Search

The cycling stability of O3‐type NaNi1/3Fe1/3Mn1/3O2 (NFM) as a commercial cathode material for sodium ion batteries (SIBs) is still a challenge. In this study, the Ni/Fe/Mn elements are replaced successfully with tantalum (Ta) in the NFM lattice, which generated additional delocalized electrons and enhanced the binding ability between the transition metal and oxygen, resulting in suppressed lattice distortion during charging and discharging. This caused significant mitigation of voltage decay and improved cycle stability within the potential range of 2.0–4.2 V. The optimized Na(Ni1/3Fe1/3Mn1/3)0.97Ta0.03O2 sample achieved a reversible capacity of 162.6 mAh g−1 at a current rate of 0.1 C and 73.2 mAh g−1 at a high rate of 10 C. Additionally, the average charge/discharge potential retention reached 98% after 100 cycles, significantly mitigating the voltage decay. This work demonstrates a significant contribution towards the practical utilization of NFM cathodes in the SIBs energy storage field. [ABSTRACT FROM AUTHOR]

Lithium‐ion batteries with spinel Li4Ti5O12 materials as anode, which can offer fast charge times, high power output, superior safety, and long life, are considered to be a competitive choice for grid‐scale energy storage systems (ESS). Herein, a 10 Ah lithium–titanate battery with lithium cobalt oxide–lithium nickel cobalt manganese oxide dual‐phase cathode is developed and its application in 100 kWh‐level ESS is investigated. The 10 Ah single battery demonstrates a specific capacity of 79 Wh kg−1 with a high‐capacity retention rate of 91.8% after 1000 cycles at 55 °C and >80% capacity retention at 15 Ccell. The 125 kWh ESS shows an energy efficiency of 97.82% and 89.97% at 0.2 and 1.5 CSystem, respectively. Self‐discharge and constant power tests indicate that the battery system is stable, thus suitable for storing intermittent power from renewable sources such as solar and wind. The system's ability of smoothing the fluctuated power is confirmed by coordinating with a wind power system. [ABSTRACT FROM AUTHOR]

Rechargeable batteries based on multivalent cation (Mvn+, n>1) carriers are considered potentially low‐cost alternatives to lithium‐ion batteries. However, the high charge‐density Mvn+ carriers generally lead to sluggish kinetics and poor structural stability in cathode materials. Herein, we report an Mvn+ storage via intercalation pseudocapacitance mechanism in a 2D bivalve‐like organic framework featured with localized ligands. By switching from conventional intercalation to localized ligand‐assisted‐intercalation pseudocapacitance, the organic cathode exhibits unprecedented fast kinetics with little structural change upon intercalation. It thus enables an excellent power density of 57 kW kg−1 over 20000 cycles for Ca2+ storage and a power density of 14 kW kg−1 with a long cycling life over 45000 cycles for Zn2+ storage. This work may provide a largely unexploited route toward constructing a local dynamic coordination microstructure for ultrafast Mvn+ storage. [ABSTRACT FROM AUTHOR]

As one of the most promising cathodes for sodium-ion batteries (SIBs), the layered transition metal oxides have attracted great attentions due to their high specific capacities and facile synthesis. However, their applications are still hindered by the problems of poor moisture stability and sluggish Na+ diffusion caused by intrinsic structural Jahn—Teller distortion. Herein, we demonstrate a new approach to settle the above issues through introducing K+ into the structures of Ni/Mn-based materials. The physicochemical characterizations reveal that K+ induces atomic surface reorganization to form the birnessite-type K2Mn4O8. Combining with the phosphate, the mixed coating layer protects the cathodes from moisture and hinders metal dissolution into the electrolyte effectively. Simultaneously, K+ substitution at Na site in the bulk structure can not only widen the lattice-spacing for favoring Na+ diffusion, but also work as the rivet to restrain the grain crack upon cycling. The as achieved K+-decorated P2-Na0.67Mn0.75Ni0.25O2 (NKMNO@KM/KP) cathodes are tested in both coin cell and pouch cell configurations using Na metal or hard carbon (HC) as anodes. Impressively, the NKMNO@KM/KP||Na half-cell demonstrates a high rate performance of 50 C and outstanding cycling performance of 90.1% capacity retention after 100 cycles at 5 C. Furthermore, the NKMNO@KM/KP||HC full-cell performed a promising energy density of 213.9 Whkg−1. This performance significantly outperforms most reported state-of-the-art values. Additionally, by adopting this strategy on O3-NaMn0.5Ni0.5O2, we further proved the universality of this method on layered cathodes for SIBs. [ABSTRACT FROM AUTHOR]

