Hydrothermal synthesis of orthorhombic LiMnO2 nano-particles and LiMnO2 nanorods and comparison of their electrochemical performances

Abstract

Orthorhombic LiMnO 2 nanoparticles and LiMnO 2 nanorods have been synthesized by hydrothermal methods. LiMnO 2 nanoparticles were synthesized by simple one-step hydrothermal method. To obtain rod-like LiMnO 2 , -MnOOH nanorods were fi rst synthesized and then the H + ions were completely replaced by Li + resulting in LiMnO 2 nanorods. Their electrochemical performances were thoroughly investigated by galvanostatic tests. Although the LiMnO 2 nanoparticles have smaller size than LiMnO 2 nanorods, the latter exhibited higher discharge capacity and better cyclability. For example, the discharge capacities of LiMnO 2 nanorods reached 200 mA·h/g over many cycles and remained above 180 mA·h/g after 30 cycles. However, the maximum capacity of LiMnO 2 nanoparticles was only 170 mA·h/g and quickly decreased to 110 mA·h/g after 30 cycles. Nanorods with one-dimensional electronic pathways favor the transport of electrons along the length direction and accommodate volume changes resulting from charge/discharge processes. Thus the morphology of LiMnO 2 may play an important role in electrochemical performance.

Facile synthesis of LiCoO2 nanowires with high electrochemical performance

“…Zhou et al reported that LiMn 2 O 4 nanowires have high-rate performance with its the discharge capacity reaching 118, 108, 102, and 88 mA·h/g at rates of 0.1, 5, 10, and 20 A/g, respectively [16]. Our work has also shown that LiMnO 2 nanorods exhibited higher discharge capacity and better cyclability than LiMnO 2 nanoparticles [17]. In addition to these examples of cathode materials, similar phenomena have also been found for many anode materials, such as SnO 2 [18], Si [19], Co 3 O 4 [20], TiO 2 [21], CoSb [22].…”

Evaluating the performance of nanostructured materials as lithium-ion battery electrodes

“…The increased capacity was attributed to the unique 1D morphology, through which better strain accommodation and facile Li + transport may have resulted. Early increases in capacity during electrochemical cycling however, suggests some spinel formation may have occurred although this remained unquantified in the study [288]. Capacity fade as a result of cubic spinel formation may, however, ultimately render LiMnO2 electrodes unviable candidates unless such transitions are facilitated.…”

“…While the transition seemingly affects the initial cycling behaviour of LiMnO2, an insignificant contribution is suggested for the 5 th and subsequent cycles [287]. Recently published reports of various nanostructured Li/MnO2 architectures include nanorods/nanoparticles [288], mesoporous [289] and nanocrystalline solids [286,290,291]. For example, the hydrothermal treatment of γ-MnOOH nanorod templates with LiOH at 200 °C resulted in orthorhombic LiMnO2 nanorods which delivered a capacity of 180 mA h g -1 after 30 cycles [288].…”

LiMn2O4 microspheres: Synthesis, characterization and use as a cathode in lithium ion batteries

“…For example, Wan's group has calculated that a reduction of diffusion length from 10 μm (the typical particle size of commercial electrode materials) to 100 nm, results in a decrease in the mean diffusion time from 5000 to 0.5 s [14]. Many reports have also demonstrated that smaller particles of electrode materials have shorter diffusion lengths for Li + , higher electrode/electrolyte contact areas, and better accommodation of the strain than common micron-sized materials [15][16][17][18][19].…”