Manufacturing Scale-Up of Anodeless Solid State Lithium Thin Film Battery for High Volumetric Energy Density Applications

Compact, rechargeable batteries in the capacity range of 1-100 mAh are targeted at 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. Solid-state lithium thin film batteries (TFB) fabricated on thin substrates and packaged in a multilayer stack offer these attributes, overcoming the limitations of lithium-ion batteries based on liquid electrolytes. To maximize the VED, an anodeless architecture fabricated using a roll-to-roll process on an ultrathin stainless-steel substrate (10-75 um in thickness) has been developed. These microbatteries use a lithium cobalt oxide (LiCoO2) cathode and lithium phosphorus oxynitride (LiPON) electrolyte deposited by thin film techniques to enable key battery performance metrics. 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 that allows 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. A perspective on requirements and opportunities for this technology as it evolves is provided.