Battery Degradation and Ageing

Abstract

Batteries are subject to degradation in storage due to a variety of chemical mechanisms, such as limited thermal stability of materials in storage, e.g. silver oxide in silver - zinc batteries, or corrosion of metal electrodes, e.g. lead in lead - acid batteries or lithium in lithium / thionyl chloride batteries. Battery performance can degrade during use, due to parasitic reactions, such as lithium metal / battery electrolyte reactions in hthium metal rechargeable batteries. Rates of degradation can be related to a number of factors, such as storage temperature or temperature variations. Battery standards require testing after various storage temperature regimes to detect this.

The effect of degradation of performance can be estimated by real time storage measurements or by accelerated ageing at high temperatures. Other methods for estimation of degradation rates include thermal measurements (microcalorimetry). Causes of increased rates of battery degradation include inaccurate control of charging voltages, e.g. overcharging of lead - acid batteries will cause overheating and excessive loss of electrolyte through gassing. Maintenance of batteries is necessary to ensure good performance, e.g. complete discharge of nickel - cadmium batteries to avoid capacity loss due to the ‘memory effect’ or routine charging of lead - acid batteries to avoid capacity loss in storage due to sulphation (formation of unreactive lead sulphate in the battery plates).

Batteries can be designed to avoid degradation in storage by use of reserve designs in which one component, usually the electrolyte, is omitted in manufacture and is then added just before use, e.g. in sea -water batteries, the magnesium anode would rapidly corrode so batteries are stored dry (without electrolyte) and the battery is activated by immersion in sea water.

Keywords

These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.