Search

Given the merits of affordable cost, superior low‐temperature performance, and advanced safe properties, sodium‐ion batteries (SIBs) have exhibited great development potential in large scale energy storage applications. Among various emerging carbonaceous anode materials applied for SIBs, hard carbon (HC) has recently gained significant attention regarding their relatively low cost, wide availability, and optimal overall performance. However, the insufficient initial Coulombic efficiency (ICE) of HC is the main bottlenecks, which is inevitably hindering their further commercial applications. Herein, an in‐depth holistic exposition about the reasons causing the unsatisfied ICE and the recent advances on effective improvement strategies are comprehensively summarized in this review, which have been divided into two aspects including the intrinsic property (degree of graphitization, pore structure, defect, et al.) and the extrinsic factor (electrolyte, electrode materials, et al.). In addition, future prospects and perspectives on HC to enable practical application in SIBs are also briefly outlined. [ABSTRACT FROM AUTHOR]

Sodium (Na) metal anodes are promising candidates for various batteries with high energy density and high‐power density, however, the dendrite growth of Na metal is impeding their practical applications. The binary alloy Na–K is in the liquid state at room temperature with a wide composition range, which renders it inherently free from solid dendrite growth. Whereas the application of Na–K alloy is plagued by the lack of a wettable matrix to immobilize the liquid metal. Herein, a facile method is reported to introduce oxygen‐rich functional groups into carbon fiber cloth (O‐CFC), which is initially Na–K phobic yet turns into superwetting after the treatment. The superwetting behavior of the O‐CFC can be attributed to the favorable enthalpy changes as a result of the introduction of O‐rich functional groups. The superwetting property of the O‐CFC exhibits good universality, which can be extended to melting Na and K metals. By adopting the superwetting O‐CFC as a host for liquid Na–K alloy, the liquid metal can be well retained in the matrix and deliver a stable cycling for >1600 h. The concept of enthalpy‐driven wettability regulation can be enlightening for the host material design of other liquid metals and alloys. [ABSTRACT FROM AUTHOR]

Sodium dual‐ion batteries (Na‐DIBs) have attracted increasing attention due to their high operative voltages and low‐cost raw materials. However, the practical applications of Na‐DIBs are still hindered by the issues, such as low capacity and poor Coulombic efficiency, which is highly correlated with the compatibility between electrode and electrolyte but rarely investigated. Herein, fluoroethylene carbonate (FEC) is introduced into the electrolyte to regulate cation/anion solvation structure and the stability of cathode/anode‐electrolyte interphase of Na‐DIBs. The FEC modulates the environment of PF6− solvation sheath and facilitates the interaction of PF6− on graphite. In addition, the NaF‐rich interphase caused by the preferential decomposition of FEC effectively inhibits side reactions and pulverization of anodes with the electrolyte. Consequently, Sb||graphite full cells in FEC‐containing electrolyte achieve an improved capacity, cycling stability and Coulombic efficiency. This work elucidates the underlying mechanism of bifunctional FEC and provides an alternative strategy of building high‐performance dual ion batteries. [ABSTRACT FROM AUTHOR]

Sodium‐ion batteries (SIBs) present great appeal in various energy storage systems, especifically for stationary grid storage, on account of the abundance of sources and low cost. Unfortunately, the commercialization of SIBs is mainly limited by available electrode materials, especially for the cathodes. Prussian blue analogs (PBAs), emerge as a promising alternative for their structural feasibility in the application of SIBs. Decreasing the defects (vacancies and coordinated water) is an effective strategy to achieve superior electrochemical performance during the synthetic processes. Herein, we summarize crystal structures, synthetic methods, electrochemical mechanisms, and the influences of synthesis conditions of PBAs in detail. This comprehensive overview on the current research progresses of PBAs will give guides and directions to solve the existing problems for their application in SIBs. [ABSTRACT FROM AUTHOR]

High‐voltage lithium‐ion batteries (LIBs) have attracted great attention due to their promising high energy density. However, severe capacity degradation is witnessed, which originated from the incompatible and unstable electrolyte‐electrode interphase at high voltage. Herein, a robust additive‐induced sulfur‐rich interphase is constructed by introducing an additive with ultrahigh S‐content (34.04 %, methylene methyl disulfonate, MMDS) in 4.6 V LiNi0.5Co0.2Mn0.3O2 (NCM523)||graphite pouch cell. The MMDS does not directly participate the inner Li+ sheath, but the strong interactions between MMDS and PF6− anions promote the preferential decomposition of MMDS and broaden the oxidation stability, facilitating the formation of an ultrathin but robust sulfur‐rich interfacial layer. The electrolyte consumption, gas production, phase transformation and dissolution of transition metal ions were effectively inhibited. As expected, the 4.6 V NCM523||graphite pouch cell delivers a high capacity retention of 87.99 % even after 800 cycles. This work shares new insight into the sulfur‐rich additive‐induced electrolyte‐electrode interphase for stable high‐voltage LIBs. [ABSTRACT FROM AUTHOR]

Prussian blue analogues (PBAs) have been regarded as promising cathode materials for alkali‐ion batteries owing to their high theoretical energy density and low cost. However, the high water and vacancy content of PBAs lower their energy density and bring safety issues, impeding their large‐scale application. Herein, a facile "potassium‐ions assisted" strategy is proposed to synthesize highly crystallized PBAs. By manipulating the dominant crystal plane and suppressing vacancies, the as‐prepared PBAs exhibit increased redox potential resulting in high energy density up to ≈450 Wh kg−1, which is at the same level of the well‐known LiFePO4 cathodes for lithium‐ion batteries. Remarkably, unconventional highly‐reversible phase evolution and redox‐active pairs were identified by multiple in situ techniques for the first time. The preferred guest‐ion storage sites and migration mechanism were systematically analysed through theoretical calculations. We believe these results could inspire the design of safe with high energy density. [ABSTRACT FROM AUTHOR]