Samsung Electro-Mechanics, the electronic parts manufacturing subsidiary of the chip giant Samsung Electronics, has developed the world’s first all-solid-state battery for wearable devices, industry sources said Monday.

According to sources, the company made an all-solid-state battery prototype with an energy density of 200 watt-hours per liter. It is slated for mass production in 2026.

All-solid-state batteries are rechargeable batteries with solid electrolytes filling the gap between the anode and cathode electrodes. They are expected to be safer than lithium-ion batteries that use flammable liquid electrolytes.

“Our client company is carrying out a series of performance tests on the battery prototype,” said an official from Samsung Electro-Mechanics who declined to disclose detailed information citing confidentiality.

Samsung Electronics is likely to be one of the customers, along with Apple, Google and Xiaomi, which produce smartwatches, Augmented Reality (AR) and Virtual Reality (VR) headsets and other devices, sources said.

The company stressed that its battery is easily stretchable and highly flexible and can come in a wide range of shapes and sizes -- desirable features for wearable devices.

Conventional lithium-ion batteries have shown limitations in flexibility because they might deform when made in a curved or bent shape. The batteries also require extra space for volume expansion during the charging process. So it is challenging to make them small enough to be installed in the miniaturized equipment.

Samsung Electro-Mechanics’ record milestone in one of the next-generation battery technologies comes after CEO Chang Duck-hyun’s aggressive growth strategy.

During the Consumer Electronics Show held in Las Vegas in January, Chang laid out five promising business sectors: glass substrate, silicon capacitor, hybrid lenses for automotive cameras, all-solid-state batteries for small devices and solid oxide electrolysis cells used in manufacturing plants.

In the last three years, the company has applied for some 40 patents overseas on the chemical composition and structure of its all-solid-state batteries. It recently acquired a patent in South Korea on enhanced moisture resistance in oxide electrolytes.

Experts say Samsung Electro-Mechanics’ latest accomplishment could mean a positive signal for electric vehicle battery makers scrambling to roll out the dream battery.

“All-solid-state batteries for EVs have to be bigger in size than those in wearable devices, which leads to a high level of interface resistance and low battery capacity,” said Yang Min-ho, an energy engineering professor at Dankuk University. “But the latest news offers a rosy outlook for the development of EV batteries in the coming years.”