Traditional liquid lithium-ion batteries will not be the technological endpoint for power batteries. As is well known, energy density is the primary performance indicator for power batteries. With my country's electric vehicle market shifting from "policy-driven" to "policy-supported," policy guidance for improving lithium-ion battery energy density is clear. By 2025 and 2030, the energy density of single-cell power batteries in my country needs to reach 400Wh/kg and 500Wh/kg respectively. This technical indicator is already close to the ceiling of traditional lithium-ion battery energy density. Simultaneously, with the growth in electric vehicle sales, the frequency of safety accidents such as spontaneous combustion and explosions has also increased significantly. The flammable liquid electrolyte used in traditional lithium-ion batteries is largely to blame for this. In terms of energy and safety performance, current lithium-ion battery technology still has enormous room for improvement; traditional liquid batteries will certainly not be the technological finality.
Solid-state batteries are the inevitable path forward in the post-lithium battery era. Solid-state batteries refer to lithium-ion batteries that use solid-state electrolytes. In terms of performance, the non-flammable solid-state electrolyte is the core of solid-state batteries. Solid-state batteries eliminate safety hazards while increasing battery energy density. Regarding development difficulty, new types of batteries such as lithium-sulfur and lithium-air batteries require a complete overhaul of the battery structure, while the core of solid-state batteries lies in the solid-state electrolyte, making the upgrade path simpler and more convenient. Furthermore, both lithium-sulfur and lithium-air batteries use metallic lithium as the anode, and metallic lithium anodes are more easily compatible with solid-state electrolytes. Therefore, solid-state batteries also serve as a transitional platform for lithium-sulfur and lithium-air batteries. Looking at future technological directions, solid-state batteries have become an inevitable path, and their status as the next-generation battery technology closest to us has become a consensus in the scientific and industrial communities.
Industrialization is still in its early stages, but rapid development is expected in the future. The low ionic conductivity and high interfacial impedance of solid-state electrolytes limit the energy density and rate performance of batteries, and there are currently no sufficiently mature commercial products. Based on the choice of electrolyte materials, solid-state batteries can be divided into three main categories: polymer systems have the most mature technology, but their performance limits restrict development; among oxide systems, thin-film batteries face challenges in capacity expansion and large-scale production, while non-thin-film batteries offer superior overall performance and are currently a hot development area; sulfide systems are in a polarized situation of huge development potential and immature technology. In summary, although each type of solid-state battery system has challenging problems to overcome, the performance of current laboratory products already shows considerable potential, and with global capital investment and the multi-pronged approach of leading automakers, solid-state battery technology is expected to experience rapid development.
With a step-by-step, phased approach, the path of solid-state battery development is clear. Looking ahead, solid-state batteries will follow a phased development path, progressing steadily in technology and gradually penetrating applications. The battery structure will gradually reduce the use of liquids, moving towards liquid-free all-solid-state batteries. In terms of applications, they are expected to initially leverage their safety and flexibility advantages in micro-battery fields where cost sensitivity is lower, such as RFID, implantable medical devices, and wireless sensors. With technological advancements, they will gradually penetrate high-end consumer electronics. Finally, once the products are sufficiently mature, they will ultimately enter the electric vehicle and energy storage markets, achieving a full-scale explosion in downstream demand.