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Enhancement of the discharge capacity, high-rate capability, and cycle stability of the Li-rich layered Li(Li 0.17 Ni 0.25 Mn 0.58 )O 2 oxide with a large specific capacity is highly significant for high energy lithiumion batteries. In this work, the Li-rich layered Li(Li 0.17 Ni 0.25 Mn 0.58 )O 2 oxide is prepared by a spray-drying method. The surface modification with the Li-Mn-PO 4 is introduced onto Li-rich layered Li(Li 0.17 Ni 0.25 Mn 0.58 )O 2 oxide for the first time. It is demonstrated that the surface of Li(Li 0.17 Ni 0.25 Mn 0.58 ) O 2 grains is coated with the thin amorphous Li-Mn-PO 4 layer (5 wt%). With increasing calcination temperature after the surface coating, a strong interaction can be induced on the interface between the amorphous Li-Mn-PO 4 layer and the top surface of Li(Li 0.17 Ni 0.25 Mn 0.58 )O 2 grains. As anticipated, the discharge capacity and high-rate capability are obviously improved for the Li-Mn-PO 4 -coated sample after calcination at 400 C, while excellent cycle stability is obtained for the Li-Mn-PO 4 -coated sample after calcination at 500 C as compared with the as-prepared Li(Li 0.17 Ni 0.25 Mn 0.58 )O 2 oxide during cycling. Apparently, the interface interaction between the amorphous Li-Mn-PO 4 layer and the top surface of Li(Li 0.17 Ni 0.25 Mn 0.58 )O 2 grains is responsible for the improvement of the reaction kinetics and the electrochemical cycle stability of Li-Mn-PO 4 -coated samples.

Sulfur–carbon composites were prepared by an in situ sulfur deposition route developed for the heterogeneous nucleation of sulfur into nanopores of conductive carbon black (CCB) by fumigation of Na2S4/CCB powder with HCl. The sulfur–carbon composites demonstrate enhanced reversible capacity and stable cycle performance.

Rechargeable aqueous TiO2/LiMn2O4 lithium-ion battery is fabricated by combining the TiO2 nanotube arrays on metallic titanium foil as anode and LiMn2O4 as cathode in aqueous solution with mixed lithium salts (LiCl and Li2SO4). It is shown from cyclic voltammograms that the lithium insertion/extraction peaks of the cathode are highly symmetrical before the oxygen evolution, which can ensure a good lithium utilization of the LiMn2O4. Importantly, a higher anodic hydrogen evolution overpotential in TiO2 anode is observed, which is essential for the facile lithium insertion in preference to the hydrogen evolution. Meanwhile, the gas (hydrogen and oxygen) evolution in the anodic and cathodic processes can be effectively suppressed in aqueous electrolyte with mixed lithium salts as compared with that in pure LiCl and Li2SO4 solution, respectively. Correspondingly, the fabricated TiO2/LiMn2O4 battery presents a high discharge voltage plateau of above 2 V, which is well beyond the average discharge voltage of current aqueous battery system. Therefore, the combination of the appropriate anode/cathode-active materials with a relatively large potential difference and high gas evolution overpotential is an ideal strategy for developing new aqueous battery system based on reversible lithium insertion/extraction reactions in aqueous electrolyte.

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Highly soluble active materials, such as iodine, are of great potential to develop the research of rapid charge-discharge performance for Li-ion batteries. In this work, a new facile method is applied to construct the iodine/carbon electrode system, which is composed of a thin cathode film, prepared by directly mixing pure commercial iodine and superconducting carbon black, and a carbon nanotubes (CNTs) interlayer. The CNTs interlayer is inserted between pure iodine cathode and separator in the lithium-iodine battery. Electrochemical data reveals that the iodine cathode demonstrates a high capacity of 100 mAh g −1 and ∼100% columbic efficiency after 5000 cycles at a rate of 100C, which shows a great cycle stability and superior high-rate capability, based on the contributions from both the confinement effect of iodine species in CNTs interlayer and the quick liquid-phase diffusion of Li ions in Li-I 2 battery.

Recently, ferrate(VI) has been widely investigated as a cathode material in alkaline batteries. The cathodic reduction process of the ferrate electrode is very important in understanding the electrochemical mechanism as well as in utilizing ferrate as a battery material. In this work, the direct electrochemical reduction process of normalK2FeO4 was investigated by linear sweep voltammetry (LSV), with a porous Pt black electrode in a 9 M KOH solution at 25°C . The cathodic reaction process of FeO42− is controlled by the diffusion process in a potential range from 0.20 to 0.53 V (vs Hg/HgO). Moreover, the totally irreversible cathodic reactions of FeO42− include a rate-controlling step with an electron-transfer number less than 3. Sampled-current voltammetry was also applied to investigate the reaction processes, and the plot exhibits two limited currents. The first one is a weak one-electron limited current, corresponding to the rate-controlling step analyzed by LSV; the other one is a two-electron current. They are both affected by the diffusion of FeO42− ions. Therefore, the electrochemical reduction mechanism of FeO42− in 9 M KOH can be inferred as an overall three-electron process with a one-electron transfer as the rate-controlling step, in which the intermediate state of Fe(V) is generated from ferrate(VI).