A modified Ni-rich Li[NiCoMn]O cathode material with exposed {010} planes is successfully synthesized for lithium-ion batteries. The scanning electron microscopy images have demonstrated that by tuning the ammonia concentration during the synthesis of precursors, the primary nanosheets could be successfully stacked along the [001] crystal axis predominantly, self-assembling like multilayers. According to the high-resolution transmission electron microscopy results, such a morphology benefits the growth of the {010} active planes of final layered cathodes during calcination treatment, resulting in the increased area of the exposed {010} active planes, a well-ordered layer structure, and a lower cation mixing disorder. The Li-ion diffusion coefficient has also been improved after the modification based on the results of potentiostatic intermittent titration technique. As a consequence, the modified Li[NiCoMn]O material exhibits superior initial discharges of 201.6 mA h g at 0.2 C and 185.7 mA h g at 1 C within 2.8-4.3 V (vs Li/Li), and their capacity retentions after 100 cycles reach 90 and 90.6%, respectively. The capacity at 10 C also increases from 98.3 to 146.5 mA h g after the modification. Our work proposes a novel approach for exposing high-energy {010} active planes of the layered cathode material and again confirms its validity in improving electrochemical properties.
Enhancement of lignin reactivity plays a critical role in the chemical modification of lignin. In the current study, a simple, green, and effective method, of ozone oxidation, was developed to improve the reactivity of enzymatic lignin through the formation of carboxyl groups. The resultant ozonate of enzymatic lignin (OzEL) indicated a higher reactivity of esterification. The ozonated enzymatic lignin grafted to polyethylene glycol (OzEL-PEGs) afforded satisfactory water solubility, good surface activity, and good emulsifying properties. The remaining phenolic hydroxyl groups in OzEL-PEGs also maintain excellent antioxidant and UV absorbing properties. This ozone oxidation process provides an effective and green method for the preparation of highly reactive lignin, which can be applied in the manufacture of a multifunctional lignin polymer.
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