cathode materials of SIBs. Herein, the structural evolution, anionic redox reaction, some challenges, and recent progress of NaxTMO2 cathodes for SIBs are reviewed and summarized. Moreover, a detailed understanding of the relationship of chemical components, structures, phase compositions, and electrochemical performance is presented. This Review aims to provide a reference for the development of P2‐type layered transition‐metal oxide cathode materials for SIBs.
Nanorod-like Ni-rich LiNi0.6Co0.2Mn0.2O2 possesses more exposed active {010} facets and the volume change of lithiation/delithiation is as small as 2.12%.
The obstacles of dendrite growth, hydrogen evolution, corrosion and passivation of the zinc anode seriously restrict the cycling stability of aqueous zinc-ion batteries which possess high safety and low cost.
The pursuit of high-mileage models results in the recurrence of lithium metal batteries (LMBs) to researchers' horizon. However, the lithium (Li) metal anode for LMBs undergoes the uncontrollable formation of Li dendrites and infinite volume change during cycling, impeding its practical application. To overcome these challenges, we developed a metal-organic framework (MOF)-derived pathway to construct lithiophilic three-dimensional (3D) skeleton using different substrates (e.g., carbon cloth (CC) and Cu mesh) for dendrite-free lithium metal anodes. As a typical example, the MOF-derived ZnO/nitrogen-doped carbon (NC) nanosheet-modified 3D CC was well-constructed as a lithiophilic hierarchical host (CC@ZnO/NC@Li) for molten Li infiltration. Benefiting from the lithiophilic N-functional groups and LiZn alloy, the synthesized CC@ZnO/NC@Li composite anode promoted the uniform distribution of Li, resulting in a dendrite-free morphology. Meanwhile, the 3D conductive carbon skeleton enhanced the reaction kinetics and buffered the volume change of the electrode. The CC@ZnO/ NC@Li composite anode presented a prolonged lifespan of over 1000 cycles at 5 mA cm −2 with a low overpotential of 19 mV. Coupled with a LiFePO 4 cathode, the CC@ZnO/ NC@Li composite anode also exhibited superior electrochemical properties in the full-cell system. This versatile strategy may open up the channel of designing multi-functional lithiophilic 3D hosts for the Li metal anode.
Nowadays, the rapid development of portable electronic products and low‐emission electric vehicles is putting forward higher requirements for energy‐storage systems. Lithium–sulfur (Li–S) batteries with an ultrahigh energy density (2500 Wh kg−1) are considered the most promising candidates for next‐generation rechargeable batteries. However, the low conductivity of sulfur, the shuttle effect of lithium polysulfide (LPS), and inadequate safety caused by lithium dendrite formation limit their practical applications. In the research of Li–S batteries, it is observed that the surface/interface structure and chemistry of sulfur host materials play significant roles in the performance of Li–S batteries. The reason is that the adsorption/conversion of LPS mainly occurs on the surface/interface of host materials. The functional hosts are used to prevent the polysulfide shuttle or catalyze Li–S conversion reactions (enhance the reaction kinetics), and density functional theory (DFT) is used to understand the mechanism of the interaction between host and polysulfides. Herein, the surface/interface structure and chemistry of sulfur host materials involving structural factors and adsorption/conversion mechanisms of LPS (based on DFT calculation) on the interface are demonstrated. Finally, the remaining challenges, such as the fundamental studies and commercialized applications, as well as the future research directions are discussed.
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