UC San Diego

Compact, rechargeable batteries in the capacity range of 1-100 mAh are targeted for form-factor-constrained wearables and other high-performance electronic devices, which have core requirements including high volumetric energy density (VED), fast charging, safety, surface-mount technology (SMT) compatibility, and long cycle life. To maximize the VED, anodeless solid-state lithium thin-film batteries (TFBs) fabricated by using a roll-to-roll process on an ultrathin stainless-steel substrate (10-75 μm in thickness) have been developed. A high-device-density dry-process patterning flow defines customizable battery device dimensions while generating negligible waste. The entire fabrication operation is performed in a conventional, humidity-controlled cleanroom, eliminating the need for a costly dry-room environment and allowing for simplified, lower-cost manufacturing. Such scale-up using an anodeless architecture also enables a thermal-budget-compatible packaging and metallization scheme targeted at industry-compatible SMT processes. Further manufacturability improvements, such as the use of high-speed tests, add to the overall range of elements necessary for mass production.