The search for advanced electrode materials in K-ion batteries (KIBs) is a significant challenge due to the lack of an efficient throughput screening method in modern battery technology. Layered oxides...

In this study, magnesium-ion-substituted, sodium-deficient, P3-and P2layered manganese oxide cathodes (Na 0.67 Mg 0.1 Mn 0.9 O 2 ) were synthesized through a facile polyol-assisted combustion technique for applications in sodium-ion batteries. The electrochemical reaction pathways, structural integrity, and long cycling ability at low current rates of the P3-and P2-phases of the Na 0.67 Mg 0.1 Mn 0.9 O 2 cathodes were investigated using time-consuming techniques, such as galvanostatic titration and series cyclic voltammetry. The results obtained from these techniques were supported by those obtained from operando X-ray diffraction (XRD) analysis. Particularly, the P2phase provided excellent structural stability owing to its intrinsic crystal structure, thereby exhibiting a reversible capacity retention of 82.6% after 262 cycles at a low rate of 0.1 C; in contrast, the P3-phase exhibited a capacity retention of 38.7% after 241 cycles at a similar current rate. The air stability of these as-prepared powders, which were stored under ambient conditions, was progressively analyzed over a period of 6 months through XRD without conducting any special experiments. The results suggest that in the P3-phase, the formation of NaHCO 3 and hydrated phase impurities, resulting from Na + /H + exchange and hydration reactions, respectively, was likely to occur more quickly, that is, within a few days, compared to that in the P2-phase.

In this study, nickel tellurium oxide (Ni 3 TeO 6 ) was composited with carbon nanotubes (CNTs) through the high-energy ball-milling method and proposed as a high-energy conversion-type anode for sodium-ion batteries (SIBs) for the first time. Upon mechanical milling, the Ni 3 TeO 6 nanoparticles were uniformly encapsulated and wedged within the CNTs matrix, which produced a nano/micro hybrid structure. The interconnected CNT network in the composite provided conductive paths for rapid electron transport while effectively suppressing the local stress caused by large volume changes of Ni 3 TeO 6 during the sodiation-desodiation process. The Ni 3 TeO 6 @CNTs exhibited a high Na +ion storage capacity of 495 mA h g À1 , good cycling stability at 200 mA g À1 , and high-rate performance up to 2000 mA g À1 .

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Research attention in aqueous rechargeable zinc-ion batteries (ARZIBs) is growing immensely because of their low-cost and eco-friendly cell components. However, its challenging to find new cathode materials towards practical application of ARZIBs. In this contribution, ground-breaking work on the potassium-pillared V2O5.nH2O (K0.5V2O5.nH2O) nanorod with exposed layer structure as high-performance cathode for ARZIB is presented. The storage mechanism of the K0.5V2O5.nH2O cathode in ARZIB is systematically elucidated using a combined of in situ synchrotron X-ray diffraction, ex situ synchrotron X-ray absorption spectroscopy, ex situ TEM analyses, and first-principle calculations. The K0.5V2O5. nH2O cathode displays a notable discharge capacity of 439 mAh g−1 at a current density of 50 mA g−1. Furthermore, it recovers 96% of the capacity after 1500 cycles at 8000 mA g−1. Impressively, the Zn/K0.5V2O5.nH2O battery offers a specific energy of 121 Wh kg−1 at a high specific power of 6480 W kg−1. The superior performance of the cathode is attributed to its unique exposed layer structure with high surface energy, high conductivity, and low migration barrier. The zinc (Zn) insertion pathway into K0.5V2O5.nH2O was studied using density function theory (DFT). This study provides an insight for designing high-performance cathode materials for ARZIBs and other electrochemical systems.