News

Sep 07, 2023

Battery Materials

Electric vehicle consumers desire increased range and fast charging to get back

Electric vehicle consumers desire increased range and fast charging to get back on the road quickly. Storing more energy relative to weight and volume and accepting higher charge rates increase the requirements for material performance, stability, and safety. Wider EV adoption demands improved material utilization along the supply chain.

META is developing new battery materials and manufacturing techniques to address all these challenges. NCORE™ polymer composite current collectors, made with proprietary PLASMAfusion® high-speed vacuum coating technology, significantly reduce weight, while adding a fuse-like safety feature. NPORE® ceramic separators feature <1% heat shrinkage for increased safety and offer superior electrochemical performance.

Current collectors are essential components of lithium-ion batteries, consisting of aluminum (Al) and copper (Cu) foils for the cathode and anode, respectively. Collectively, current collectors account for about 15% of the total battery cell mass and do not actively contribute to battery capacity. Al has a low density of 2.70 g/cm3 while Cu is much heavier at 8.96 g/cm3 such that Cu foil current collectors account for more than 10% of the weight of a typical Li-ion battery.

A PET/PEN plastic substrate, coated with thin layers (150-250nm) of Cu on each side and embedded metal bridges for through conductivity, promises the same functionality and cost as copper foil, while providing several benefits. Weight is reduced by ~85% and reduced thickness allows more active material, increasing energy and power density. In case of thermal runaway, the plastic melts, improving safety by retarding battery self-ignition. Lower copper content reduces the energy input to produce the battery and enhances recycling.

NPORE® is the world's first flexible, freestanding ceramic nanoporous membrane separator for lithium ion batteries. NPORE® separators eliminate the use of plastic substrate, provide superior functionality and outstanding heat resistance for current and next generation lithium ion batteries.

NPORE® features include:

The separator and the current collectors (CCs) constitute some of the fundamental components of every lithium-ion battery (LIB). While not directly participating in the kinetics of the electrochemistry, these passive components are a principal determinant of the safety, performance, longevity, weight, and volume of a cell. Decreasing their weight or volume within the range where their functionalities are not negatively affected can directly improve the gravimetric or volumetric energy and power density of a cell. In the presentation below, we present a new approach to enhancing the safety and performance of LIBs of various sizes and chemistries that utilizes two next-generation, smart passive components, namely, a metal–polymer composite CC (NCORE™) and a nanoporous ceramic separator (NPORE®). NCORE™ is fabricated by coating a 6-μm-thick polymer substrate with a thin (250 nm) layer of copper (Cu) metal on each side. High-density Cu elements (bridges) are also embedded within the substrate in this metallization process. The resulting material exhibits increased conductivity in both in-plane and out-of-plane directions. Functioning as a smart fuse, NCORE™ prevents additional inrush current from triggering a thermal runaway that can potentially lead to a dangerous fire that is extremely difficult to extinguish in a cell when its internal temperature exceeds 250°C. Eliminating up to 90% of the Cu contained in a typical CC, NCORE™ reduces the weight of the battery and improves its performance and recyclability. NPORE® is a proprietary, robust, nanoporous ceramic separator that is highly resistant to melting and shrinking. In the case of an internal short circuit between the electrodes, which may be caused by a dendrite or other defect, NPORE® does not shrink away from the location of the defect, inhibiting the heat caused by the short circuit from propagating a thermal runaway. The combination of NCORE™ and NPORE® offers an innovative safety solution for LIBs of a wide range of chemistries and form factors.