Secondary battery, battery pack, vehicle, and stationary power supply
摘要
說明書
The conductive agent is mixed as needed to raise current collection performance and suppress the contact resistance between the active material and the current collector. Examples of the conductive agent include carbonaceous materials such as acetylene black, Ketjen black, graphite, and coke. The conductive agent may be of one type, or two or more types may be used in mixture.
As the binder, for example, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), fluorine-based rubber, ethylene-butadiene rubber, polypropylene (PP), polyethylene (PE), carboxymethylcellulose (CMC), polyimide (PI), polyacrylimide (PAI), or the like can be used. The binder may be of one type, or two or more types may be used in mixture.
The mixing ratios of the positive electrode active material, the conductive agent, and the binder in the positive electrode active material-containing layer are preferably 70 mass % to 95 mass %, 3 mass % to 20 mass %, and 2 mass % to 10 mass %, respectively. If the mixing ratio of the conductive agent is 3 mass % or more, the conductivity of the positive electrode can be improved. If the mixing ratio of the conductive agent is 20 mass % or less, decomposition of the aqueous electrolyte on the conductive agent surface can be reduced. If the mixing ratio of the binder is 2 mass % or more, a sufficient electrode strength can be obtained. If the mixing ratio of the binder is 10 mass % or less, the insulating portion of the electrode can be decreased.
