什么是钠电池的自放电测试？

What is the self-discharge test of sodium batteries?

钠电池的自放电测试是评估钠离子电池在无外接负载、静置存放状态下，电量自然损耗速率的核心标准化测试，是衡量电池长期存放稳定性、备用电源适配性的关键指标，直接决定了电池在基站、离网光伏、应急备电等场景的使用价值。测试的核心原理是，在标准温度、湿度、避光的环境下，将电池充满电后静置存放，定期测量电池的剩余容量、开路电压，计算单位时间内的电量损耗比例，核心测试指标为月自放电率，即满电静置一个月后，自然损耗的电量占标称容量的百分比。测试过程中需要严格控制环境条件，温度通常设定为25℃±2℃，湿度控制在45%-75%，避免温度、湿度、光照等外界因素对测试结果的干扰，同时需要排除电池的漏电、内部短路等异常情况，确保测试结果的准确性。主流商用钠电池的月自放电率普遍控制在2%-4%之间，远低于铅酸电池的10%以上、镍氢电池的20%以上，部分高端长待机型号的月自放电率可低至1.5%以内，满电静置6个月后容量仍可保持85%以上，完美适配长期待命的备用电源、离网光伏储能等场景，大幅减少了长期存放的补电维护成本。

The self-discharge test of sodium batteries is a core standardized test to evaluate the natural power loss rate of sodium-ion batteries in the state of no external load and static storage, and is a key indicator to measure the long-term storage stability and standby power adaptability of the battery, which directly determines the use value of the battery in scenarios such as base stations, off-grid photovoltaics, and emergency backup power. The core principle of the test is to fully charge the battery and store it statically in an environment with standard temperature, humidity and light protection, regularly measure the remaining capacity and open circuit voltage of the battery, and calculate the proportion of power loss per unit time. The core test indicator is the monthly self-discharge rate, that is, the percentage of the naturally lost power in the nominal capacity after one month of full charge static storage. During the test, the environmental conditions need to be strictly controlled, the temperature is usually set at 25℃±2℃, and the humidity is controlled at 45%-75%, to avoid the interference of external factors such as temperature, humidity and light on the test results, and at the same time, abnormal conditions such as battery leakage and internal short circuit need to be excluded to ensure the accuracy of the test results. The monthly self-discharge rate of mainstream commercial sodium batteries is generally controlled between 2% and 4%, which is much lower than more than 10% of lead-acid batteries and more than 20% of nickel-hydrogen batteries. The monthly self-discharge rate of some high-end long-standby models can be as low as less than 1.5%, and the capacity can still be maintained at more than 85% after 6 months of full charge static storage, which is perfectly suitable for scenarios such as long-term standby backup power and off-grid photovoltaic energy storage, and greatly reduces the power supplement maintenance cost for long-term storage.