2 research outputs found
High Performance LiMn<sub>2</sub>O<sub>4</sub> Cathode Materials Grown with Epitaxial Layered Nanostructure for Li-Ion Batteries
Tremendous research works have been
done to develop better cathode
materials for a large scale battery to be used for electric vehicles
(EVs). Spinel LiMn<sub>2</sub>O<sub>4</sub> has been considered as
the most promising cathode among the many candidates due to its advantages
of high thermal stability, low cost, abundance, and environmental
affinity. However, it still suffers from the surface dissolution of
manganese in the electrolyte at elevated temperature, especially above
60 °C, which leads to a severe capacity fading. To overcome this
barrier, we here report an imaginative material design; a novel heterostructure
LiMn<sub>2</sub>O<sub>4</sub> with epitaxially grown layered (<i>R</i>3Ì…<i>m</i>) surface phase. No defect was
observed at the interface between the host spinel and layered surface
phase, which provides an efficient path for the ionic and electronic
mobility. In addition, the layered surface phase protects the host
spinel from being directly exposed to the highly active electrolyte
at 60 °C. The unique characteristics of the heterostructure LiMn<sub>2</sub>O<sub>4</sub> phase exhibited a discharge capacity of 123
mAh g<sup>–1</sup> and retained 85% of its initial capacity
at the elevated temperature (60 °C) after 100 cycles
Low-Temperature Carbon Coating of Nanosized Li<sub>1.015</sub>Al<sub>0.06</sub>Mn<sub>1.925</sub>O<sub>4</sub> and High-Density Electrode for High-Power Li-Ion Batteries
Despite their good intrinsic rate
capability, nanosized spinel
cathode materials cannot fulfill the requirement of high electrode
density and volumetric energy density. Standard carbon coating cannot
be applied on spinel materials due to the formation of oxygen defects
during the high-temperature annealing process. To overcome these problems,
here we present a composite material consisting of agglomerated nanosized
primary particles and well-dispersed acid-treated Super P carbon black
powders, processed below 300 °C. In this structure, primary particles
provide fast lithium ion diffusion in solid state due to nanosized
diffusion distance. Furthermore, uniformly dispersed acid-treated
Super P (ASP) in secondary particle facilitates lower charge transfer
resistance and better percolation of electron. The ASPLMO material
shows superior rate capability, delivering 101 mAh g<sup>–1</sup> at 300 C-rate at 24 °C, and 75 mAh g<sup>–1</sup> at
100 C-rate at −10 °C. Even after 5000 cycles, 86 mAh g<sup>–1</sup> can be achieved at 30 C-rate at 24 °C, demonstrating
very competitive full-cell performance