Abstract
Li-rich layered oxide cathode materials have become one of the most promising cathode materials for high specific energy lithium-ion batteries owning to its high theoretical specific capacity, low cost, high operating voltage and environmental friendliness. Yet they suffer from severe capacity and voltage attenuation during prolong cycling, which blocks their commercial application. To clarify these causes, we synthesize Li1.5Mn0.55Ni0.4Co0.05O2.5 (Li1.2Mn0.44Ni0.32Co0.04O2) with high-nickel-content cathode material by a solid-sate complexation method, and it manifests a lot slower capacity and voltage attenuation during prolong cycling compared to Li1.5Mn0.66Ni0.17Co0.17O2.5 (Li1.2Mn0.54Ni0.13Co0.13O2) and Li1.5Mn0.65Ni0.25Co0.1O2.5 (Li1.2Mn0.52Ni0.2Co0.08O2) cathode materials. The capacity retention at 1 C after 100 cycles reaches to 87.5% and the voltage attenuation after 100 cycles is only 0.460 V. Combining X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscopy (TEM), it indicates that increasing the nickel content not only stabilizes the structure but also alleviates the attenuation of capacity and voltage. Therefore, it provides a new idea for designing of Li-rich layered oxide cathode materials that suppress voltage and capacity attenuation.
Highlights
Advanced lithium-ion batteries (LIBs) technology have promoted the rapid development of mobile electronic devices owning to their low cost, long life, lack of any memory effect and environmental friendliness [1,2,3]
The cause of voltage attenuation is generally attributed to a continuous phase transition from layered phase to spinel during the repeated extraction/insertion processes [19,21,30], corresponding to the irreversible migration of the transition metal (TM) ions, during the course of which they move from the octahedral sites in the TM slab to the octahedral sites in the Li slab during the lithium ion extraction/insertion processes [31]
The synthesized sample, acetylene black (AR, Hersbit Chemical Co., Ltd., Shanghai, China) and polyvinylidene difluoride (PVDF, FR905, San ai fu New Material Technology Co., Ltd., Shanghai, China) with a weight ratio of 8:1:1 to make a slurry in the N-methyl pyrrolidone (NMP) solvent
Summary
Advanced lithium-ion batteries (LIBs) technology have promoted the rapid development of mobile electronic devices owning to their low cost, long life, lack of any memory effect and environmental friendliness [1,2,3]. The cause of voltage attenuation is generally attributed to a continuous phase transition from layered phase to spinel during the repeated extraction/insertion processes [19,21,30], corresponding to the irreversible migration of the transition metal (TM) ions, during the course of which they move from the octahedral sites in the TM slab to the octahedral sites in the Li slab during the lithium ion extraction/insertion processes [31] It is possible for Li-rich layered oxide cathode materials to prevent collapse of the layered structure by minimizing the tension between the neighboring oxygen layers in its deep delithiation state. Jahn-Teller effect caused by Mn3+ ions and effectively improves structural durability [41,42,43]
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