The automotive industry is currently undergoing a transformative phase, driven by the ambitions surrounding carbon neutrality and sustainable transportation. Central to this revolution is the innovative push towards electric vehicles, where advancements in battery technology play a pivotal role. Among the various battery technologies being explored, solid-state batteries have emerged as a potential game-changer. This shift in focus is not merely about refining existing technologies; it represents a strategic move by automotive manufacturers and battery producers alike to enhance their competitive edge in the rapidly evolving market of new energy vehicles (NEVs).

As leading car manufacturers race to establish timelines for the integration of solid-state batteries into their vehicles, significant progress has been reported this year. Toyota, long regarded as a frontrunner in automotive innovation, recently unveiled its roadmap for the next generation of battery technologies. On June 28, the company announced a commitment to introduce various forms of advanced batteries, including lithium-ion, lithium iron phosphate, and a fully solid-state battery, commencing in 2026. The solid-state battery is projected to be operational by 2027-2028, aiming for remarkable performance that includes a driving range exceeding 1,000 kilometers and a fast-charging capability that allows for a full recharge in just 10 minutes.

Similarly, SAIC Motor's premium electric vehicle brand, Zhiji, has made headlines with its debut of the first near 900V ultra-fast-charging solid-state battery. This technology, known as the First Generation Light-Year Solid-State Battery, has also made its way into the Zhiji L6 sedan. Following this announcement, SAIC confirmed the construction of its first solid-state battery production line, with aims for mass production by 2026, emphasizing a polymer-inorganic composite electrolyte technology.

Guangzhou Automobile Group (GAC) has also revealed its full solid-state battery design, boasting a groundbreaking energy density of over 400 Wh/kg. This advancement surpasses traditional liquid lithium-ion batteries by more than 52% in volumetric energy density and over 50% in gravimetric energy density, paving the way for vehicles capable of exceeding 1,000 kilometers of range. GAC has set a goal to finalize the development of its solid-state battery by 2026, with plans to feature it in its Haobo model.

Contemporary Amperex Technology Co. Limited (CATL), a leading global battery manufacturer, has expressed ambitions of introducing small-scale production of solid-state batteries by 2027. However, caution is warranted, as CATL's Chief Scientist Wu Kai has pointed to the still nascent stage of development, cautioning against over-enthusiasm due to unresolved challenges related to costs and materials.

The appeal of solid-state batteries lies in their superior safety attributes, high energy density, robust power capabilities, and resilience to temperature fluctuations. These qualities have garnered international consensus on their potential to dethrone traditional lithium-ion batteries as the cornerstone of next-generation electric vehicle technology. Nations worldwide are increasing investments in research and development for what is seen as a revolutionary advancement in battery technology. A number of companies have laid out timelines leading to the industrialization of solid-state batteries around the years 2027 to 2030. For instance, South Korea's SK On has indicated it will produce prototype solid-state batteries by 2026, while Samsung SDI plans to launch a no-anode design solid-state battery by 2027, aimed at mass production.

Yet, despite the excitement surrounding solid-state batteries, there remains some confusion in the industry regarding what constitutes a true solid-state battery. Following Zhiji's announcement, several industry insiders suggested that the Light-Year battery is, in fact, a half-solid battery. This claim was corroborated by Li Zheng, co-founder of Qingtan Energy, who noted that Zhiji's design incorporates a liquid electrolyte, which differentiates it from a fully solid-state approach.

Battery technology can be classified by the liquid electrolyte content into liquid (10 wt% to 25 wt%), half-solid (5 wt% to 10 wt%), quasi-solid (0 wt% to 5 wt%), and fully solid (0 wt%). Thus, while half-solid batteries bridge the gap between traditional liquid batteries and fully solid designs, they cannot be categorized solely as solid-state batteries. This distinction has been emphasized by Cui Dongshu, Secretary General of the China Passenger Car Association, who indicates that many enterprises tend to conflate these categories in their marketing and announcements.

In the realm of solid-state technology, three predominant pathways are currently being pursued: polymer solid-state batteries, oxide solid-state batteries, and sulfide solid-state batteries. Companies from Japan and South Korea favor the sulfide route, while numerous domestic firms in China are exploring the oxide approach. Reports suggest that the majority of products being developed in China lean towards half-solid battery technologies, as domestic manufacturers leverage their existing capabilities.

Despite advances, the full realization of solid-state batteries remains elusive. According to Zeng Yuqun, Chairman of CATL, while domestic companies are prepared for mass production of half-solid batteries by 2025, the full-solid variants are still in need of breakthroughs in electrode materials and manufacturing processes, and thus will not see large-scale production within the next few years.

There is a growing dialogue in the industry emphasizing the need for caution when advancing solid-state technology. Renowned Chinese academician Ouyang Minggao has articulated the imperative of distinguishing between half-solid and fully-solid state batteries. He argues for a systematic approach toward commercializing solid-state technology, underscoring that goals should center around achieving energy densities of 300 Wh/kg and 600 Wh/L in the near term, with longer-term aspirations exceeding 500 Wh/kg and 1,000 Wh/L by 2035. Ouyang expresses a sense of urgency, stating that the timeline for true industrialization would fall between three to ten years from now.

The hurdles facing solid-state technology are quite significant. The field is currently striving to resolve the inherent scientific and technical challenges related to core materials, interfaces, and processing techniques. Specifically, sulfide electrolytes suffer from stability issues and high production costs, while silicon-carbon and lithium anodes are still regarded as immature technologies. Interface compatibility between solid components remains an ongoing concern, compounded by complexities in manufacturing that lead to high environmental control costs and low efficiency. Moreover, assessment benchmarks under actual operational conditions are still lacking standardization.

In terms of manufacturing processes, industry experts warn against a wholesale shift from traditional methods, which may require extensive equipment overhauls. This raises concerns about escalating costs and potential disruptions across the supply chain, particularly given China's established ecosystem for liquid lithium-ion batteries encompassing every stage from mining to recycling. Any transition to solid-state technology could jeopardize the competitive balance in this space.

Moreover, in discussing the trade-offs between solid and liquid battery technologies, Ouyang cautions against complacency, noting that while Japan and Europe advance solid-state technology to counterbalance China's existing advantages, China must simultaneously prioritize optimizing its liquid lithium-ion battery strategies while striving to overcome the challenges of solid-state development.