How complex is battery aging?

Battery aging is very complex, non-linear and influenced by many parameters. It can be observed for example, that batteries age even if they are not used. But, in general, batteries age faster if they are used. To manage the complexity, it is common practice to split aging into three buckets: calendric, cyclic, and reversible aging:

Why do home battery systems aging?

Most days, home battery systems store more energy than is consumed. As a result, the storage systems are cycled at high SOC ranges of 50 to 100 percent, which causes increased aging. To reduce the aging, system settings should delay charging the batteries until later in the day.

How does cyclic aging affect battery life?

Cyclic aging is dominated by the energy throughput – the amount of energy that moves through the battery in a specific period of time – so the number of cycles plays a key role. However, small cycles are less harmful than big ones, as shown in Figure 4 (below).

Do batteries age faster if they are used?

But, in general, batteries age faster if they are used. To manage the complexity, it is common practice to split aging into three buckets: calendric, cyclic, and reversible aging: Calendric aging – The gradual degradation of batteries over time, even if they are not used.

Why does charging a battery increase aging?

One reason is that charging a battery with high power raises the temperature, which leads to accelerated aging. Another reason is the increased risk of lithium plating. Besides temperature, charging power, throughput, and depth of discharge, other effects such as phase shifts also accelerate battery aging.

What causes aging in lithium ion batteries?

The main cause of aging in lithium-ion batteries is the growth of the Surface Electrolyte Interphase (SEI). The SEI layer forms on the negative electrode during the first charging cycle, commonly referred to as the formation cycle.