IPS’ first battery encapsulation patent, U.S. Pat No. 6,916,579 granted in 2005, was for the initial invention of a metal foil encapsulation for thin-film batteries. This second patent expands on the first, in part, by including a vertical conducting element that eliminates the need for peripheral current collectors as invented by Oak Ridge National Labs in the 1990s. Such peripheral current collectors are commonly used in other thin-film batteries and necessitate a larger footprint. IPS’ patented conductive feature in the vertical direction, combined with the metal film encapsulation as a current collector and terminal, maximizes the active area efficiency. This means more power and higher capacity per unit area than other TFBs. In addition, the metal film encapsulation is peripherally bonded to the cell’s metal foil substrate to form a tiny metal cage around the cell and, therefore, a hermetic seal. The dual purpose substrate layer (both substrate and bottom half of the cell encapsulation) reduces cost and materials, simplifies the design and minimizes cell thickness.
Conventional prismatic lithium ion batteries use a pouch style package where the cell substrate is in addition to the top and bottom metallized polymer foils forming the pouch (adding thickness), and the current collectors are peripheral to the cell (adding area). Other TFB encapsulations, such as polymeric and ceramic materials have been used by some developers but lack a sufficient moisture and oxygen barrier, a characteristic which is vital for a battery containing a metallic lithium anode. Such non-metallic encapsulations allow high moisture vapor and oxygen transmission rates resulting in cell degradation within months, even in low humidity environments. In contrast, the IPS metal film encapsulation provides cell protection for more than a decade.
Shawn Snyder, Director of Engineering at IPS and co-inventor of the metal film encapsulation technology commented, “Our advanced metal film encapsulation method has evolved to provide a very thin, flexible barrier to physically protect the cell and minimize moisture and oxygen ingress while increasing the reliability and longevity of our solid-state batteries. The exceptional encapsulation performance we have achieved contributes to our technology leadership and market success for lithium-based solid-state thin-film batteries.”
In addition to this U.S. patent grant, IPS anticipates the patent will soon be granted in Europe, Japan, Korea, China, and Taiwan where it is presently in the final stages of examination. Besides other patents and substantial trade secrets, IPS currently employs this metal film encapsulation to fabricate its award-winning THINERGY Micro-Energy Cell (MEC) products, a family of 4V, all-solid-state, rechargeable, thin-film batteries. In addition to providing an unprecedented 100,000 recharge cycles, MECs deliver more power and higher energy density than any other rechargeable battery product of similar size. MECs are paper-thin (170µm), flexible and intrinsically safe. They can be used as backup power for memory modules, solid-state drives and real-time clocks, or to power small electronic systems and wireless sensors, including Bluetooth Smart devices.