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Solid-state batteries have been gaining popularity recently.
On the evening of April 8, Zhiji Automobile held a technology conference, and the protagonist was Zhiji L6, which won the attention of the industry with its "first mass production of ultra-fast charging solid-state batteries".
"The Zhiji L6 Max Light-Year Edition model is equipped with the first-generation light-year solid-state battery, which has the characteristics of high safety performance, non-explosive battery, high energy density, and high battery life. Liu Tao, co-CEO of Zhiji Automobile, said at the press conference.
At the same time, Liu Tao also revealed that the pre-sale price of the Zhiji L6 Max light-year version model equipped with solid-state batteries will not exceed 330,000 yuan, which has also triggered widespread discussions in the industry.
Image source: Zhiji Auto's WeChat public account
In fact, solid-state batteries have attracted much attention because they have significant advantages in safety and endurance compared to liquid batteries. For example, the energy density of lithium iron phosphate batteries is generally 100Wh/kg~160Wh/kg, and the energy density of ternary lithium batteries is usually 150Wh/kg~250Wh/kg. Vehicles with an energy density of 270Wh/kg~320Wh/kg can run about 600 kilometers ~ 700 kilometers on a single charge. For example, the solid-state battery mounted on the Zhiji L6 Max Lightyear Edition has a single energy density of 368Wh and a range of up to 1,000 kilometers.
"The biggest advantage of solid-state batteries is safety. Since solid-state batteries use a solid-state electrolyte, there is no risk that the liquid electrolyte will easily burn and explode. The increased safety also leads to an increase in the energy density of the battery pack, as it reduces the space and weight reserved for safety considerations. On April 8, Mo Ke, the founder of True Lithium Research, said in an interview with a reporter from the "Daily Economic News".
From liquid batteries to semi-solid-state and solid-state batteries, the core is the change of electrolyte. This change requires changes in chemical materials to increase energy density and improve safety performance, and this change is not easy either in terms of technology or manufacturing process. Because of this, the industry generally predicts that by 2030, solid-state batteries can truly achieve mass production.
It is based on this that while Zhiji Auto has earned enough eyeballs, it is also facing the torture of "innovation or gimmick".
The range of the Zhiji L6 solid-state battery version exceeded 1,000 kilometers
At the press conference, Liu Tao announced that the first-generation solid-state battery of Zhiji L6 was officially named "light-year solid-state battery". Zhiji said that the Zhiji L6 will be equipped with an ultra-fast charging solid-state battery, with the help of which the Zhiji L6 will "exceed 1,000 kilometers of ultra-long range".
In fact, in recent publicity, the Zhiji L6 has been using "the industry's first mass-produced ultra-fast charging solid-state battery" as an important promotional point. This has also attracted relevant doubts in the industry.
Not long ago, Zhao Changjiang, general manager and chief co-creation officer of DENZA Automobile, posted on Weibo that "at this time, the promotion of semi-solid vehicle batteries is playing with words." However, the Weibo has now been deleted. In response, Liu Tao said, "Word games are not what Zhiji Auto is good at, and Zhiji must practice it with practical actions."
Image source: Sina Weibo
There is so much controversy about "solid-state batteries", which may have something to do with its technology and manufacturing difficulties. "At present, the solid-state batteries (on the market) are basically semi-solid-state batteries, and the manufacturing process is not much different from the existing liquid system. Liu Yanlong, business director of the China Chemical and Physical Power Industry Association, told reporters.
Mo Ke, the founder of True Lithium Research, also said that the solid-state battery carried by Zhiji Automobile is actually a semi-solid-state battery. "[The battery] still uses electrolyte, and in the normal concept, a (full) solid-state battery should no longer use electrolyte. Mo Ke said.
This may mean that, strictly speaking, the battery on the Zhiji L6 is still a semi-solid-state battery, and a solid-state electrolyte is used instead of a partial liquid electrolyte, and the energy density of the semi-solid-state battery has been significantly improved, thereby increasing the vehicle's range.
However, in Liu Tao's view, although "Light Year" is the first generation of solid-state batteries, it has achieved more than 30% of the power with almost the same weight and a range of 1,000 kilometers, which is the value of solid-state batteries instead of liquid batteries. "Our battery can be charged in 12 minutes, and the range can be increased by 400 kilometers. Liu Tao said.
Cost is still a problem to be solved in the commercialization of solid-state batteries
"The process and equipment for all-solid-state batteries will change dramatically, and the production equipment at the front end of the battery may need to be redeveloped. Liu Yanlong believes that all-solid-state batteries are different concepts from semi-solid-state batteries and liquid batteries, and all-solid-state batteries will be applied on a large scale in vehicles until about 2030.
