Manufacturing & Gigafactories Developed 2024 · C12 4 min

What Is Missing for the Adoption of Thin-Film Solid-State Batteries in Smartwatches

Thin-film solid-state batteries are among the most promising candidates for powering the next generation of wearables. They are ultra-thin, lightweight, flexible, and safe, which suits the compact and intricate designs of smartwatches well. Yet they have not displaced conventional cells in the market. This case follows a European microbattery maker weighing entry into the smartwatch sector and asks what still stands between the technology and mass adoption.

Choosing the Market and the Technology

The smartwatch market is attractive for a simple reason: it is already worth billions and is still growing quickly, which makes it a sensible place for a microbattery producer to expand. To pick a chemistry, the company evaluated several advanced options, including solid-state, lithium-sulphur, lithium-metal, flexible, and thin-film designs, scoring each across four equally weighted pillars: technology performance, market entry, cost structure and scalability, and risk. Solid-state and thin-film batteries scored highest. Thin-film lithium-ion batteries, or TFLIBs, can be built from a range of chemistries, from lithium cobalt oxide and LiPON solid electrolytes to iron phosphate and titanate variants, and even non-lithium options such as zinc and vanadium oxide for niche uses. The combination of high energy density, safety, and form factor is what makes them a fit for wearables.

The Manufacturing Reality

The distinctive feature of thin-film solid-state cells is how they are made. Rather than the wet slurry coating used for conventional lithium-ion cells, they rely on dry vacuum processes such as physical and chemical vapour deposition and atomic layer deposition. There is an unexpected advantage here: these are standard techniques in the semiconductor industry, so off-the-shelf equipment exists, which makes the capital burden lower than a wholly new production type might imply. The difficulty lies in tuning those processes to deposit uniform layers reliably and then scaling them. On the operating side, material costs dominate, but energy costs are significant too, driven by plasma sputtering in PVD and the vacuum pumps needed to hold the system under vacuum continuously.

Advantages Against Persistent Challenges

The upsides are clear. A thin profile, long cycle life, fast charging, low self-discharge, and solid electrolytes that reduce leakage and combustion risk all suit miniaturised, flexible devices, and open adjacent uses in medical implants, IoT sensors, and smart textiles. Some designs use more sustainable materials and can be integrated directly into a device, removing the need for a separate pack. The challenges are equally real. Deposition techniques like sputtering and pulsed laser deposition demand high precision, ensuring uniform thickness is hard, and complex processing keeps unit costs high. Scaling to mass-market volumes is unproven, some chemistries degrade over time, fragile materials struggle in rugged conditions, and energy storage capacity can be lower than high-power applications require.

What It Means for the Industry

For a new entrant, the gap between promise and adoption is chiefly about scale-up and cost, not fundamental viability. The regulatory environment is favourable and competition is thin, which gives an early mover room to establish itself. A realistic path runs through functional prototypes in roughly 12 to 18 months and a move toward larger-scale production in a further 18 to 24 months, with early collaborations with premium smartwatch makers to build credibility. Differentiation through sustainability, battery passports, and circular-economy principles strengthens the position, as does considering adjacent applications beyond watches to spread risk and capture more of the technology's potential.

Key Takeaways

Thin-film solid-state batteries suit smartwatches because they combine high energy density, safety, and a thin, flexible form factor.

The company scored chemistries across four equally weighted pillars: technology, market entry, cost and scalability, and risk, with solid-state and thin-film ranking highest.

These cells are made with dry vacuum processes such as physical and chemical vapour deposition, which borrow off-the-shelf equipment from the semiconductor industry.

Lower-than-expected capex is offset by the difficulty of achieving uniform layers and scaling production reliably.

Operating costs are driven by materials plus significant energy use from plasma sputtering and continuous vacuum pumping.

Favourable regulation and limited competition create a clear early-mover opportunity.

A workable timeline runs to prototypes in 12 to 18 months and larger production in a further 18 to 24 months, aided by partnerships with premium brands.