Chongqing - A Chongqing-based company has developed a "sandwich" structure for lithium batteries that addresses one of the main concerns for new energy vehicle (NEV) consumers: the risk of battery fires and explosions.

Workers on the production line at Chongqing Jimat New Material Technology Co., Ltd. (Photo provided by the interviewee)

Lithium batteries, while essential to NEVs, have faced scrutiny due to a history of fire hazards, especially during severe impacts. This occurs when traditional pure metal current collectors inside the battery rupture, forming micro-burrs that can pierce the separator and trigger a short circuit, leading to thermal runaway.

To solve this problem, Chongqing Jimat New Material Technology Co., Ltd. invested nearly a decade in research, innovating a “metal-polymer-metal” composite structure for battery current collectors. This "sandwich" design incorporates a polymer layer between metal films, which acts as a buffer during impacts. When heated, the polymer layer softens and melts, functioning as an internal fuse to prevent dangerous heat buildup. Additionally, the composite material mitigates burr formation, thus lowering the risk of explosion.

Addressing a pain point in the NEV market

Chongqing Jimat's journey to this innovation began in 2015, often referred to as the start of the NEV boom. An incident where a Samsung phone battery exploded while charging highlighted the need for safer battery materials, inspiring Jimat’s founder, Zang Shiwei, to pursue this project. Collaborating with a major industry player, Zang aimed to replace traditional aluminum and copper collectors with the new "sandwich" composite material to enhance battery safety.

The team’s first attempt, using PET as a base material, failed during testing. The material deteriorated after 500 charge-discharge cycles, far below the industry requirement of 2000 cycles. After investing over 300 million yuan (about 41.87 million U.S. dollars), Zang and his team had to rethink their approach.

Eventually, they discovered polypropylene as a viable material, offering superior impact resistance and chemical stability. This breakthrough not only solved the heat and impact issues but also reduced the composite weight by 60% and material costs by nearly 50% while increasing energy density by up to 10%.

Scaling production and aiming for global leadership

Jimat’s first generation of copper and aluminum composite collectors hit the market in late 2018, powering 30,000 electric vehicles sold in Europe. Despite the positive market response, scaling production posed its own challenges. In 2019, Jimat set up a production facility in Chongqing, investing over 1 billion yuan (about 140 million U.S. dollars) to boost its capacity.

The company faced multiple technical setbacks, especially in coating metal films onto the polymer without damaging it. Jimat had to redesign its entire production line, refining thermal and cooling processes and adjusting equipment to achieve stable production. By 2021, the factory was successfully running trials, and by 2022, the company began mass production for high-end brands like Zeekr.

In 2023, Jimat’s production line will have the capacity to produce battery materials for 10 GWh, and it plans to grow steadily. Major clients have shown strong demand, with one stating they will take 95% of Jimat's output. The company also seeks to expand into the consumer electronics, energy storage, and defense sectors.

Looking forward, Jimat aims to transform its Chongqing facility into a “lighthouse factory,” optimizing production efficiency and advancing the development of ultrathin, lightweight materials. By 2030, the global market for current collector material applications is projected to exceed 200 billion yuan (about 28 billion U.S. dollars), and Jimat plans to capture a significant share. With a target of 100 GWh annual production, the company envisions a 10 billion yuan (about 1.4 billion U.S. dollars) output, solidifying its position in the rapidly growing market.

(She Zhenfang, a reporter from Chongqing Daily, contributed the Chinese version of this report.)