1.5v Dry Battery.The influence of temperature on discharge performance

　　The impact of temperature on discharge performance is directly reflected in discharge capacity and discharge voltage. As the temperature decreases, the internal resistance of the battery increases, the electrochemical reaction rate slows down, the polarization internal resistance rapidly increases, the discharge capacity and discharge platform of the battery decrease, affecting the power and energy output of the battery.

　　Taking the discharge of an 80A · h nickel hydrogen battery as an example, the electric vehicle battery is fully charged at room temperature and discharged at 1C current at different temperatures. The relationship between capacity and temperature is shown in Figure 5-1. At a temperature of 20 ℃, the discharge capacity is relatively low. At 20 ℃, the discharge capacity is maximum, and as the temperature increases, the discharge capacity decreases. However, the discharge capacity at medium and high temperatures is significantly larger than that at low temperatures, indicating that the discharge performance at medium and high temperatures is stronger than that at low temperatures. This is because the high temperature is conducive to the diffusion of hydrogen atoms in the alloy, improving the dynamic performance of the alloy. At the same time, the conductivity of the electrolyte KOH increases with the increase of temperature. At high temperatures, the electrolyte has high conductivity, strong current migration ability, reduced migration resistance, and enhanced current charge discharge performance.

　　The influence of temperature on overpotential is more significant. The higher the temperature, the smaller the overpotential, and the easier the electrode reaction is. This is because the overpotential of electrode discharge reaction is determined by two factors: ① the charge transfer resistance on the contact surface between the alloy and the electrolyte; ② The diffusion resistance of hydrogen atoms from the alloy body to the surface. The increase in temperature accelerates the diffusion and charge transfer of hydrogen atoms, promotes electrode reactions, reduces reaction overpotential, and thus increases the discharge capacity of the battery. Similarly, under high temperature conditions, the discharge power capacity of the battery will also increase. At low temperatures (-20 ℃), the discharge performance of batteries is inferior to that at room temperature, mainly due to the excessive stability of metal hydrides at low temperatures and increased electrochemical reaction impedance. At the same time, under low temperature conditions, the Ohmic internal resistance of the battery also increases, affecting the output of the battery's discharge power.

　　For lithium-ion batteries, the discharge capacity drops sharply under the same low temperature conditions, but at high temperatures, the discharge capacity is not lower than at room temperature, and sometimes slightly higher than at room temperature. This is mainly due to the accelerated migration rate of lithium ions at high temperatures. Unlike nickel electrodes and hydrogen storage electrodes, lithium electrodes do not decompose or form hydrogen gas at high temperatures, causing a decrease in capacity. When the battery module is discharged at low temperature, as the discharge proceeds, heat is generated due to resistance and other reasons, causing the battery temperature to rise, resulting in an increase in voltage

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