Reviving Aged Lithium‐Ion Batteries and Prolonging their Cycle Life by Sinusoidal Waveform Charging Strategy

Abstract

Traditional high power constant current-constant voltage (CCÀCV) charging leads to the degradation of Li-ion batteries. Thus, aging due to charging is a primary issue to be overcome in application technology. This study proposes the impacts of a sinusoidal waveform charging strategy for charging Li-ion batteries. Specifically, a negative voltage is introduced in the charging process to reverse passivation layer formation. After few cycles of sinusoidal waveform charging, aged cells can be revived. Tests reveal that the available capacity of an aged cell can be improved by a maximum of 18.7 % relative to the original rated power. After 600 charging-discharging cycles of new cells, the cells charged using the sinusoidal waveform strategy possess approximately 15 % more electrical capacity than do cells charged using the conventional CCÀCV method, indicating an increase in battery cycle life. The suppression of interfacial resistance is characterized by electrochemical impedance spectroscopy. Sinusoidal waveform charging can reduce charging time by half and the maximum rise in temperature by 6 8C compared with the CCÀCV charging method.The rapid increase in the use of commercial Li-ion batteries in portable electronic devices and, more recently, electric vehicles and energy storage systems has engendered an urgent demand for considerable battery performance enhancement. Battery degradation is the primary limitation of Li-ion batteries used in the aforementioned applications. A major factor in battery degradation is the continuous passivation of solid electrolyte interphases (SEIs). [1] An SEI consists of solid Li complexes that are created due to the combination of Li ions and decomposed electrolyte with excess electrons attributed to charging. [2] Constant high-power charging was suggested to accelerate aging. [3] Therefore, considerable engineering efforts have been undertaken to stabilize the SEI over time. The development of charging methods would ensure that capacity loss would not be severe in the short term and enable long-term Li-ion battery utilization. Among constant-trickle-current charging, constantcurrent (CC) charging, and CC-constant-voltage (CCÀCV) charging methods, [4] CCÀCV is most extensively used. CCÀCV charging involves charging a battery at a CC until its voltage reaches the predetermined limit, followed by CV charging until the current decreases to a predetermined low value. However, SEI formation can occur near the end of the CC-charging step during normal CCÀCV charging if the charging current rate reaches or exceeds a certain value. [5] Thus, the charging performance of the CCÀCV method cannot sufficiently satisfy the long-cycle-life requirement of the consumer. The development of charging methods that balance battery degradation and fast charging remains a challenge.Reflex charging method applies a very short discharging pulse during pulse charging and resting periods. Because passivation layers in different types of batteries are grown mainly via reduction reaction, the discharging pulse ...

Composite Sinusoidal Waveform Generated by Direct Digital Synthesis for Healthy Charging of Lithium-Ion Batteries

“…The maximum of recovery capacity is about 8%. The result is consistent with that of charge-discharge machine which we have done via commercial charging instrument [12].…”

“…The waveform is shown in Figure 1a. We have already verified and demonstrated that this composite sinusoidal waveform is effective in prolonging the 18650 lithium-ion battery life [12]. The waveform has voltage level of 3.6 V. The upper cycle and lower cycle are 0.7 V and 0.2 V, respectively.…”

“…All the values of a therein can be correlated to a linear function b(x). Taking advantage of the feature that a straight line has a constant slope, the following relation can be expressed as Equation (12) [27,28]:…”

Development of a Hybrid Electric Motorcycle that Accords Energy Efficiency and Controllability via an Inverse Differential Gear and Power Mode Switching Control

“…The performance was then evaluated by two tests: the worldwide motorcycle test cycle and new European driving cycle. The fuel reduction and kinetic efficiency enhancement can be achieved by the electrification of motorcycles; especially, the state-of-the-art charging strategy has overcome the battery aging problems [19,20]. In this study, a hybrid electric motorcycle (HEM) was developed based on a novel parallel power system architecture.…”

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“…Theoretical models of passenger thermal comfort have been studied [15][16][17][18], as well as factor evaluation [19], fluidic design [20,21], simulation analysis [22][23][24], experiment [25,26], and management strategy formulation research [27]. Ever-increasing demands in low-carbon emission vehicles [28][29][30][31][32] have propelled AC development considering energy efficiency. Therefore, we introduce a novel structural design of an air outlet to approach regional AC and air exchange.…”