用于能量收集应用的蓄电池解决方案

　　用于能源收集应用的蓄电池解决方案

　　环境光，热梯度，振动/运动，或电磁辐射可以收获电力电子设备。同时，所有能源收集系统需要能量储存的时候，能量无法得到（例如，在夜间为太阳能供电系统）。可充电电池被称为“次级电池”，以区别于“主电池”或“单使用电池”，通常是为这项任务指定的。本文将研究能量收集系统设计人员可用的各种次级电池技术，寻找性价比高、功能强大的电池解决方案。

　　一次电池和二次电池包含一个阴极的基本结构，一个阳极，一个在终端之间移动电荷的电解质，以及一个分离它们的方法。二次电池的特点是采用可充电化学，如镍镉或锂聚合物，或固态薄膜。

　　虽然能量收集系统设计者可能不关注电池结构和化学，但它将有助于开发各种技术的工作知识，因为它是决定所有电池性能指标和限制的细胞化学。（更多的细节和解释蓄电池性能指标参考能量收集区的文章，了解蓄电池规格为能量收集。）

　　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）.