The types, functions and properties of binder commonly used in lithium ion battery

I. Lithium battery binders are generally polymer compounds. Common binders in batteries are:

(1)PVA(polyvinyl alcohol)PVA molecular formula for card CH2CHOH hand JJ, the degree of polymerization "is generally 700 -- 2000, PVA is a hydrophilic polymer white powder, the density of 1, 24 -- 1.34g •cm-3. PVA can be miscible with other water-soluble polymers, such as starch, CMC, seaweed sodium and so on have good miscibility.

(2)PTFE, commonly known as "plastic king", is a white powder with a density of 2.1 -- 2.3 g•CITI+ and a thermal decomposition temperature of 415℃. PTFE electric insulation performance is good, acid resistance, alkali resistance, oxidation resistance. The molecular formula of PTFE is CF2 - CF2. Is made by polymerization of tetrafluoroethylene. nCF2 = CF, 2 one card CF2 = CF2 in. 60% PTFE emulsion is commonly used as electrode binder.

(3)  (CMC)CMC is white powder, easily soluble in water, and the formation of a transparent solution, has good dispersion ability and binding force, and has the ability to absorb water and retain water.

(4) Polyolefin (PP, PE and other copolymers);

(5) (PVDF/NMP) or other solvent systems;

(6) Modified SBR rubber with good bonding performance;

(7) fluorinated rubber;

(8) polyamine ester.

Adhesive for lithium battery; In lithium-ion batteries, due to the use of organic electrolyte with low conductivity, the electrode area is required to be large, and the battery assembly adopts coil structure. The improvement of battery performance not only puts forward new requirements for electrode materials, but also puts forward new requirements for the adhesive used in the electrode manufacturing process.

2.The  role and properties of adhesives;

(1) Ensure the uniformity and safety of the active substance during pulping;

(2) adhesion between particles of active substances;

(3) The active substance is bonded to the collecting fluid;

(4) Maintain the adhesion between the active substances and the fluid collector;

(5) It is beneficial to form SEI film on the surface of carbon material (graphite).