The Stanford University team invented a "super" battery, which has six times the power storage capacity of ordinary batteries. The mobile phone can last for a long time by only charging it once a week.

 　　Recently, the Stanford University team has developed a "high-energy storage" rechargeable battery that can last for a long time by charging mobile phones only once a week. The research results are expected to solve the pain points of smart phones that have to be charged almost every day. In terms of electric vehicles, electric vehicles can travel 6 times the daily distance without charging.

　　This kind of "high energy storage" rechargeable battery is essentially a new type of alkali metal chloride battery, and its principle is mainly through repeated reversible chemical reactions of sodium chloride or lithium chloride. The reason why the battery has long-lasting battery life is that its stored power is 6 times that of batteries currently on the market.

　　Up to now, the commercial lithium-ion battery capacity on the market is 200 mAh per gram, while the "super" battery developed by the team has a capacity of 1200 mAh per gram. Take a step forward.

　　Related papers were published on Nature with the title "Rechargeable Na/C12 and Li/C12 batteries". Zhu Guanzhou, a doctoral student in the interdisciplinary field of chemistry and biology at Stanford University, serves as the first author, and Professor Dai Hongjie serves as the corresponding author.

Related papers

　　Currently, there are many different types of rechargeable batteries on the market, including lithium ion batteries, sodium ion batteries and aluminum ion batteries. Because primary lithium-thionyl chloride batteries have many advantages in energy storage, they are widely used in professional electronics, military, utility metering and GPS tracking, but their shortcomings are also obvious, that is, they have poor rechargeability.

　　However, no scientists have developed high-performance, rechargeable chlorine-sodium batteries or lithium-chlorine batteries. The main challenge is that the chemical properties of chlorine are too active and reactive, and it is difficult to generate high-efficiency chlorides. In a few cases, other rechargeable batteries have poor battery life.

　　"Intentionally planting flowers but not blooming, unintentionally inserting willows and willows to create shade", the team did not initially plan to develop a rechargeable sodium-lithium chloride battery, but hoped to improve the technical performance of the existing sulfur-based chloride battery. Sulfur-based chloride is one of the main components of lithium chloride batteries. As early as the 1970s, it became a popular disposable battery.

　　With the development of the times, batteries with low weight, small capacity, low energy density and small size are increasingly unable to meet the ever-increasing demand for energy storage in society.

　　The traditional battery is discharged by lithium anode oxidation and catholyte thionyl chloride reduction to sulfur (SOC12), sulfur dioxide and chloride ion (Cl-). Cl- reacts with Li+ stripped from the lithium negative electrode to form lithium chloride (LiCl) deposited on the carbon surface until passivation.

　　The team observed in early experiments involving chlorine and sodium chloride that the substitution between one chemical substance and another can be stabilized in some form, and these stabilized substances are rechargeable. Dai Hongjie said: "I think this is impossible. It took us more than a year to really study the chemical reaction inside."

The first discharge principle of Na/Cl2 battery

　　Nowadays, sodium batteries have been actively sought as a substitute for lithium batteries. The scientific community believes that low-standard sodium electrode potential and high energy density batteries have broad application prospects. The research results report the use of amorphous carbon nanospheres (aCNS) and aluminum trichloride (AlCl3) in SOCl2 as the cathode and anode starting electrolytes, which are the main components in sodium-chlorine batteries.

　　The battery can be cycled for more than 200 times at a discharge voltage of 3.5V and a capacity of up to 1200mAh, and the coulombic efficiency and energy efficiency are greater than 99% and 90%, respectively. When the battery is discharged for the first time, the capacity can reach 2800mAh, and the average discharge voltage is close to 3.2V. To the surprise of the team, the battery can be reversibly cycled at a specific capacity of 1200mAh, and the average coulombic efficiency is greater than 99% at a discharge voltage of about 3.55V.

　　The team constructed a battery using sodium metal as the negative electrode, and wrapped aCNS in a nickel foam with a Teflon binder as the positive electrode in the coin cell.

　　In the next few years, the team tried to use different materials to improve the reaction efficiency of the battery's positive electrode. The biggest progress was the formation of electrodes using porous carbon materials that were co-studied with Chung Cheng University in Taiwan. The nanosphere structure of the carbon material has many ultra-tiny pores, just like a sponge, it can generate a large number of other contact chlorine molecules, and store them, and can generate salt in the subsequent reaction process.

　　Nowadays, sodium batteries have been actively sought as a substitute for lithium batteries. The scientific community believes that low-standard sodium electrode potential and high energy density batteries have broad application prospects. The research results report the use of amorphous carbon nanospheres (aCNS) and aluminum trichloride (AlCl3) in SOCl2 as the cathode and anode starting electrolytes, which are the main components in sodium-chlorine batteries.

SEM image of sodium electrode after cycling in the battery

　　The battery can be cycled for more than 200 times at a discharge voltage of 3.5V and a capacity of up to 1200mAh, and the coulombic efficiency and energy efficiency are greater than 99% and 90%, respectively. When the battery is discharged for the first time, the capacity can reach 2800mAh, and the average discharge voltage is close to 3.2V. To the surprise of the team, the battery can be reversibly cycled at a specific capacity of 1200mAh, and the average coulombic efficiency is greater than 99% at a discharge voltage of about 3.55V.

　　The team constructed a battery that uses sodium metal as the negative electrode, and uses a polytetrafluoroethylene (PTFE) binder in nickel (Ni) foam to package aCNS as the positive electrode in a coin cell.

　　In the next few years, the team tried to use different materials to improve the reaction efficiency of the battery's positive electrode. The biggest progress was the formation of electrodes using porous carbon materials that were co-studied with Chung Cheng University in Taiwan. The nanosphere structure of the carbon material has many ultra-tiny pores, just like a sponge, it can generate a large number of other contact chlorine molecules, and store them, and can generate salt in the subsequent reaction process.