According to recent public media, following the establishment of a 10Ah solid-state battery performance verification platform in April this year, CATL (Contemporary Amperex Technology Co., Limited) has recently started the verification of 20Ah all-solid-state battery samples.
CATL has increased its R&D investment in solid-state batteries this year. It is reported that in the first quarter of this year, CATL introduced dozens of technical experts from solid-state battery startups and the Chinese Academy of Sciences, and has expanded its solid-state battery R&D team to over 1000 people.
If CATL can solve the safety and performance challenges on the 20Ah samples, it will enter the exploration phase of production technology and manufacturing engineering for solid-state batteries.
CATL is currently focusing on the sulfide electrolyte route. In April this year, CATL's Chief Scientist, Wu Kai, disclosed that CATL has made progress in the technologies of cathode and anode materials, processes, and manufacturing equipment for solid-state batteries, and may have the opportunity to produce solid-state batteries in small batches by 2027. However, solid-state batteries are still in the early stages. CATL stated that if a 1-9 scale represents the maturity level of solid-state batteries, the current maturity level of CATL's solid-state batteries is at level 4, with the goal of reaching level 7-8 by 2027, and hopes to achieve small-scale production of solid-state batteries.
The government is also increasing its R&D investment in solid-state batteries. On May 29, China Daily reported that China may invest about 6 billion yuan in the R&D of solid-state batteries, including six companies: CATL, BYD, FAW, SAIC, Welion New Energy, and Geely, which may receive government support for basic R&D. The government's goal is to achieve small-scale mass production of solid-state batteries by 2027.
Currently, there are several technical routes for solid-state batteries, including sulfides, oxides, polymers, and halides, but all have technical shortcomings, such as sulfide electrolytes being prone to produce toxic gases, polymer electrolytes requiring high-temperature environments, and oxide electrolytes having low conductivity, etc.
Xu Jinmei, CTO of CATL's Energy Storage Division, recently stated at an industry conference that there are four major core technical challenges with sulfide solid-state electrolytes.
Firstly, the challenges brought by the solid-solid interface. This includes the contact between the cathode and anode and the separator, the contact between active materials, and the contact issues brought by expansion and contraction. The solid-solid interface resistance formed between the sulfide electrolyte and the electrode is higher, which may hinder the transmission of lithium ions. The thin solid-state electrolyte is also prone to cracks and defects, leading to increased impedance and capacity decay.
Secondly, the dendrite and polarization issues. The compatibility of materials is poor due to the solid-state medium and solid-solid interface, especially for the stability of metal lithium. Solid-state batteries are prone to uneven deposition during the charging process, leading to the generation of dendrites and the destruction of the internal structure of the solid-state battery. During the discharging process, due to the slow diffusion of lithium, voids and polarization phenomena are prone to occur, affecting the battery performance and service life.
Thirdly, the chemical stability and cost issues of solid-state electrolytes. Sulfide solid-state electrolytes are prone to chemical reactions when in contact with water molecules in the air, leading to the loss of electrolytes and a decline in battery performance. In terms of cost, the current cost of sulfide solid-state electrolytes exceeds 40,000 yuan/ton, far higher than the cost of the electrolytes currently used in the mainstream market.
Fourthly, the matching of core processes and equipment issues. At present, solid-state batteries face the issue of performance decay in wet processes, and the dry process has issues with the dispersion and uniformity of the film. Overall, the manufacturing process for solid-state batteries is not mature. Due to the complex synthesis process and the high requirements for equipment and environment, such as high-temperature reduction methods that require high temperatures and are prone to producing harmful gases. At the same time, there are also challenges in the efficient densification and shaping of the battery core, with the internal structure of the solid-state battery core having pores and defects, low density, and short circuits caused by pressure on the edges of the electrodes.
However, according to Wu Kai's statement, CATL has found ways to solve these challenges at the 10Ah sample stage.
For example, to address the solid-solid interface issues between the cathode, anode, and electrolyte, CATL has improved the interface structural stability through single-crystal cathode multi-level full encapsulation technology, which allows the electrolyte to remain stable even in a dew point environment of -40°C. The contact interface between the cathode, anode, and solid-state electrolyte relies on a self-developed gradient-designed multi-functional composite binder to build an efficient and stable electrode conductive network, accelerating ion mobility and improving conductivity. In addition, to make the solid-state electrolyte contact more closely with the solid cathode and anode, CATL's current R&D equipment can apply a uniform pressure of 500Mpa to the battery, which is 5 times the pressure at the deepest point of the Mariana Trench, allowing the cathode and anode materials to be more closely squeezed together. To solve the lithium dendrite issue, by using a phase change self-filling technology for the lithium metal anode, materials that can flexibly change their volume and shape are used to automatically fill the gaps where lithium dendrites may grow, while alloy metals are used to change the philithicity of the cathode and anode surfaces, allowing lithium to deposit evenly on the surface, enhancing the electrolyte structure and suppressing the growth of lithium dendrites. In terms of preparation environment, CATL has improved the preparation environment for sulfide electrolytes from the industry's common -60°C dew point to a -40°C dew point environment. By designing reversible amphiphilic molecular hydrophobic layers to improve air stability and developing new material synthesis routes and low-lithium content materials to reduce costs. In addition to material improvements, CATL has also made certain breakthroughs in manufacturing technologies such as dry electrode and isostatic pressing integrated forming.
According to public information, CATL's solid-state battery cathode specific capacity can reach 230mAh/g, and the cycle life has been improved to 6000 times. However, according to industry insiders, CATL is currently unable to stabilize the cathode capacity, which fluctuates, causing the battery's power to continuously fluctuate during use. If cost is not considered, CATL is expected to achieve a mass production scale of about 0.5 GWh in 2027, which can equip thousands of electric vehicles.
In addition to CATL, several companies in the industry have recently announced the latest progress in solid-state batteries:
On November 5, a sulfide solid-state battery invention patent applied by Huawei was published by the National Intellectual Property Administration, which shows that the disclosed doped sulfide material can be used as a sulfide solid-state electrolyte in lithium-ion batteries, extending the service life of the batteries.
On November 7, Talent New Energy and Changan Automobile jointly released the separator-free semi-solid lithium battery technology, reducing the raw material cost by 10%, improving production efficiency and enhancing battery safety.
On November 8, GAC Group stated on the interactive platform that the company has initially established a full-process manufacturing process for solid-state batteries and is expected to equip vehicles by 2026.
On October 23, European car manufacturer Stellantis and American solid-state battery company Factorial Inc. jointly announced that they will launch the all-new Dodge Charger Daytona electric vehicle model equipped with Factorial's FEST® solid-state battery in 2026.
On October 23, QuantumScape, invested in by Volkswagen Group, announced that it has started small-scale production of its first batch of 5 Ah B-sample anode-free solid-state lithium metal batteries QSE-5 B for testing by automotive industry customers.
As early as September, Sunwoda (300207.SZ) has completed the development of the first generation of semi-solid batteries. Gotion High-Tech (002074.HK) claimed that its R&D of the car-grade solid-state battery "Golden Stone Battery" plans to conduct small-scale vehicle experiments in 2027 and mass production in 2030. In addition, many car manufacturers and EV battery manufacturers, including Chery, SAIC, Toyota, Nissan, BYD, BMW, EVE Energy, CALB, Welion New Energy, Samsung, and Great Power, have made progress and plans in the field of solid-state batteries.
