Complexation of Conductive Agents to Cathode Active Materials of Lithium-Ion Batteries Using the Poly–Ion Complex Formation Reaction

Abstract

Electrodes of lithium-ion batteries are currently deposited by the slurry method. However, in the slurry method, the materials that make up the electrodes, that is, active materials, conductive agents, and binders, are subject to problems such as segregation and aggregation. This problem can be solved by generating composite particles of the active material, the conductive agent, and the binder. Composite particles that combine these three functions can be synthesized by forming a poly–ion complex (PIC) consisting of organics containing amino groups and graphene oxide on the surface of lithium transition metal oxide, the cathode active material. The formation mechanism of these particles is discussed, and their potential as a battery material is investigated by examining the conductivity of the electrode film. The conductivity of the electrode film using these composite particles is approximately 35% higher than that of the film in which Li­(Ni0.34Co0.33Mn0.33)­O2 (NCM), carbon black (CB), and polyvinylidene fluoride (PVDF) are mechanically mixed. This is understood as a result of the direct bonding between PIC and NCM. The conductive agent and binder are highly dispersed around the NCM particles without segregation/aggregation. In addition, when a dry film is formed using only the composite particles without adding PVDF, the adhesion to the collector foil is good and the conductivity improves compared to the sample with PVDF.

Failure of Lithium-Ion Batteries Accelerated by Gravity

“…Throughout the HRAAT, the chain carbonate in the electrolyte decomposes into ROLi, which is the main component of the SEI film and corresponds to a small peak at 1000 cm –1 . In addition, three CO absorption peaks are observed at 863.5, 1430–1440, and 1510–1520 cm –1 (marked in light red), which can be attributed mainly to the Li 2 CO 3 /polycarbonate/carboxylate species, the decomposition products of the electrolyte solvent. − They are caused by the low concentration of the electrolyte at the top of the battery and the high activity of the solvent, which tends to undergo oxidation decomposition on the surface of the electrodes . Meanwhile, the top part has the highest IR among the three parts and experiences significant heat accumulation, accelerating the occurrence of side reactions.…”

Mesoporous Carbon as Conductive Additive to Improve the High‐Rate Charge/Discharge Capacity of Lithium‐Ion Batteries

“…[20][21][22][23][24][25][26][27] The commonly used conductive additives are carbon-derived nanomaterials with high specific surface area. [28][29][30][31][32] To date, Super-P with a Brunauer-Emmett-Teller (BET)-specific surface area of approximate 60 m 2 g À1 , one of the representative commercial carbon blacks, has been widely used in LIBs. [33] Super-P possesses a chain or cluster-like aggregate structure, composed of primary spherical carbon nanoparticles with a mean diameter of 35 nm.…”