A series of Al-doped Li 1+x Ni 0.5 Al x Mn 1.5-x O 4 cathode materials for lithium ion batteries are successfully synthesized via a co-precipitation method. Raman spectroscopy studies reveal that the cation-disordered tends to increase with the content of Al. The data of X-ray photoelectron spectroscopy (XPS) depth profiles reveal that the inert Al 3+ ions segregates preferentially to the surface during the synthesis process. The results of the electrochemical tests suggest that the substitution of a small amount of Al has the ability to improve the rate capability of LiNi 0.5 Mn 1.5 O 4 spinel with conventional electrolytes. Especially, the Al-doped (x = 0.06) sample delivers a long cycle-life at high rate (20 C). The enhanced performance is attributed to the formation of Al-enriched surface, providing a more stable interface with the electrolyte at high voltage (∼4.7 V), along with the stabilization of the spinel structure with a disordering of the cations and improved Li-ion diffusion, based on results of the potentiostatic intermittent titration technique. [ABSTRACT FROM AUTHOR]

A new electrolyte based on fluorinated 3-(1,1,2,2-tetrafluoroethoxy)-1,1,2,2-tetrafluoropropane (F-EPE) solvent is studied in LiNi 0.5 Mn 1.5 O 4 /Li cells. The electrochemical stability of the electrolyte with 10% F-EPE is carried out by linear sweep voltammetry and electrochemical floating test. These results indicate that the electrolyte with F-EPE has an oxidation potential of more than 5.2 V vs. Li + /Li, which is higher than that without F-EPE and enlarges the oxidative window of electrolyte. A thin and uniform SEI layer is formed on the surface of LiNi 0.5 Mn 1.5 O 4 cathode by using electrolyte with F-EPE, leads to an improvement in the electrochemical performance, validated by charge-discharge tests, EIS, SEM, TEM, and XPS analysis. [ABSTRACT FROM AUTHOR]

Ni-rich layered oxide materials have become a major choice of cathode material for electrical vehicle batteries. However, it is an outstanding challenge to improve the safety performance of these batteries as the energy density of the batteries increases with higher Ni content in the cathode material. Here we demonstrate that Ni-rich LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM622) based 10 Ah pouch cells can pass nail-penetration and overcharging tests by introducing nanometer-sized LiMn 0.7 Fe 0.3 PO 4 (LMFP) particles in the cathode slurry. Since LMFP exhibits appreciable Li storage capacity in the battery operation voltage window, it brings no compromise in electrochemical performance to the cell. It is shown that LMFP improves the safety feature of the cell by partially blocking the NCM622/electrolyte interface, thereby alleviates parasitic reaction between NCM622 and electrolyte, which delays the phase transformation of NCM622 during thermal runaway as well as reduces heat generation between charged cathode and liquid electrolyte. • A facile method that improves the safety performance of NCM622 pouch cells is reported. • There is no compromise in electrochemical performances for improved NCM622 cells. • 5 wt% LiMn 0.7 Fe 0.3 PO 4 additive enables NCM622 pouch cells pass nail penetration. • LiMn 0.7 Fe 0.3 PO 4 delays the phase transformation of NCM622 during thermal runaway. [ABSTRACT FROM AUTHOR]