2 mechanism of electrical conduction in polymer electrolyte

2.1 comb polymer conduction mechanism of electrolyte Hp laptop battery

Monte Carlo simulation of ion migration, ab initio molecular orbital calculations and the migration of lithium ion in the PEO and PPO in nuclear magnetic resonance (NMR) showed that lithium-ion polymer chain and strengthen coordination of oxygen reduces the barrier height and lead to Li-O bond length increases, thus contributing to the movement of the lithium ions. Therefore, the polymer electrolyte comb-shaped side chain has a lower Tg, but also the structure of the polymer backbone of greater individual freedom of movement, can provide more motion segments, and therefore higher conductivity. Tit O, and others [12, 18] in the comb-shaped polymer of poly (ether epoxy)-LiTFSI system believes that the lithium-ion interaction with the molecule of ethylene oxide can occur only, but also can be molecules, shown in Figure 1. Transmission speed is relatively loose intermolecular interaction, ion. However, the occurrence of intermolecular interactions, but increase rapidly intramolecular interactions Tg Tg but will not grow rapidly, but the formation of the structure, the difficulties of ion transport. Therefore, the balance between them has been high on the conductivity is very important.

2.2 The mechanism of conduction polymer electrolyte [19, 20]

hyperbranched polymers with unique molecular structure and properties of a focus on research of polymers in recent years. The highly branched structure can be effective in preventing the crystallization of chain segments, while the spherical molecular may increase the free volume of polymer, it was also concerned about the field of polymer electrolyte. Hawker et al [21] The results of SP-based hyperbranched PES, Tg and the relationship between the concentration ratio of lithium salt is classic Di Marzio, and TG-1 and the lithium salt concentration curve slope and the Nest SP and other SPE-based cross-linking is very similar to the slope.HP Pavilion DV4000 Battery(hp dv4000 battery) , HP Pavilion ZE2000 Battery(hp ze2000 battery), This shows that although not the main polymer chain, but the branching unit in the PEO chains can also interact with the lithium salt so that the dissociation of lithium and lithium-ion transport.HP Pavilion DV4000 Battery(hp dv4000 battery) , hyperbranched polymer Tg and the number of distribution units and the balance between the number of terminal units is closely related to increasing the number of terminal units, Tg decreased, increased the number of distribution units, will be in the free volume of the nuclear reduced to a rapid increase in Tg. Therefore, the electrical conductivity of hyperbranched PES influence by the parent structure.

Wen.ZY et al [22] The study suggests that star polymers multi-arm when the arm “in a longer PEO chains, such as n = 11.8, low Tg is due to the ion interaction Lithium-ethylene oxide primarily in the molecule, but when his arm “in a small number of PEO chains, such that n = 3, Tg is higher, because not enough oxygen atom of interaction lithium-ion ethylene oxide occurs mainly in the molecular. Compared with the polymer electrolyte comb-shaped, long “arms star polymer” has a higher conductivity. This is because the long “arms” star is not the main polymer chain molecules, restrictions on the movement of small arms, easily formed around the conductive base layer.

2.3 The two-phase conductive polymer electrolyte

Hikmet, RAM, etc. [23] first proposed the concept of two-phase polymer electrolyte (dual phase polymer electrolyte, DPE). Among them, one phase of its excellent mechanical support polymer electrolytes, ionic conductivity of another phase was to provide access. Recently, they designed a topology of ion conduction pathways: mixed latex DPE (latex mixed). In the emulsion mixed polarity of the latex particles, a common emulsifying agent to form an ion conductive zone, which is rich in salt solution of lithium ionic conductivity of DPE near 10-5 S cm-1. In the nucleus – shell latex DPE, the coiled polar polymer stabilizer in the nucleus of non-polar polymers, forming a shell layer of polar polymer when the polymer after the formation of the main things, the collapse of the latex particles, the party Nuclear latex support the formation of polymer mixture phase. HP Pavilion ZE2000 Battery(hp ze2000 battery),On the other hand, the region of lithium salt solution impregnation polar shell after the formation of ion conducting phase.

2.4 Composite polymer electrolyte (CPE) conduction mechanism

Polymer electrolyte by adding inorganic filler powder can improve its performance. Many scholars have discussed. Wieczorek.W [24-26], so that it is because the added inorganic filler powder inhibited the crystallization of the polymer matrix, while the polymer chains and the existence of a powder particles resulting from role. The results show that, because the powder charge is small, HP Pavilion DV4000 Battery(hp dv4000 battery) , HP Pavilion ZE2000 Battery(hp ze2000 battery), large surface, the steric inhibition of the polymer (PEO, for example) of crystallization of the chain of high disorder CSEP ion migration. September powder Ganam not increase its conductivity gradually decreased with time, while adding nano powder CSPE conductivity increases with time has also increased slightly. It may be that particles of nano-powder and SPE between a specific role. Research has shown that when the temperature is very high (above 70 ℃), CSEP of the ionic conductivity of corresponding polymer powder without addition of inorganic electrolytes still improve a lot. This can not only increase the degree of disorder due to the CSPE, because at that temperature without the addition of inorganic polymer SPE powder itself, its structure is amorphous. Croce. F [27, 28] while the system PEO8LiClO4 Lewis acid with the polarity of inorganic powder particles can be used as surface groups and PEO chain anionic cross-linking of the center, improve the rigidity the whole system and reduce the recrystallization tendency of PEO chain