Monodisperse Li1.2Mn0.6Ni0.2O2 microspheres with enhanced lithium storage capability

Abstract

Monodisperse spherical Mn 0.75 Ni 0.25 (OH) 2 precursors built up from plate-like primary particles have been successfully synthesized by the control of pH values during a co-precipitation reaction. The size of spherical particles, namely the secondary particles, is observed to decrease with increasing pH value from 9.0 to 11.0, and is accompanied by a series of shape changes of the primary particles from closepacked plates to well-exposed nanoplates, and then to nanoparticles. Further lithiation of these hydroxide precursors produces the final lithium-rich layered Li 1.2 Mn 0.6 Ni 0.2 O 2 cathode materials without destroying the morphology of the precursors. Electrochemical measurements show that the spherical cathode material assembled from well-exposed nanoplates exhibits superior rate capability and good cyclability compared to other electrode materials, which can be attributed to its uniform particle size and the favorable shape which facilitates the diffusion of lithium ions. Through the control of the sample morphologies, we provide a simple and effective way to enhance the lithium storage capability of lithium-rich layered oxide cathode materials for high-performance lithium-ion batteries.

Ultrasonic-assisted co-precipitation to synthesize lithium-rich cathode Li1.3Ni0.21Mn0.64O2+ materials for lithium-ion batteries

“…Both electrodes exhibit a sloping region followed by a long 4.5 V plateau during the first charge process. The initial capacity at less than 4.4 V is due to the oxidation of Ni 2+ to Ni 4+ , and the capacity observed in the plateau region between 4.4 and 4.8 V comes from the activation of Li 2 MnO 3 , which is in agreement with previous reports [22][23][24] . The cycling performance of both electrodes at 0.1 C is shown in Fig.…”

Solution combustion synthesis and enhanced electrochemical performance Li1.2Ni0.2Mn0.6O2 nanoparticles by controlling NO3–/CH3COO– ratio of the precursors

“…The discharge capacity of LLO-3N1A is obviously higher than that of the other three samples. The value is higher than that of Cheng et al [34]. Similar trends are also shown at 0.2 C, 0.5 C, 1 C, 2 C and 3 C. Clearly, LLO-3N1A shows the best rate performance.…”

“…For instance, surface nitridation [16] or coating with oxides [11,[18][19][20][21][22], fluorides [23,24], phosphates [25,26] and carbon [27,28] are proved to be effective to improve the electrochemical performance of lithium-rich layered oxides. In addition, fabrication of cathode material with reduced particle size is also demonstrated to improve the high-rate capability of lithium-rich layered oxides [29][30][31][32][33][34][35]. However, the above lithiumrich layered oxides with a primary particle size of 100-300 nm are relatively large.…”

Effective enhancement of the electrochemical performance of layered cathode Li1.5Mn0.75Ni0.25O2.5via a novel facile molten salt method

“…Currently, the family of lithium-rich layered oxides Li 1+y M 1-y O 2 (also write as xLi 2 MnO 3 ·(1-x)LiMO 2 , M = Ni, Co, Mn) have attracted much attention, due to their encouraging high reversible capacity over 250 mAh g -1 when initially charged above 4.5 V. [8][9][10] Among these lithium-rich oxides, the Li-rich Mn-based nickel oxide Li 1.5 Mn 0.75 Ni 0.25 O 2.5 is the most appealing one due to its high discharge capacity, low cost, good safety and less toxicity. [11][12][13] However, it suffers several serious drawbacks needed to be resolved, such as its intrinsically inferior rate capability, poor cycle performance, a large irreversible capacity loss (ICL) in the initial cycle, and voltage decay during long-term cycling resulting from phase transformation from layered to spinel/layered intergrowth structure. [14][15][16] To address these obstacles, many strategies have been developed, especially regarding the synthesis methods.…”