用于能源收集應用的蓄電池解決方案

　　環境光，熱梯度，振動/運動，或電磁輻射可以收獲電力電子設備。同時，所有能源收集系統需要能量儲存的時候，能量無法得到（例如，在夜間為太陽能供電系統）。可充電電池被稱為“次級電池”，以區別于“主電池”或“單使用電池”，通常是為這項任務指定的。本文將研究能量收集系統設計人員可用的各種次級電池技術，尋找性價比高、功能強大的電池解決方案。

　　一次電池和二次電池包含一個陰極的基本結構，一個陽極，一個在終端之間移動電荷的電解質，以及一個分離它們的方法。二次電池的特點是采用可充電化學，如鎳鎘或鋰聚合物，或固態薄膜。

　　雖然能量收集系統設計者可能不關注電池結構和化學，但它將有助于開發各種技術的工作知識，因為它是決定所有電池性能指標和限制的細胞化學。（更多的細節和解釋蓄電池性能指標參考能量收集區的文章，了解蓄電池規格為能量收集。）

　　NiCd and NiMH

　　Nickel-cadmium （NiCd） batteries have enjoyed the longest market run among secondary cells for portable electronics， resulting in a mature technology with low cost. NiCd， however， offers performance advantages as well.

　　For example， the latest NiCd batteries have very low internal resistance， rivaling that of standard alkaline batteries. Next to capacity， internal resistance is the second most important specification as it determines much of the battery’s maximum performance in both charge and discharge， since it decreases battery efficiency. Internal resistance limits operating conditions such as temperature and determines the useful life of the battery. Its low internal resistance makes NiCd a good candidate where high power is required for short periods. High discharge currents of up to 50 times the battery capacity （or 50 A for a 1-Ah cell） are easily tolerated and have a minimal effect on capacity. Terminal voltage changes very slowly as the cell is discharged and NiCd cells do not deteriorate after long periods spent fully discharged. Self-discharge rates are approximately 20 percent per month at 21°C. A common NiCd cell size is AA. The Sanyo Cadnica SY115-ND （Figure 1） provides 70 mAh capacity at 140 mA （0.2 C rate）。 Internal impedance at 50 percent discharge is 16 mΩ （at 1，000 Hz） and charging current can range from 70 mA （standard， 14 to 18 hours charging time） to 1，050 mA （fast， about 1 hour charging time）.