A composite electrolyte based on a garnet electrolyte (LLZO) and polyester-based co-polymer (80:20 ε-caprolactone (CL)-trimethylene carbonate, PCL-PTMC with LiTFSI salt) is prepared. Integrating the merits of both ceramic and co-polymer electrolytes is expected to address the poor ionic conductivity and high interfacial resistance in solid-state lithium-ion batteries. The composite electrolyte with 80 wt % LLZO and 20 wt % polymer (PCL-PTMC and lithium bis­(trifluoromethanesulfonyl)­imide (LiTFSI) at 72:28 wt %) exhibited a Li-ion conductivity of 1.31 × 10–4 S/cm and a transference number (t Li+ ) of 0.84 at 60 °C, notably higher than those of the pristine PCL-PTMC electrolyte. The prepared composite electrolyte also exhibited an electrochemical stability of up to 5.4 V vs Li+/Li. The interface between the composite electrolyte and a LiFePO4 (LFP) cathode was also improved by direct incorporation of the polymer electrolyte as a binder in the cathode coating. A Li/composite electrolyte/LFP solid-state cell provided a discharge capacity of ca. 140 mAh/g and suitable cycling stability at 55 °C after 40 cycles. This study clearly suggests that this type of amorphous polyester-based polymers can be applied in polymer-in-ceramic composite electrolytes for the realization of advanced all-solid-state lithium-ion batteries.

The well-established poor electrochemical cycling performance of the LiMn2O4 (LMO) spinel cathode material for lithium-ion batteries at elevated temperature stems from the instability of the Mn(3+) concentration. In this work, a microwave-assisted solid-state reaction has been used to dope LMO with a very low amount of nickel (i.e., LiNi0.2Mn1.8O4, herein abbreviated as LMNO) for lithium-ion batteries from Mn3O4 which is prepared from electrolytic manganese oxide (EMD, γ-MnO2). To establish the impact of microwave irradiation on the electrochemical cycling performance at an elevated temperature (60 °C), the Mn(3+) concentration in the pristine and microwave-treated LMNO samples was independently confirmed by XRD, XPS, (6)LiMAS-NMR and electrochemical studies including electrochemical impedance spectroscopy (EIS). The microwave-treated sample (LMNOmic) allowed for the clear exposure of the {111} facets of the spinel, optimized the Mn(3+) content, promoting structural and cycle stability at elevated temperature. At room temperature, both the pristine (LMNO) and microwave-treated (LMNOmic) samples gave comparable cycling performance (>96% capacity retention and ca. 100% coulombic efficiency after 100 consecutive cycling). However, at an elevated temperature (60 °C), the LMNOmic gave an improved cycling stability (>80% capacity retention and ca. 90% coulombic efficiency after 100 consecutive cycling) compared to the LMNO. For the first time, the impact of microwave irradiation on tuning the average manganese redox state of the spinel material to enhance the cycling performance of the LiNi0.2Mn1.8O4 at elevated temperature and lithium-ion diffusion kinetics has been clearly demonstrated.

No abstract

A new class of 2D nanosheets of nitrogen-integrated phosphate-rich ammonium manganese phosphate hydrate, (NH 4 MnPO 4 • H 2 O) (AMP), has been developed as pseudocapacitive electrode materials. The optimized electrodes exhibited device capacitances of 48.4 and 65.4 F/g for symmetric and asymmetric configurations, respectively. The devices showed excellent energy and power (e.g., 29.4 Wh/kg and 133 kW/kg for asymmetric cells) with extraordinary capacitance retention (e.g., >93%, 100 000 cycles at 5 A/g for asymmetric cells) that surpass those of most of the reported values. The huge pseudocapacitance of AMP is attributed to several factors, including the electroactive sites containing NH 4 + ions, the conductive inorganic layers, intercalated water interactions of Mn 2+ •••H 2 O, redox-active phosphate ions, and the 2D nanosheets. AMP-based all-solid-state flexible asymmetric devices exhibited >95% capacitance retention upon 1000 repetitive charge−discharge cycles. This study opens doors to elegant strategies of unlocking the rich physicoelectrochemical properties of 2D AMP for next-generation pseudocapacitors.

