Abstract
Nanocomposites of Li1.4Ni0.5Mn0.5O2+x and amorphous carbon were obtained by the pyrolysis of linear and cross-linked poly(vinyl alcohol) (PVA) in presence of Li1.4Ni0.5Mn0.5O2+x. In the case of linear PVA, the formation of nanostructured carbon coatings on Li1.4Ni0.5Mn0.5O2+x particles is observed, while for cross-linked PVA islands of mesoporous carbon are located on the boundaries of Li1.4Ni0.5Mn0.5O2+x particles. The presence of the carbon framework leads to a decrease of the polarization upon cycling and of the charge transfer resistance and to an increase in the apparent Li+ diffusion coefficient from 10−16 cm2·s−1 (pure Li1.4Ni0.5Mn0.5O2+x) to 10−13 cm2·s−1. The nanosized carbon coatings also reduce the deep electrochemical degradation of Li1.4Ni0.5Mn0.5O2+x during electrochemical cycling. The nanocomposite obtained by the pyrolysis of linear PVA demonstrates higher values of the apparent lithium diffusion coefficient, a higher specific capacity and lower values of charge transfer resistance, which can be related to the more uniform carbon coatings and to the significant content of sp2-hybridized carbon detected by XPS and by Raman spectroscopy.
Highlights
LiNi0.5Mn0.5O2-based electrode materials [1] were proposed as a less expensive alternative to LiCoO2 for high energy density Li-ion batteries containing less toxic elements than cobalt
We investigated the influence of composition and micro/nanomorphology of the carbonaceous coatings obtained by the pyrolysis of various kinds of poly(vinyl alcohol) (PVA) on the kinetics of lithium intercalation–deintercalation and the electrochemical properties of Li1.4Ni0.5Mn0.5O2+x/C composites
In the case of LNM/C composites obtained from linear PVA, 5–7 nm thick carbon coatings can be clearly observed on the particle surface as well as amorphous carbon bottlenecks between particles forming a consolidated 3D network (Figure 1B)
Summary
LiNi0.5Mn0.5O2-based electrode materials [1] were proposed as a less expensive alternative to LiCoO2 for high energy density Li-ion batteries containing less toxic elements than cobalt. In the case of LNM/C composites obtained from linear PVA, 5–7 nm thick carbon coatings can be clearly observed on the particle surface as well as amorphous carbon bottlenecks between particles forming a consolidated 3D network (Figure 1B).
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