What are the factors that affect the life of lithium batteries

3) Charging cut-off voltage; 4) Charging speed; 5) Operating temperature; 2. The effect of charging times on lifespan Many customers and even some engineers believe that the life expectancy indicated on many lithium battery specifications is estimated: the number of charging cycles is about 300 , I thought that as long as you plug in the charger once, it counts as one charge. In this way, if the customer plugs in the charger twice a day, the battery life will be less than half a year. Since many people know that batteries are still used in nickel-metal hydride batteries and nickel-cadmium batteries, because this type of battery has a recall effect, but lithium batteries have no recall effect, the battery university believes that a complete cycle of lithium batteries should be described as follows: lithium The battery is charged to an additional voltage of 4.2V with a current of 1C (maximum charging current), and is trickle charged with a charging current of 0.05C until the battery is full, and then discharged to 3V at a discharge rate of 1C. This process is a complete charge-discharge cycle . It is not a perfect charging and discharging cycle without overflowing. If your battery is fully charged and uses one-tenth of the power, and then overflows, this is a tenth cycle, so charging 10 times, it basically counts as a cycle. The life cycle of a general lithium battery is 300 to 500 times (the battery is not completely damaged at the moment, but the capacity is only 60% to 70% of the initial capacity). 3. The impact of depth of discharge DoD on lifespan Many customers and even some engineers believe that too many recharges of lithium batteries will damage the battery, so during use, they are overflowing. Wait until the battery capacity is close to 0 before recharging and charging. The cut-off voltage is set to the highest threshold voltage of 4.2V. The battery university believes that the lower the depth of discharge of lithium batteries, the better, as shown in Figure 2, for example, a 1AH LiPO4 battery, at 100% DoD, the number of cycles is about 600, and the capacity supplied within the lifetime is Ju003d1AH*600u003d 600AH, if it is deeply discharged with 40% DoD, it can cycle 3000 times, and the capacity supplied within the lifetime is Ju003d1AH*0.4*3000u003d1200AH, which is 50% longer than the 100% depth of discharge. Toyota's dual-engine hybrid vehicle has a battery warranty of 160,000 kilometers for 8 years. The publicity is: shallow charge and shallow discharge, longer life. 4. The influence of charging voltage on lifespan The battery university believes that the charging cut-off voltage has a critical influence on the lifespan of the battery. There are two important criteria for lithium batteries below 4.2V: 1. The charging cut-off voltage is below 4.2V , For every 0.1V drop, the number of rechargeable cycles will double. 2. Every time the overflow voltage drops by 70mV, the usable capacity of the battery will drop by 10%. For electric vehicles, the lithium batteries in satellites still have to have a service life of more than 8 years. To accomplish this, the battery is only charged to 3.90V/cell or lower. An interesting discovery by NASA is that lithium ions residing above 4.10V/cell tend to be analyzed due to the oxidation of the electrolyte on the cathode, while lithium ions charged to a lower voltage lose capacity due to the accumulation of SEI on the anode. The National Aeronautics and Space Administration (NASA) reported that once lithium ion has passed the eight-year mark after passing about 40,000 cycles in the satellite, the deterioration of battery quality caused by this phenomenon will soon develop. Charging to 3.92V/battery seems to be able to extend the service life to the greatest extent, but this can only reduce the capacity by about 60%. Chalmers University of Technology in Sweden reported that the use of a reduced 50% SOC (state-of-charge) charging capacity can increase the life expectancy of car lithium batteries by 44130%. Most designers for mobile phones, laptops, tablets and digital cameras will charge lithium batteries to 4.20V. This is the limit threshold of operation. Since the consumer electronics update cycle is generally 3 years, users want a longer battery life. Many counterfeit brands seek to drain all the capacity and increase the charging voltage to 4.3V or even higher. On the other hand, the industry pays more attention to life span and may choose a lower voltage threshold. The charging threshold is set by each manufacturer, and there is no unified specification. 5. How does the charging speed affect the lifespan of the battery? The university believes that the charging speed (charging current) of a lithium battery has a vital influence on the life of the lithium battery. The faster the charging speed, the shorter the battery life. Figure 5 below is a 900mAH lithium battery as a comparative test, C: the capacity value indicated by the battery. For example, 2600mAh lithium rechargeable battery, 1Cu003d2.6A; 3400mAh lithium rechargeable battery 1Cu003d3.4A. From the test results, it can be seen that at a charging speed of 1C, after 500 cycles, the remaining full capacity is 800mAH, which is reduced by 100mAH, and the capacity is reduced by about 11%. If charging at a charging speed of 2C, after 500 cycles, the remaining full capacity is 500mAH, which is reduced by 400mAH, and the capacity drops by about 44%. At present, mobile phone manufacturers are looking for charging speed, but they sacrifice battery life for value. Fortunately, the frequency of consumer electronics updates is high enough. 6. The effect of temperature on life span? Battery University believes that the operating temperature of lithium batteries has a great impact on battery life. Tests have shown that lithium batteries have undergone 100 cycles of charging and discharging. At 20°C, the capacity of NCM lithium batteries only drops to 97.7. When the temperature rises to 60°C, the battery capacity drops to only about 60%. Therefore, keep the battery at room temperature as much as possible. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous: Can lithium iron phosphate batteries be used for photovoltaic energy storage power generation?