Driven by the growing demand for new energy vehicles, driving range has become a critical factor in consumer decision-making. It also plays a vital role in policy formulation by government agencies. As a result, high-energy-density lithium batteries have gained significant popularity. With increasing technological advancements, these high-power lithium batteries are gradually becoming the industry standard.
However, there remains a challenge: the lifespan of high-energy-density lithium batteries tends to degrade more rapidly than expected, which creates a mismatch with the vehicle's overall mileage and calendar life. This inconsistency poses significant obstacles to the widespread adoption of new energy vehicles.
**Why do high-specific-energy lithium batteries degrade faster?**
From a microscopic perspective, during the operation of a lithium battery, irreversible electrochemical reactions such as electrolyte decomposition, active material deactivation, structural collapse of electrodes, and reduced lithium ion insertion/extraction can occur, leading to capacity loss. Under high voltage and temperature conditions, the highly delithiated positive electrode surface is more prone to react with the electrolyte. For instance, NCM811 exhibits much higher reactivity with the electrolyte compared to NCM111 when fully charged. Thus, the higher the charge/discharge voltage and temperature, the more rapidly the battery’s capacity decreases.
On a macro level, accurate measurement of current, voltage, and temperature, along with effective thermal, power, and energy management, is essential. Additionally, understanding the battery’s life status and extending its service life is crucial. Battery Management Systems (BMS) play a key role in this process.
**Exploring Solutions from Multiple Dimensions**
To address the issue of shorter lifespan in NCM811 compared to energy-grade lithium batteries, the industry is exploring solutions across multiple areas—materials, electrolytes, separators, and BMS.
In terms of materials, modifying the surface of NCM811 particles can enhance performance. The type of electrolyte additive used affects the polarization degree and speed, which in turn influences cycle life and safety. By using an electrolyte that minimizes internal parasitic reactions, the cycle life and safety of high-specific-energy power lithium batteries can be significantly improved.
Penghui Energy has enhanced the stability and safety of high-specific-energy lithium batteries under high-temperature and high-pressure conditions through the use of ceramic and polymer composite coatings. They have also developed a specialized silicon-carbon negative electrode process and electrolyte system, achieving a first-cycle efficiency of over 86%, effectively addressing the rapid capacity decay in the first 50 cycles and improving both capacity and longevity.
At the BMS level, Professor Wei Xuezhe from Tongji University proposed a battery pack optimization design based on the “electric-thermal-life†coupling model. This system can measure cell capacitance, estimate capacity, and collect multi-dimensional data over time. It ensures battery pack consistency and enables multi-factor and multi-physics coupling. According to Professor Wei, this represents the third-generation BMS, which focuses on life estimation, prediction, and management. It includes comprehensive series-parallel schemes, equalization strategies, and thermal management systems, enabling effective control of battery life degradation.
With market demand driving innovation, companies like Thornton New Energy, Guoxuan Hi-Tech, and Penghui Energy are actively developing high-power, energy-dense lithium batteries. Material suppliers like Shanshan are also capitalizing on this trend. These efforts in addressing the lifespan issues of high-energy lithium batteries are not only beneficial for the power battery industry but also support the broader development and adoption of new energy vehicles.
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