Microwave irradiation at the pre-and post-annealing steps of the synthesis of LiAl x Mn 2Àx O 4 (x ¼ 0 and 0.3) spinel cathode materials for rechargeable lithium ion batteries is a useful strategy to optimize the average manganese valence number (n Mn ) for enhanced capacity and capacity retention. The strategy impacts on the lattice parameter, average manganese valence, particle size and morphology, reversibility of the deintercalation/intercalation processes, and capacity retention upon continuous cycling. Microwave irradiation is able to shrink the particles for improved crystallinity. The XPS data clearly suggest that microwave irradiation can be used to tune the manganese valence (n Mn ), and that the LiAl x Mn 2Àx O 4 with n Mn z 3.5+ gives the best electrochemical performance. These new findings promise to revolutionize how we use microwave irradiation in the preparation of energy materials and various other materials for energy storage and conversion materials for enhanced performance.

No abstract

No abstract

P2-type Na 0.67 Mg 0.28 Mn 0.72 O 2 based cathode materials for sodium-ion batteries were prepared using combustion synthesis. The effect of microwave irradiation and fluorination was investigated with the aim to improve the electrochemical performance. Four samples were considered: samples were prepared by the combustion method (NaMgMnO-a) and then either microwave-irradiated or fluorinated (NaMgMnO-ma and NaMgMnO-af, respectively) or both microwave-irradiated and fluorinated (NaMgMnO-maf). The powder XRD analyses showed that pure single phase P2-type powders were successfully prepared. SEM analyses revealed an impact of microwave irradiation and fluorination on the morphology of the materials, suggesting a change in the electrochemical performance. The galvanostatic charge-discharge studies revealed that both microwave irradiation and fluorination improved the capacity and cycle performance. The electrochemical data (from first discharge capacity to coulombic efficiency, capacity retention, cyclability and impedance) show that microwave-and fluorine-treated samples performed better. The key finding clearly shows the impact of microwave irradiation and fluorination processes in suppressing the P2-O2 phase transformation process and the The extensive use of lithium-ion batteries (LIBs) in portable electronic devices such as cellphones, laptops, and electric vehicles will eventually increase the cost and the demand of LIBs.1 Sodium-ion batteries (SIBs) have currently drawn wide attention as the most attractive alternative for LIBs for smart grid applications.2-4 This is because sodium is cheap and abundant as it is the 4 th most abundant element in the earth's crust and is uniformly distributed around the world.5 SIBs also have high voltage, high energy density and long cycle life. 6-8The cathode materials for SIBs include layered oxides, olivines, NASICONs, etc. Among them, layered P2-type manganese oxide (MnO 2 )-based materials have been widely studied and continued to attract major research interests as promising cathode materials for SIBs.9-17 This is due to the abundance of manganese, importantly P2-type MnO 2 -based materials offer larger tunnels for the intercalation and de-intercalation of the sodium-ion and have been reported to have high capacities.18-20 A sodium-ion layered oxide material crystallizes into either P2-type or O3-type structural phases or mixture of both. In the P2-type phase, the sodium-ion is coordinated in the prismatic sites between the TMO 2 (TM = transition metal) sheets and there are two repeating TMO 2 layers in the unit cell (Fig. 1). 2,21,22 In O3-type the sodium-ion is coordinated in the octahedral site and there are three repeating MO 2 layers in the unit cell. P2-type phase is advantageous compared to O3-type phases as it allows easy intercalation and deintercalation of Na ions and increases the number of the ions that can be intercalated and de-intercalated. 2,23Sodium magnesium manganese oxide, Na 0.67 Mg 0.28 Mn 0.72 O 2 , abbreviated herein simply as NaMgMnO, is well kno...