钠离子电池和镍氢电池的核心区别是什么？

What are the core differences between sodium-ion batteries and Ni-MH batteries?

从材料、性能、成本、环保、应用五大维度存在根本性区别。一电化学体系：钠电池依靠钠离子迁移，无镍、稀土金属；镍氢依赖稀土储氢合金，稀缺资源制约产能。二低温性能：钠电池 - 20℃保留 85% 容量，镍氢低温容量衰减超 50，北方冬季无法正常使用。三循环寿命：钠 3000 次以上，镍氢仅 500~1200 次，更换频次更高。四自放电：钠月自放电 2%~4%，镍氢月自放电 15% 以上，长期闲置亏电严重。五能量密度：钠重量能量密度约 120~160Wh/kg，镍氢仅 60~90Wh，同等续航电池重量翻倍。六成本：钠原料储量充足，规模化后价格仅镍氢 60%~70%；镍氢稀土涨价波动大。七环保：钠无重金属、稀土污染；镍氢含稀土、镍重金属，回收流程复杂。八适用场景：钠适配储能、低速车、户外电源；镍氢仅少量老式混动汽车、小型数码备用电池，市场持续萎缩。

Fundamental differences cover materials, performance, cost, environmental protection and applications. 1. Electrochemical system: Sodium relies on sodium ion migration without nickel or rare earths; Ni-MH adopts rare earth hydrogen storage alloys constrained by scarce resources. 2. Low-temperature performance: Sodium retains over 85% capacity at -20℃, while Ni-MH fades over 50% and fails in northern winters. 3. Cycle life: Sodium exceeds 3,000 cycles vs merely 500~1200 for Ni-MH with frequent replacement. 4. Self-discharge: Monthly self-discharge of sodium is 2%~4%, above 15% for Ni-MH with severe power loss during long standby. 5. Energy density: Sodium reaches 120~160 Wh/kg vs only 60~90 Wh/kg for Ni-MH, doubling weight at equal range. 6. Cost: Abundant sodium raw materials cut mass price to 60%~70% of Ni-MH; rare earth prices fluctuate sharply for Ni-MH. 7. Environmental protection: Sodium contains no heavy metals or rare earth pollution; Ni-MH includes nickel and rare earths with complicated recycling. 8. Scenarios: Sodium fits energy storage, low-speed vehicles and outdoor power; Ni-MH is limited to old hybrid cars and small digital backups with shrinking market share.