From a technical point of view, "ionic conductivity" is a problem that solid-state batteries have always needed to break through. It is reported that the function of the electrolyte in the battery is to build a channel for the transmission of lithium ions between the positive and negative electrodes, and the index that determines whether the lithium ion transportation is smooth is called ion conductivity.
"In solid-state batteries, lithium ions are mainly conducted by solid substances. The quality of conduction is closely related to the density of the solid substance, and the denser the conduction, the better. A battery industry practitioner told reporters.
Orient Securities Research Report believes that at the interface between the electrode and the electrolyte, the contact mode between the traditional liquid electrolyte and the positive and negative electrodes is liquid-solid contact, the interface wettability is good, and there will be no large resistance between the interface, while the solid-solid electrolyte and the positive and negative electrodes are in contact with the solid-solid interface, the contact area is small, the tightness is poor, and the ionic conductivity is usually two orders of magnitude lower than that of the liquid electrolyte. This feature leads to limited fast charging performance of solid-state batteries.
It is worth mentioning that the Zhiji L6 Max Light-Year Edition can achieve 900v fast charging, how can this be achieved? According to a Zhiji Automobile staff, the first-generation solid-state battery of Zhiji Automobile is through material optimization and some patented production processes, so that the density of solid substances is improved, and the ion conductivity will be relatively better.
Image source: Screenshot of the press conference
Aside from technological breakthroughs, cost is also an important reason hindering the large-scale implementation of solid-state batteries. Qin Lihong, president of NIO, once said during the ET7 semi-solid-state battery test that the cost of a 150kWh solid-state battery pack is close to that of a NIO ET5, that is, more than 290,000 yuan.
In Moke's view, the main challenge facing the development of semi-solid-state batteries lies in how to reduce the cost to an appropriate level. Although the technical mass production is not a big problem, the cost of semi-solid-state batteries is still high. If only the electrolyte is partially replaced with a solid state, the cost may be 30%~40% higher than that of a liquid battery, or even more.
2024 will be an important development node for solid-state batteries
Under the challenges of technology and cost, solid-state battery technology is currently showing a trend of progressive development.
On March 26, Li Zheng, general manager of Qingtao Energy, said in the live broadcast room that the industrialization of Qingtao Energy's solid-state battery is divided into three steps: the first-generation solid-state battery, which is planned to be installed and mass-produced on Zhiji Automobile, also known as the semi-solid-state battery, the second-generation solid-state battery will be developed in 2025, and the third-generation solid-state battery will be finally realized, which is the all-solid-state battery.
Moke also believes that the development of (solid-state battery) technology is a gradual process, and it is difficult to achieve leapfrog development.
"The development of solid-state battery technology can be divided into three phases: the first stage is to change the electrolyte from a liquid to a solid state, while eliminating the separator, but the cathode and anode material systems remain the same, the second stage is to replace the anode material with lithium metal, thereby significantly increasing the energy density of the battery, and the third stage is to replace the cathode material and use a high-density material that does not contain lithium ions. Moke believes that the energy density of solid-state batteries (cells) in the first stage is expected to reach 400Wh/kg, and the second stage can reach 560Wh/kg or even 700Wh/kg, and the energy density of more than 700Wh/kg should belong to the third stage.
Although the development of solid-state batteries will take time, they are still considered to be the mainstream direction of next-generation battery technology. Up to now, many car companies have a clear timetable for the time when solid-state batteries will be "on the car". For example, BMW has pledged to launch a prototype electric vehicle equipped with an all-solid-state battery by 2025 and mass production by 2030, Toyota will mass-produce solid-state batteries in 2027, Volkswagen has said that it is actively developing all-solid-state battery technology with the goal of mass production by 2025, and NIO expects to achieve mass production of semi-solid-state battery vehicles in 2025 and plans to install it on the ET7 model.
Image source: Courtesy of the company
In addition, power battery companies are also actively exploring solid-state battery technology routes. For example, recently, Tailan New Energy said that it has made significant progress in the research and development of "automotive-grade all-solid-state lithium batteries", and has developed a solid-state lithium metal battery that meets the vehicle-grade standard and has a single capacity of up to 120Ah, and the measured energy density has reached a record 720Wh/kg.
According to the latest forecast report of the well-known research institute GGII, 2024 will be an important node in the development of the solid-state battery industry, and the large-scale loading and application of (semi-)solid-state batteries is expected to be realized during the year, and the total installed capacity of the year is expected to historically exceed the 5GWh mark.