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6 Nanomaterials for Batteries
The Li 2 S–C nanocomposite synthesized by the in situ composite method has a
uniform distribution in the mesoporous structure and the partially graphitized carbon
matrix. The nanocomposite method effectively suppresses the shuttle influence and
improves the cycling stability of Li 2 S (Yang et al. 2013).
6.5.5 Stability and Modification of Metal Lithium Negative
Electrode
Lithium metal is the most ideal anode material for lithium-sulfur batteries as a
result of its extremely high theoretical specific capacity (3860 mAh/g), low potential
(0.304 V), and low density (0.53 g/cm
3 ) (Cao et al. 2015). However, lithium metal
anodes also have many problems, such as the growing lithium dendrites, instability of
the solid electrolyte interface film, and almost unlimited volume expansion. Therefore, how to build a more stable lithium metal anode for lithium-sulfur batteries,
promote the smooth deposition of lithium, inhibit the growth and volume expansion
of lithium dendrites remain a challenge.
6.5.5.1 Lithium Dendrite Growth Mechanism
In lithium-sulfur secondary batteries, lithium metal needs to be continuously
deposited and stripped, and the lithium dendrite will accumulate on the electrode
surface after being reciprocated which caused many serious problems. Cations form
a concentration gradient between the positive and negative electrodes during the electrodeposition process. When the current density between the two electrodes reaches
the critical current density, the critical current will remain for a very short time
called the transition time (τ). After that, the cations in the electrolyte will decrease,
destroying the potential balance on the electrode surface. This process can lead to the
generation of local space charge on the surface of the electrode and unstable metal
deposition, thereby producing dendrites. However, SEI is generated on the metallic
surface due to the deposition and exfoliation of lithium metal. Even if the current
density is lower than the critical current density, lithium dendrite will still be generated, so the growth mechanism of lithium dendrite is more complicated and further
research is needed (Lin et al. 2017; Xu et al. 2014). The current density has a greater
influence on the growth of dendrites during lithium deposition and the growth of
lithium dendrites was accelerated under high current densities.
6 Nanomaterials for Batteries
The Li 2 S–C nanocomposite synthesized by the in situ composite method has a
uniform distribution in the mesoporous structure and the partially graphitized carbon
matrix. The nanocomposite method effectively suppresses the shuttle influence and
improves the cycling stability of Li 2 S (Yang et al. 2013).
6.5.5 Stability and Modification of Metal Lithium Negative
Electrode
Lithium metal is the most ideal anode material for lithium-sulfur batteries as a
result of its extremely high theoretical specific capacity (3860 mAh/g), low potential
(0.304 V), and low density (0.53 g/cm
3 ) (Cao et al. 2015). However, lithium metal
anodes also have many problems, such as the growing lithium dendrites, instability of
the solid electrolyte interface film, and almost unlimited volume expansion. Therefore, how to build a more stable lithium metal anode for lithium-sulfur batteries,
promote the smooth deposition of lithium, inhibit the growth and volume expansion
of lithium dendrites remain a challenge.
6.5.5.1 Lithium Dendrite Growth Mechanism
In lithium-sulfur secondary batteries, lithium metal needs to be continuously
deposited and stripped, and the lithium dendrite will accumulate on the electrode
surface after being reciprocated which caused many serious problems. Cations form
a concentration gradient between the positive and negative electrodes during the electrodeposition process. When the current density between the two electrodes reaches
the critical current density, the critical current will remain for a very short time
called the transition time (τ). After that, the cations in the electrolyte will decrease,
destroying the potential balance on the electrode surface. This process can lead to the
generation of local space charge on the surface of the electrode and unstable metal
deposition, thereby producing dendrites. However, SEI is generated on the metallic
surface due to the deposition and exfoliation of lithium metal. Even if the current
density is lower than the critical current density, lithium dendrite will still be generated, so the growth mechanism of lithium dendrite is more complicated and further
research is needed (Lin et al. 2017; Xu et al. 2014). The current density has a greater
influence on the growth of dendrites during lithium deposition and the growth of
lithium dendrites was accelerated under high current densities.