钠电池过放的防护措施有哪些？

What protective measures prevent over-discharging sodium-ion batteries?

钠电池过放采用软件监控、硬件闭锁、使用规范、材料优化四维防护，实时管控放电下限电压，杜绝负极完全脱钠造成不可逆损伤。软件 BMS 核心防护：每串独立电压采样通道，单体放电至 2.6V 提前预警，降至 2.5V 标准截止电压瞬间断开放电回路，负载立即断电；配备静态亏电监测，电池静置状态持续监控单串电压，电压下滑至 2.55V 自动启动微量均衡补电，防止静置缓慢过放；设置放电时长保护，负载持续耗电超额定时长强制切断，杜绝设备空载持续亏电；后台记录每一次低电压放电事件，批量电芯出现过放记录提前均衡检修。硬件回路防护：放电主回路串联低压保护 MOS 管与一次性保护保险丝，双重硬件闭锁，即便 BMS 程序故障，电压跌破阈值物理断开输出；PACK 低压报警指示灯，电压接近下限提前提醒用户停机；储能变流器、电动车控制器写入 2.5V 单体低压保护逻辑，负载侧同步限制深度放电。电芯材料优化防护：负极硬碳增加预留储钠位点，少量钠离子即便深度放电仍留存，维持 SEI 膜基础稳定；电解液添加负极钝化保护添加剂，低电位下快速形成临时防护层，减轻 SEI 膜破损程度；正极选用低金属溶出改性材料，过放工况下过渡金属析出量大幅降低，减少负极二次腐蚀损伤。日常运维规范防护：设备闲置前统一充至 50%-70% 半电状态存放，禁止满亏电长期静置；户外备用电源、基站电池每 3 个月补电一次，避免缓慢自放电导致过放；负载设备设置低电量提醒，用户及时关机充电；定期做整包压差均衡，消除单串提前放空的一致性缺陷。四维防护互相兜底，软件失效时硬件自动切断放电，最大程度避免深度过放损伤电芯，延长电池整体使用寿命。

Four-dimensional protection including software monitoring, hardware lockout, operation rules and material optimization controls discharge cut-off voltage and eliminates irreversible anode damage from full sodium extraction. Core BMS software protection: independent per-string voltage sampling triggers warning at 2.6V and cuts discharge circuits instantly at the 2.5V limit. Static depletion monitoring recharges cells slightly once resting voltage hits 2.55V to prevent slow over-discharge from self-discharge. Discharge time limit forces power cut after excessive load consumption, with historical low-voltage logs for batch maintenance. Hardware circuit protection: dual low-voltage MOS and one-time fuse lock the discharge main loop to physically cut output under threshold voltage even with BMS failure. Low-voltage indicator reminds users to shut down early; PCS and vehicle controllers embed 2.5V cell protection to restrict deep discharge on the load side. Material optimization: hard carbon anodes reserve partial sodium storage sites to retain minimal sodium and stabilize SEI under deep discharge. Anode passivation additives form temporary protective layers at low potentials to mitigate film rupture. Modified low-metal-dissolution cathodes reduce transition metal precipitation during over-discharge and secondary anode corrosion. Daily maintenance rules: charge devices to 50%-70% before long-term storage, avoid fully depleted placement. Outdoor backup and base station cells receive supplementary power every 3 months to prevent over-discharge from self-consumption. Low-battery reminders prompt timely recharge; regular pack equalization eliminates inconsistent cells that deplete early. Four layers of protection back each other up with automatic hardware cut-off upon software failure to minimize deep over-discharge damage and extend overall cell service life.