Stimulate the maximum potential! Lithium supplements pry open the battery "ceiling"

In order to further improve the comprehensive performance of batteries, many battery giants are increasing their investment in lithium replenishers. According to the announcement of the State Intellectual Property Office, in April this year, CATL obtained an international patent application entitled "Positive electrode lithium replenishment material and preparation method, positive electrode sheet, secondary battery and power device"; and EVE Energy obtained a patent entitled "A negative electrode sheet chemical lithium replenishment device and lithium replenishment method thereof".

"In the present invention, the chemical lithium replenishment device for the negative electrode sheet uses a chemical lithiation reagent to replenish lithium, which can avoid the risk of local lithium precipitation of lithium ions during the charging and discharging process, compensate for the loss of SEI film during the first charging process of graphite and graphite/silicon composite electrode sheets, and greatly improve the safety performance of the lithium replenishment technology during the manufacturing process, the initial efficiency and energy density of the battery , and can realize the chemical batch lithium replenishment production of the negative electrode." This is how the patent abstract of Yiwei Lithium Energy is described.

In addition, BYD has applied for a patent called "lithium supplement additive and its preparation method and application". It is reported that the additive can not only quickly remove active lithium and replenish the lithium loss during the first charge, but also the coating layer of the additive is a polymer containing amidoxime groups, which has a strong chelating ability for transition metal ions, thereby greatly reducing the risk of transition metal element dissolution, so that the battery has good cycle performance, rate performance and safety performance.

"From the perspective of lithium battery technology development trends, extending battery life and reducing capacity attenuation are important technological breakthroughs . Lithium replenishment technology is becoming an effective means to solve these problems," said an industry insider. According to data predicted by research institutions, the global lithium replenisher market size will reach approximately US$2.4 billion by 2029, with a compound growth rate of 99.5% in the next few years.

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Stimulate the maximum potential of positive and negative electrodes

Lithium supplement is a functional additive. Although the amount used is not large, it can achieve a "four ounces to move a thousand gold coins" effect . It can stimulate the maximum potential of positive and negative electrode materials through precise lithium supplementation. A very small amount can effectively improve battery performance and is suitable for lithium battery materials of various systems. According to a domestic material manufacturer, adding lithium supplement can increase the energy density of the battery by more than 5% and the cycle life can be increased by 100%.

"During the charge and discharge process of lithium batteries, lithium ions migrate from the positive electrode to the negative electrode, and a part of the lithium will be embedded in the negative electrode (making it) unable to escape. At the same time, a SEI film will be formed at the negative electrode. The lithium ions inside the battery that can carry electric charge are reduced, and the battery will experience an irreversible decrease in capacity." Industry insiders analyzed that lithium supplements can effectively make up for the missing lithium ions.

According to the different methods of lithium replenishment, lithium replenishers are mainly divided into positive electrode lithium replenishers and negative electrode lithium replenishers. Positive electrode lithium replenishment usually adopts electrochemical method, by adding materials to the positive electrode to allow the battery to release active lithium through material decomposition during charging. Negative electrode lithium replenishment includes self-discharge lithium replenishment, physical lithium replenishment, chemical lithium replenishment, electrochemical lithium replenishment and other technical methods.

"It is relatively simple to add lithium to the positive electrode. It can be added during the homogenization of the positive electrode slurry, without the need for additional process improvements and at a low cost," said an industry insider. For example, lithium-rich iron oxide (LFO) and lithium-rich nickel oxide (LNO) can meet many requirements of ideal positive electrode lithium-replenishing materials . Although there are still difficulties in production, leading companies have solved them, and therefore have been the first to achieve industrial production.

However, there are currently many industrial challenges to be solved in negative electrode lithium replenishment , such as uncontrollable reactions, possible dendrite formation, chemical instability, and harsh operating conditions.

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Ningde/Evee/Sinwanda and others are competing to increase their investment

As of now, automobile companies and battery manufacturers including CATL, BYD, EVE Energy, Guoxuan High-tech, Xinwoda, BYD Power, and Zhuhai Guanyu, as well as material companies such as Defang Nano, Shenzhen Yanyi, Shida Shenghua, and Shanshan Energy have already deployed lithium replenishment technology.

As early as 2021, SAIC Zhiji's two mass-produced finalized vehicles launched globally were equipped with silicon-doped lithium-supplemented batteries jointly developed by SAIC and CATL, with a cell energy density of 300Wh/kg . In the same year, NIO released a 150kWh solid-state battery pack, using inorganic pre-lithiation silicon-carbon negative electrode technology, with a cell energy density of 360Wh/kg. In addition, Guoxuan High-tech's 210Wh/kg lithium iron phosphate battery cell uses high-gram capacity silicon negative electrode materials and pre-lithiation technology.

It is understood that the lithium supplement developed by EVE Energy contains Li2O and metal M, which are coated with the outer shell SiOx and carbon . Through the coating process, the conductivity of the material and the stability of the metal can be improved, and its dissolution can be reduced. Xinwangda uses vanadium lithium salt Li4+xV2O5 as a positive electrode lithium supplement additive, which is used in high nickel-silicon high energy density systems, significantly improving the first efficiency of the battery cell, thereby improving the energy density of the battery cell.

In terms of material enterprises, according to Defang Nano, the company has completed and put into production a lithium supplement with an annual output of 5,000 tons, and has obtained project certification from many customers at home and abroad. It has exclusive project points in energy storage, pure electric passenger vehicles, commercial vehicles, electric heavy trucks, plug-in hybrid vehicles and other application fields. It is reported that the first lithium supplement currently launched by Defang Nano is a lithium-rich lithium iron oxide positive electrode lithium supplement material with a theoretical gram capacity of more than 800mAh/g.

It is understood that Shenzhen Yanyi has developed two lithium-replenishing additives, lithium nickel-rich lithium oxide and lithium iron-rich lithium oxide, which can accurately supplement and stimulate the potential of the main electrode material system. The company has invested more than 1 billion yuan to build a 22,500-ton lithium-replenishing additive production capacity in Shenzhen. Shida Shenghua currently has a pilot production line capacity of 150 tons of lithium supplements. In February 2022, Shida Shenghua planned to invest 935 million yuan to build a 20,000-ton/year positive electrode lithium supplement project in Meishan, Sichuan.

In addition, Wanrun New Energy revealed that the company's lithium supplement product has been evaluated in a preliminary small-scale test sample, and the small-scale test capacity can reach 700mAh/g. The pilot line is currently being planned and constructed. Recently, the company obtained an invention patent called "A method for preparing a lithium supplement Li5FeO4". By mixing, grinding, spray drying, sintering and crushing the raw materials of the lithium supplement, a small-particle carbon-coated Li5FeO4 lithium supplement material is obtained.

"Lithium supplement additives are a fine chemical raw material, equivalent to industrial MSG. They account for less than 5% of the total ingredients, but they can greatly enhance the performance of battery products and even break the ceiling. " The person in charge of a domestic materials manufacturer said that with the continuous development of industry technology, lithium supplements will surely shine in the future.