Substrate-induced coagulation (SIC) of nano-disperse carbon black in non-aqueous media: a method of manufacturing highly conductive cathode materials for Li-ion batteries by self-assembly

Abstract

Substrate-induced coagulation (SIC) is a coating process based on self-assembly for coating different surfaces with fine particulate materials. The particles are dispersed in a suitable solvent and the stability of the dispersion is adjusted by additives. When a surface, pre-treated with a flocculant e.g. a polyelectrolyte, is dipped into the dispersion, it induces coagulation resulting in the deposition of the particles on the surface. A non-aqueous SIC process for carbon coating is presented, which can be performed in polar, aprotic solvents such as N-Methyl-2-pyrrolidinone (NMP). Polyvinylalcohol (PVA) is used to condition the surface of substrates such as mica, copperfoil, silicon-wafers and lithiumcobalt oxide powder, a cathode material used for Li-ion batteries. The subsequent SIC carbon coating produces uniform layers on the substrates and causes the conductivity of lithiumcobalt oxide to increase drastically, while retaining a high percentage of active battery material.

Chemical delithiation and exfoliation ofLixCoO2

“…11, 12, and 13 , respectively, and the obtained parameters are summarised in Table 2 . The crystal structure is also consistent with data for the material “Selectipur” (Merck) described in [14,26] .…”

Preparation and characterization of core–shell battery materials for Li-ion batteries manufactured by substrate induced coagulation

“…The Substrate Induced Coagulation (SIC) coating process provides a self assembled and almost binder free coating with small particles. Most research so far has been used to coat a variety of surfaces with highly conductive carbon blacks [34,35,36] . Layers deposited by this technique have been used in electromagnetic wave shielding, in the metallization process of through-holes in printed wiring boards, and in the manufacture of conducting polymers (such as Teflon) [37,38,39] .…”

“…Recently, a non-aqueous SIC coating process of carbon black was developed by investigating the stabilities of non-aqueous dispersions [36] . These dispersions were used to prepare LiCoO 2 -composite electrodes for Li-ion batteries with an improved conductivity while keeping the content of active battery material high [35] .…”

Carbon Nanomaterials Used as Conductive Additives in Lithium Ion Batteries

“…(2a), the supply of electrons to this spot will be reflected in additional polarization, and thus, in a lower reversible capacity. The similar work was also done by Basch et al [12]. LiCoO 2 was added to Polyvinylalcohol (PVA)/NMP solution and stirred for 5 min.…”