In this study, a facile nanoetching-template route is developed to synthesize porous nanomicrohierarchical LiNi1/3Co1/3Mn1/3O2 microspheres with diameters below 1.5 μm, using porous CoMnO3 binary oxide microspheres as the template. The unique morphology of CoMnO3 template originates from the contraction effect during the oxidative decomposition of Ca0.2Mn0.4Co0.4CO3 precursors and is further improved by selectively removing calcium carbonate with a nanoetching process after calcination. The as-synthesized LiNi1/3Co1/3Mn1/3O2 microsphere, composed of numerous primary particles and pores with size of dozens of nanometers, illustrates a well-assembled porous nanomicrohierarchical structure. When used as the cathode material for lithium-ion batteries, the as-synthesized microspheres exhibit remarkably enhanced electrochemical performances with higher capacity, excellent cycling stability, and better rate capability, compared with the bulk counterpart. Specifically, hierarchical LiNi1/3Co1/3Mn1/3O2 achieves a high discharge capacity of 159.6 mA h g(-1) at 0.2 C with 98.7% capacity retention after 75 cycles and 133.2 mA h g(-1) at 1 C with 90% capacity retention after 100 cycles. A high discharge capacity of 135.5 mA h g(-1) even at a high current of 750 mA g(-1) (5 C) is also achieved. The nanoetching-template method can provide a general approach to improve cycling stability and rate capability of high capacity cathode materials for lithium-ion batteries.

In this study, a hard-templating route was developed to synthesize a 3D reticular LiNiMnO cathode material using ordered mesoporous silica as the hard template. The synthesized 3D reticular LiNiMnO microparticles consisted of two interlaced 3D nanonetworks and a mesopore channel system. When used as the cathode material in a lithium-ion battery, the as-synthesized 3D reticular LiNiMnO exhibited remarkably enhanced electrochemical performance, namely, superior rate capability and better cycling stability than those of its bulk counterpart. Specifically, a high discharge capacity of 195.6 mA h g at 1 C with 95.6% capacity retention after 50 cycles was achieved with the 3D reticular LiNiMnO. A high discharge capacity of 135.7 mA h g even at a high current of 1000 mA g was also obtained. This excellent electrochemical performance of the 3D reticular LiNiMnO is attributed to its designed structure, which provided nanoscale lithium pathways, large specific surface area, good thermal and mechanical stability, and easy access to the material center.

Ni-rich LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM) material has attracted intense attention because of the capacity and cost advantages. However, the poor cycling performance hampers the further development of NCM. As a coating layer, polysiloxane can improve the electrochemical properties of the NCM by eliminating remaining H 2 O on the surface of NCM and the reaction between HF in electrolyte and NCM, inhibiting the interfacial side reactions. Compared with the pristine NCM, the cycling performance of the NCM cathode coated with polysiloxane is significantly improved. The capacity retention of NCM coated with polysiloxane is 91.5% at 1 C after 120 cycles, while pristine NCM only maintains 71.4%. This study provides a method to alleviate the effects of interfacial side reactions and HF corrosion on NCM performance degradation after many cycles.

No abstract

Anodes composed of Mn3O4 deliver a much higher specific capacity in Li-ion batteries (LIBs) than that of commercial graphite but suffer from poor cycling stability, a poor rate characteristic, and a high overpotential stemming from volumetric changes during cycling, low electroconductibility, and insufficient ion diffusivity. To make Mn3O4 more applicable, we developed a convenient one-pot synthesis route to fabricate porous hierarchical spherical Mn3O4 with in situ coated conductive carbon (C-Mn3O4). The C-Mn3O4 shows a large capacity and good cycling stability. When assembled into anodes, this material delivered a capacity of 703 mA h g–1 in a 1000 mA g–1 cycling test after 700 cycles with only a 3% capacity decay. Meanwhile, the system provided superior rate performance with capacities of 860, 823, 760, 674, and 570 mA h g–1 at 100, 200, 500, 1000, and 2000 mA g–1, respectively. On the basis of our systematic investigations, we attribute this high electrochemical performance to the carbon reinforced porous hierarchical sphere structure.