TOKYO - Japan’s leading industrial and electronics firms are accelerating efforts to commercialize next-generation batteries, with Toyota, Toshiba, TDK, and China’s CATL unveiling advanced technologies that promise breakthroughs in performance, safety, and supply chain resilience.
At the center of this technological race is the solid-state battery, a next-generation lithium-ion battery that replaces the flammable liquid electrolyte with a solid material, significantly enhancing safety and energy density. Toyota and energy company Idemitsu Kosan have agreed to jointly develop and mass-produce a sulfide-based solid electrolyte, aiming for practical use in electric vehicles by as early as 2027. The companies cite the material’s superior ion conductivity and flexibility as key advantages, though challenges such as durability and moisture sensitivity remain.
According to French research firm Knowmade, global patent filings for solid-state batteries have surged over the past five years, with China rapidly catching up to Japan in filings. At the Japan Mobility Show, Nissan also unveiled a concept vehicle equipped with solid-state batteries, underscoring growing momentum across the industry.
A recently published review paper titled "A Roadmap for Solid-State Batteries" summarizes over 300 scientific papers and outlines current hurdles in scaling the technology. Among the major obstacles is identifying a solid electrolyte that meets all required properties—high ion conductivity, mechanical stability, and chemical safety. Toyota and Idemitsu believe their sulfide-based electrolyte strikes the right balance, particularly due to a new flexible solid electrolyte that resists cracking and ensures longer cycle life. This development, they say, brings their batteries closer to meeting commercial durability standards.
However, sulfide-based materials are known to react with moisture, producing toxic hydrogen sulfide gas. Idemitsu claims its materials are highly water-resistant, reducing safety concerns. Still, the company acknowledges the need for further development and safe handling protocols during production. If realized, this could lower manufacturing costs by eliminating the need for water-free environments or inert gases like argon during assembly.
Toyota clarified that the solid-state battery is only one of four battery types it is pursuing, with other technologies such as bipolar lithium-ion batteries also under development. The company emphasized that while solid-state batteries are a strategic pillar, they are not a make-or-break bet. Cooperation with Panasonic remains in place through their joint venture PPES, which may eventually manufacture solid-state batteries once mass-production technology matures.
Meanwhile, Toshiba has unveiled a new lithium-ion battery called LNMO, which uses lithium, nickel, manganese, and oxygen in its cathode. The battery can charge to 80% in five minutes and endure more than 6,000 charge-discharge cycles. Crucially, it does not use cobalt or other rare metals, potentially reducing costs and supply risks. Toshiba addressed a long-standing issue with LNMO—gas generation during charging—by modifying the cathode surface and adding a special membrane to the anode, thereby preventing electrolyte decomposition.
According to Toshiba, the breakthrough stems from in-house research conducted under an “under-the-table” system that allows employees to dedicate part of their work hours to exploratory research. The LNMO project reportedly began as a side effort but showed enough promise to warrant full-scale development.
Another innovation comes from TDK, which announced it had developed a solid-state battery with a volumetric energy density of 1,000 Wh/L using a lithium alloy anode. The company emphasized that the battery is intended for small devices such as wireless earbuds and smartwatches, not electric vehicles. While the battery achieves a high energy density and safety by eliminating flammable liquid electrolytes, its ceramic-based solid electrolyte is fragile and unsuitable for automotive applications that require high durability.
Still, TDK’s solid-state battery marks a significant step forward in miniaturized energy storage, with analysts highlighting potential adoption in EU markets where regulations are pushing for longer-lasting, environmentally friendly batteries in wearables and other portable devices.
China’s CATL, the world’s largest battery manufacturer, is taking a different approach. In April 2025, the company announced it would begin mass production of the world’s first sodium-ion batteries within the year. Sodium is over 1,000 times more abundant than lithium and more evenly distributed globally, reducing geopolitical and supply-chain risks.
The latest sodium-ion batteries achieve an energy density of 175 Wh/kg, similar to existing LFP (lithium iron phosphate) batteries, with potential to increase to 200 Wh/kg in the future. CATL claims these batteries offer “inherent safety” due to their thermal stability and low risk of short-circuits. The self-heating temperature of sodium-ion cells is 260°C—significantly higher than that of lithium-ion batteries—and the softness of sodium reduces the likelihood of dangerous dendrite growth.
Despite these advantages, experts caution that sodium-ion batteries are not yet cost-competitive with LFP batteries, especially when considering materials and manufacturing infrastructure. A January 2025 study analyzing over 6,000 pricing scenarios concluded that sodium-ion batteries will match lithium-ion costs in only about 40% of cases by 2030.
Nevertheless, sodium-ion batteries may find their niche in applications where cost, safety, and sustainability are more critical than high energy density. CATL also announced two additional technologies: a battery that enables 520 km of driving range on just five minutes of charging and a “dual-power” pack that combines different chemistries to optimize both charging speed and driving range. Analysts suggest this hybrid approach could compete with plug-in hybrids by offering specialized batteries for both daily commuting and long-distance travel.
Across the board, these announcements indicate that the global battery industry is entering a new phase of innovation. Whether it’s solid-state, LNMO, lithium alloy, or sodium-ion, companies are pursuing diverse strategies to break through the limitations of today’s batteries. The future of electric mobility may depend on which of these bets pays off first.
Source: テレ東BIZ
