Ive seen “high rate cells” based on traditional materials. How are the new high rate technologies different?
Designing a cell that can accommodate high discharge and charge rates is an effort to reduce the path length and resistance for the transport of ions and electrons. The resistance of the cells must be lowered by using thin materials, increasing the amount of current collectors and increasing the electrolyte concentration and reducing its viscosity with solvents. Traditional Li-ion cells are based on a LiCoO2 cathode compound. In this material, Li-ions can only be inserted through two dimensional paths, so the rate capability is fundamentally limited. However, rate capability for short pulses can be improved by making the aforementioned changes, and cells for high current pulses have been available for some time. The rate capability of cells based on traditional materials is only about 5C, whereas the cells based on new materials can support rates of more than 30C.
