Batteries are the main limitation to the wide spread adoption of electric vehicles and plug in hybrids.  Battery energy density must be improved to increase EV driving range and lower battery cost.  State of the art high energy lithium batteries use NCA cathode and graphite anode e.g. cylindrical 18650 cells that can provide specific energy up to 250 Wh/kg.  Replacement of graphite with silicon based anode is mandatory to further boost specific energy.  However, cells with silicon based anode have poor cycle life and very high swelling.  Proper selection of cathode is also important to attain high energy density when paired with Silicon based anode.  Although the capacity of Si-based anode materials are high, their intercalation potential is much higher than that of Li or graphite which translates to a lower overall cell voltage (at least 0.4V lower) resulting in lower energy density.  A high capacity and high average voltage cathode is required to compensate the overall drop in the average voltage.

In this work, Cobalt-Rich Composite (CRC) cathode has been developed that also contains significant amount of Nickel and Manganese. The resulting CRC cathode shows stable high voltage performance compared to LCO. Traditionally the structure of LCO cathode degrades at high charge voltages (>4.4V) when >0.5 moles of Li are extracted from the structure. The CRC cathode enables high electrode active content (>97%) and high electrode density (>4.0g/cc), high average voltage (3.95V) and high specific capacity (>190 mAh/g in half cell). Most importantly, CRC cathode does not exhibit any voltage fade upon cycling at higher voltages (>4.45V) as observed in lithium rich manganese rich composite cathode.  

CRC cathode has been complemented with a high capacity SiO_x-based anode electrode in a high energy cell. Typical commercially available Si-based materials suffer from large volume expansion resulting in pulverization and poor cycle life. We present high capacity SiO_x-based anode (>1400 mAh/g) electrodes with high percent active content (>80%) that has shown to cycle over 500 times.  A novel anode fabrication approach has been used taking advantage of a high strength binder, carbon nanotube network and pre-lithiation.  Swelling, cycling and abuse testing results of the cells will be presented. Figure 3 shows 10Ah capacity pouch cells integrating CRC cathode and SiO_x anode with specific energy of ~350Wh/Kg. The cells show excellent rate capability as required for automotive and drone applications. There is significant energy above lower cut off voltage 3.0V required by consumer electronic devices. This presentation will also cover remaining challenges associated with CRC cathode and SiO_x anode with respect to synthesis, performance and cell manufacturing.