Calendar fade

Li-ion cells used for consumer electronics are designed for 500 100% DOD cycles with 80% retained capacity. In 1998, the company Quallion was founded to develop a Li-ion chemistry with long life, low calendar fade and Zero-Volt characteristics for medical device implants. Since traditional Li-ion chemistries experience a shortened life when the cells voltage are below 1.5-2 V, a Zero-Volt Li-ion cell is especially enabling to pain management devices, where a patient may not routinely recharge the device. 

Usually, the aging of the battery performance has two origins (1) the cycle fade and (2) the calendar fade that is the elapsed time before the battery is not usable at all. An increase in the temperature whether the battery is in active use or not and an increase of the SOC severely affect the degree of degradation. The net result is an increase of the internal resistance and capacity loss L(f), which can be expressed by an empirical law as [25] ... 

DIAGNOSTIC EVALUATION OF POWER FADE PHENOMENA AND CALENDAR LIFE REDUCTION IN HIGH-POWER LITHIUM-ION BATTERIES... 

Uses fading and calendar effects on energy and internal impedance vs. time, temperature, end of charge voltage, etc... 

Aging is a major concern for LlBs, espedaUy for their potential near term adoption into the hybrid dectric and electric vehides (HEV/EV) sector. The demanding targets set by the United States Council for Automotive Research (USCAR) on LIB calendar hfe and cyde hfe (e.g., 15 years for 42 V battery systems and HEVs, 10 years for EVs, and 1000 cycles at 80% depth of discharge over lifetime) warrant detailed understanding of the complex, multimodal aging mechanisms, which lead to capadty decay, cell impedance rise, and power fade. 

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