LiNi0.6Co0.2Mn0.2O2 cathode material has been surface-modified by coating with ultrathin TiO2via atomic layer deposition (ALD) technology to improve the electrochemical performance of LiNi0.6Co0.2Mn0.2O2 cathodes for lithium ion batteries. Within the cut-off voltage of 2.5-4.3 V, the coated sample delivers an initial discharge capacity of 187.7 mA h g(-1) at 0.1 C and with a capacity retention about 85.9% after 100 cycles at 1 C, which provides a significant improvement in terms of discharge capacity and cyclability, as compared with those of the bare one. Such enhanced electrochemical performance of the coated sample is ascribed to its high-quality ultrathin coating of amorphous TiO2, which can protect the active material from HF attack, withstand the dissolution of metal ions in the electrode and favor the lithium diffusion of oxide as proved by electrochemical impedance spectroscopy (EIS) tests. TiO2 coating via the ALD process provides a potential approach for battery factories to surface-modify Ni-rich electrode materials so as to realize improvements in electrochemical performance.

Preparing high-performance LiMnPO 4 is still a large obstacle due to its sluggish electrochemical kinetics. To overcome this problem, a novel method is developed for LiMnPO 4 /C nanoplates from nanoporous Mn 2 O 3 precursors. There are two advantages. Firstly, through negative pressure immersion, lithium dihydrogen phosphate (LiH 2 PO 4 ), lithium hydroxide (LiOH) and sucrose (C 12 H 22 O 11 ) are deposited on the surface of porous Mn 2 O 3 nanosheets. Following solid-state reaction, three dimensional continous conductive carbon wrapped LiMnPO 4 /C nanoplates up uniformly, which improved the conductivity greatly. Secondly, (010) exposed facets are obtained using Mn 2 O 3 hierarchical microspheres as precursors, which allows for a fast transmission of Li + ion to improve the rate capability. As a results, as-synthesized L-Mn 2 O 3 -LMP/C samples exhibit a superior rate performance with discharge capacities of 157.3 mA h g -1 at C/20, 122.6 mA h g -1 at 1 C, and 105.8 mA h g -1 at 2 C. Meanwhile, they can retain 99.3% of the initial capacity after 100 cycles at 1C, revealing an excellent cycling stability. This method shields more light on the fabrication of high-performance LiMnPO 4 /C cathode materials and is suitable for large scale production.

No abstract