High-Energy (HE) batteries are produced with thick electrodes to store a large amount of active material, which consequently increases the energy content and the driving range. In contrast, High-Power (HP) cells use thin electrodes to reduce the internal resistance thereby improving the power capability and acceleration.
It is well known that the battery can provide high ε but not achieve high P; however, the SCs has an exact opposite situation, i.e., it has basic features of high P but low ε, as shown in Fig. 14 a and c), which are mainly caused by different charge storage mechanisms of battery and SCs.
New applications such as hybrid electric vehicles and power backup require rechargeable batteries that combine high energy density with high charge and discharge rate capability.
Therefore, high rate performance (high P) is a necessary condition for alkali metal ion batteries to achieve fast-charging. As mentioned above, capacitive behavior is not limited by semi-infinite diffusion during charge storage process and is the perfect solution for high-rate targets.
Lithium-ion (Li-ion) batteries are mostly designed to deliver either high energy or high power depending on the type of application, e.g. Electric Vehicles (EVs) or Hybrid EVs (HEVs), respectively.
Differently, battery system reminiscent of high ε because it has a constant potential plateau during discharging, and providing energy of EB= qU (black line at Fig. 15 a), whereas, the slow kinetics progress of alkali metal ions in electrode materials makes it difficult to achieve high P .