To date, lithium-ion batteries have proven to be the best solution to the complex electric vehicle (EV) energy storage conundrum. They have a good balance of energy density, power, cyclability, and cost.
However, they are not perfect, with researchers continually coming up with innovative methods to improve performance and safety and reduce costs.
Thus it is now possible to build an EV with a 90 kWh battery pack that does 300-miles on a single charge. However, creating fast charging, energy- and power-dense batteries (more than 300 Wh kg−1 or higher than 4 mAh cm−2) remains challenging.
Even though Li-ion batteries have the highest energy density of rechargeable batteries available, they typically suffer from low power because of reversible Coulombic reactions occurring at both electrodes, involving charge transfer and ion diffusion in bulk electrode materials. Since both diffusion and charge transfer are slow processes, power delivery as well as the recharge time of Li-ion batteries is kinetically limited.
Thus StoreDot’s creative invention describes efficient and economical methods and mechanisms for configuring and prelithiating fast-charging lithium-ion cells, thereby delivering fast-charging lithium-ion cells which are both energy and power dense.
The invention outlines several structural and chemical modifications that allow numerous permutations of features that achieve both energy and power density in fast-charging cells that also have a long cycling lifetime.
These cells have anodes with high metaloid concentrations, such asSi, Ge, and/or Sn, within the anode material, and are paired with cathodes providing a relatively low C/A (cathode to anode load) ratio. The anodes are prelithiated, with an algorithm determining the optimal amount required.
These algorithms also regulate the lithium content achieved through prelithiation by optimizing the electrolyte to increase cycling lifetime, while adjusting energy density with respect to other cell parameters. The method described in the patent also allows for the reduction of the C/A ratio to achieve the required cycling lifetime.
As the EV fleet continues to rapidly grow, so too do drivers’ expectations. This StoreDot patent provides researchers and electric vehicle battery cell manufacturers with methods and processes to develop and produce better fast-charging lithium-ion EV batteries that are both energy and power dense while offering longer cycle life.