## 3 Results and Discussion  
Based on the battery lab tests and simulated parameters, the internal resistance level of the LSB pack was around 10 times higher than that of the LIB. The internal resistance has a great influence on LSB applications in an electric vehicle. In an electric vehicle operation, the electric load of the battery pack contains the electric power-train system and other electric auxiliaries such as DCDC, air compressors, etc. The battery output voltage is the actual voltage, \(u_{out}\), applied on the electric load. For certain vehicle drive cycles, the electric load usage was determined; however, the \(u_{out}\) applied on the electric load is affected by the difference in internal resistance. Equation (2) can be used to explain the internal-resistance-effect mechanism, in which the deviation of \(u_{out}\) from \(u_{occ}\) is directly related to the internal resistance, \(r_{0}\), and a large internal resistance will increase the voltage variance between \(u_{occ}\) and \(u_{out}\), resulting in an unstable output voltage on the vehicle's electric load, which would shorten the service life of the auxiliaries. Considering the efficiency from the electric vehicle system level, the power and energy usage on the electric load (power-train and auxiliaries) is battery-effective work. The effective work power, \(P_{out}\), and the effective energy, \(E_{out}\), can be determined by Equations (16) and (17), respectively:  
\[P_{out}=u_{out}\cdot I \tag{16}\]  
\[E_{out}=\int P_{out}. \tag{17}\]  
Meanwhile, the internal-resistance-generated heat is useless work for the electric vehicle, and the battery power loss, \(P_{loss}\), and useless heat energy, \(E_{loss}\), are expressed in Equations (18) and (19), respectively:  
\[P_{loss}=I^{2}\cdot r_{0} \tag{18}\]  
\[E_{loss}=\int P_{loss}. \tag{19}\]  
For certain drive conditions, \(P_{out}\) is determined by the power demand of the vehicle, which is affected directly by the battery internal resistance. It has been found that a larger internal resistance causes larger battery power loss and battery energy loss. Simulationswere conducted to analyze the operation performance of the LSB and the LIB in an electric vehicle application for three typical driving conditions. In all driving cycles, namely the NEDC, WLTC and HWFT, the gradient was 0. The NEDC was chosen as the first simulation condition. As shown in Supplementary Figure S8a [28; 29], the entire driving cycle (total time, 1180 s) included urban driving cycles (UDCs) and extra-urban driving cycles (EUDCs). The first 780 s was the UDC (maximum speed 50 km/h), and the next 400 s was the EUDC (maximum speed 120 km/h). This driving cycle has been widely used to test vehicle energy consumption, emissions, and driving range [30; 31; 32]. Figure 4a,b exhibits the voltage variation curve under the NEDC for the LSB and the LIB, respectively, indicating that the charge and discharge voltage output of an EV battery increases and decreases, respectively, due to internal resistance. A large battery internal resistance causes a sharp voltage vibration. Since the LSB has a larger internal resistance, it experienced a more severe voltage vibration (from 359.9 to 441.5 V) in comparison to the LIB (344.9-357.5 V). It can be concluded that the high LSB internal resistance, and resulting unstable output voltage, is one of the main obstacles for the LSB's electric vehicle application. During the driving-cycle simulation, the battery power and energy to overcome all the mechanical drag force were defined as driving power/energy, while the internal-resistance-resulting power and energy loss was ascribed to battery power/energy loss. In reality, the usage of battery power and energy contains driving power/energy and power/energy loss. Hence the gap between the driving power and the battery power at certain time points is the battery power loss, and a cumulative energy loss indicated by the gap between driving energy consumption and battery energy consumption can vivid indicate the battery performance in EV applications.