Abstract
Lithium-rich manganese oxide is a promising candidate for the next-generation cathode material of lithium-ion batteries because of its low cost and high specific capacity. Herein, a series of xLi2MnO3·(1 − x)LiMnO2 nanocomposites were designed via an ingenious one-step dynamic hydrothermal route. A high concentration of alkaline solution, intense hydrothermal conditions, and stirring were used to obtain nanoparticles with a large surface area and uniform dispersity. The experimental results demonstrate that 0.072Li2MnO3·0.928LiMnO2 nanoparticles exhibit a desirable electrochemical performance and deliver a high capacity of 196.4 mAh g−1 at 0.1 C. This capacity was maintained at 190.5 mAh g−1 with a retention rate of 97.0% by the 50th cycle, which demonstrates the excellent cycling stability. Furthermore, XRD characterization of the cycled electrode indicates that the Li2MnO3 phase of the composite is inert, even under a high potential (4.8 V), which is in contrast with most previous reports of lithium-rich materials. The inertness of Li2MnO3 is attributed to its high crystallinity and few structural defects, which make it difficult to activate. Hence, the final products demonstrate a favorable electrochemical performance with appropriate proportions of two phases in the composite, as high contents of inert Li2MnO3 lower the capacity, while a sufficient structural stability cannot be achieved with low contents. The findings indicate that controlling the composition through a dynamic hydrothermal route is an effective strategy for developing a Mn-based cathode material for lithium-ion batteries.
Highlights
Since rechargeable lithium-ion batteries were first applied to electronic products in the 1990s, their development has been continual [1]
The high crystallinity and phase composition of the hydrothermally synthesized xLi2MnO3·(1 − x)LiMnO2 samples were distinctly confirmed by X-ray diffraction (XRD) measurement (Figure 1a)
The intensity of the peaks at 18.7◦ and 44.7◦ can be ascribed to Li2MnO3 with the C/2m space group, declining gradually as the oxygen in the autoclave decreased, which was more obvious in the enlarged interval between 42◦ and 48◦ (Figure 1b). This trend can be attributed to residual oxygen in the reaction system inevitably producing Li2MnO3, and the chemical reaction can be formulated as follows: Mn(II) + MnO2 + 4Li+ + 6OH− + 1/2O2 → 2Li2MnO3 + 3H2O
Summary
Since rechargeable lithium-ion batteries were first applied to electronic products in the 1990s, their development has been continual [1]. The most widely used cathode materials are ternary NMC and LiFePO4, while Li-rich manganese-based materials have attracted considerable attention due to their low cost and high specific capacity. This type of cathode material, noted as xLi2MnO3·(1 − x)LiTMO2 (transition metal (TM) = Ni, Co, and Mn, etc.), exhibits a superior specific capacity (>250 mAh g−1) and high operation voltage to realize an excellent energy density; xLi2MnO3·(1 − x)LiTMO2 is assumed to be a promising cathode material for the generation of lithium-ion batteries [8]. The specific capacity of xLi2MnO3·(1 − x)LiMnO2 has been significantly improved in comparison with common lithium manganese oxides (LiMn2O4, LiMnO2), but its capacity degradation during cycling is relatively severe [15]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
