Lithium battery diaphragm: key inner components of lithium battery
Lithium battery consists of four main parts: positive electrode, negative electrode, diaphragm and electrolyte. Diaphragm is a kind of thin film with microporous structure. It is the key link in lithium-ion battery and the key inner component with the most technical barriers in the lithium-ion battery industry chain. The cost accounts for about 10% – 20%. When the lithium battery carries out electrolytic reaction, the lithium battery diaphragm can be used to separate the positive electrode and the negative electrode, prevent the occurrence of short circuit, and allow the free passage of electrolyte ions. The lithium battery diaphragm is soaked in the electrolyte, and there are a large number of micropores on the surface that allow lithium ions to pass through. The material, quantity and thickness of micropores will affect the speed of lithium ions passing through the diaphragm, and then affect the discharge rate, cycle life and other properties of the battery.
New energy vehicles drive diaphragm shipment growth
At present, diaphragm mainly includes two technical routes: wet diaphragm and dry diaphragm. At present, ternary material power lithium batteries basically use wet diaphragm, while lithium iron phosphate batteries that also need to continuously improve energy density also use wet diaphragm from mainstream manufacturers such as Ningde and GuoXuan. In the past few years, with the increase of the shipment proportion of ternary material power lithium battery with relatively high energy density, the shipment proportion of wet diaphragm has also increased year by year. In 2021, China’s diaphragm output was 7.9 billion square meters, a year-on-year increase of 112.5%, of which the wet diaphragm output was 6.06 billion square meters, accounting for 76.7%, a year-on-year increase of 132%; The output of dry diaphragm is 1.844 billion square meters, accounting for 23%, with a year-on-year increase of 67.7%. In the future, with the rapid growth of energy storage, it will further bring the incremental market of wet and dry diaphragm.
Diaphragm shipments increased rapidly, and wet preparation became the mainstream
In the wet diaphragm market, Yunnan Energy New Material Co.Ltd(002812) accounts for 50.3% of the market in China, and Sinoma Science & Technology Co.Ltd(002080) and Shenzhen Senior Technology Material Co.Ltd(300568) rank second and third. In the dry process diaphragm market, ZTE new materials, Shenzhen Senior Technology Material Co.Ltd(300568) and Huiqiang new materials rank among the top three. Wet diaphragm is a product with high technical barriers, high capital investment and long construction cycle. And the production equipment depends on imports, including Japan Steel Institute, Germany Bruckner, etc. The equipment of Nippon Steel is more advanced in the field of wet diaphragm, but its production capacity is limited, which can not match the increment of diaphragm demand for the great development of global new energy vehicles, which is one of the major constraints in the current production expansion. The wet diaphragm is still in short supply in 2022, and is expected to continue to maintain a high outlook.
Risk warning: downstream new energy demand is less than expected; The production capacity of lithium battery diaphragm seriously exceeded expectations.
