Polymer lithium ion battery used for ultralow temperature discharging and preparing method of polymer lithium ion battery

Abstract

The invention discloses a polymer lithium ion battery used for ultralow temperature discharging and a preparing method of the polymer lithium ion battery. An anode plate is prepared from, by mass, 94.0%-96% of lithium cobalt oxide, 1.3%-2.0% of binder and 2.5%-4% of conductive agent; a cathode plate is prepared from, by mass, 94%-95.5% of mesocarbon microbeads, 1.5%-2.5% of conductive agent, 0.5%-1.5% of suspending agent and 3.0%-3.5% of acrylic resin; an isolating membrane is an oily double-sided gluing isolating membrane; electrolyte is composed of LIPF6 and solvent. At a low temperature environment of -50 DEG C, auxiliary materials in anode and cathode materials inside the polymer lithium ion battery are not vitrified, the battery can normally discharge with 0.2 C, after many times of circulation, the battery capacity conservation rate is high, and the battery is suitable for working circularly in the low temperature environment like the north of China, Russia or European areas (high-latitude areas) for a long term; the battery is high in safety and conforms to a national standard.

Description

technical field [0001] The invention relates to the field of low-temperature lithium-ion batteries, in particular to a polymer lithium-ion battery for ultra-low temperature discharge and a preparation method thereof. Background technique [0002] Polymer lithium battery (Li-polymer, also known as polymer lithium battery): it is also a kind of lithium-ion battery, but compared with liquid lithium battery (Li-ion), it has high energy density, smaller size, and ultra-thin , lightweight, and high safety and other obvious advantages, is a new type of battery. In terms of shape, lithium polymer batteries have ultra-thin features, and can be made into batteries of any shape and capacity to meet the needs of various products. Compared with liquid lithium-ion batteries, polymer lithium-ion batteries not only have higher safety, but also have the advantages of thinner shape, arbitrary area and arbitrary shape. The shell also uses a lighter aluminum-plastic composite film. However, t...

AI Technical Summary

Problems solved by technology

At this temperature, compared with normal temperature, the interior of the battery has undergone strong changes. The main reasons are: 1. The increase in the viscosity of the electrolyte leads to a decrease in conductivity, and the rate of lithium ion transfer between the positive and negative electrodes and the difficulty of intercalating lithium increase. ; 2. The auxiliary materials in the positive and negative electrode materials inside the battery are vitrified, which hinders the conduction of lithium ions (the hindrance appears in all positions of the entire pole piece, but the maximum resistance is between the main material and the current collector)

[0004] One of the existing patents is a low-temperature high-capacity polymer lithium-ion battery preparation method (ZL201610649334.0), which has a working temperature range of -40-50°C, good low-temperature performance, and can discharge about 40% at 1C at -40°C , the energy density can reach 250-255Wh / kg, but it cannot meet the low temperature use at -50°C

At the same time, lithium cobaltate is used in the positive electrode sheet of the patent. The conventional lithium cobaltate particles are relatively large, and the large particle materials form fewer ion channels between particles after rolling, and at low temperatures, these The lack of ion channels will directly lead to the decline of the conductivity of the positive electrode, which cannot meet the low temperature environment of -50°C;

[0005] At the same time, the negative electrode sheet of this patent uses ordinary graphite, while the graphitized particle size distribution of composite graphite and natural graphite is wide, resulting in a relatively small number of ion channels. In an ultra-low temperature environment, the problem of this structure is further amplified. The resulting performance is poor, and it is difficult to meet the low temperature environment of -50°C