With the diversification of global development, our lives are constantly changing, including the various electronic products we come into contact with. You may not know some of the components of these products, such as high-voltage lithium-ion batteries.
What is a high-voltage lithium-ion battery?
High-voltage batteries are batteries with a higher voltage compared to ordinary batteries. They can be divided into two types based on the battery cell and battery pack. High-voltage batteries are defined by the voltage of the battery cell, primarily referring to lithium batteries. Currently, lithium battery cells are mainly classified as high-voltage lithium battery cells and low-voltage lithium battery cells.
Currently, lithium cobalt oxide has been widely studied and applied as a high-voltage anode material. Its non-nafeo2 structure is more suitable for lithium-ion insertion and ejection. Lithium cobalt oxide has a theoretical energy density of 274 mAh/g, a simple production process, stable electrochemical performance, and a high market share.
Development of high-voltage lithium-ion batteries
As the capacity requirements of electrical devices continue to increase, expectations for improving the energy density of lithium-ion batteries are rising. This is especially true for portable devices such as smartphones, tablets, and laptops, which demand smaller size and longer standby time from lithium-ion batteries. Similarly, other electrical devices, such as energy storage devices, power tools, and electric vehicles, are constantly developing lithium-ion batteries that are lighter, smaller, and have higher output voltage and power density. Therefore, developing high-energy-density lithium-ion batteries is a crucial research and development direction for the lithium battery industry.
Application of high-voltage lithium-ion battery technology
In practical applications, only a portion of lithium ions can be reversibly inserted and ejected, resulting in an actual energy density of approximately 167 mAh/g (operating voltage 4.35 V). Increasing the operating voltage can significantly improve the energy density. For example, increasing the operating voltage from 4.2 V to 4.35 V can increase the energy density by about 16%.
High-voltage lithium battery cells have higher energy density and lower safety performance than low-voltage cells, but they have a higher discharge platform. For the same capacity, high-voltage batteries are lighter in size and weight than low-voltage batteries.
High-voltage lithium-ion batteries experience a decrease in certain safety features during use as the voltage increases, thus limiting their widespread adoption in electric vehicles. Currently, the cathode materials used in electric vehicle batteries are primarily ternary lithium batteries and lithium iron phosphate batteries. To improve energy density and meet demand, high-nickel cathode materials such as 811NCM and NCA, high-capacity silicon-carbon anodes, or methods to increase battery space utilization are generally employed to enhance energy density and driving range.
High current and high voltage drive the use of lithium cobalt oxide materials in high-energy-density batteries. For example, the increasingly demanding battery performance requirements of high-end mobile phone battery manufacturers are primarily reflected in the need for higher energy densities. For instance, the energy density required for the cathode in a 4.35V battery is approximately 660 Wh/L, while a 4.4V battery has reached approximately 740 Wh/L. This necessitates anode materials with high compaction density, high void volume, and good structural stability under high and low voltage conditions. However, lithium cobalt oxide electrode materials suffer from drawbacks such as scarce and expensive cobalt resources and the toxicity of cobalt ions, limiting their widespread application in power lithium batteries.
In terms of discharge rate, high-voltage lithium batteries have a higher discharge rate and stronger power than low-voltage lithium batteries. Therefore, high-voltage battery cells are theoretically more suitable for use in products and equipment that require high-rate discharge to better leverage their advantages.
During the research and design process, there will inevitably be various problems. This requires our researchers to continuously summarize their experiences during the design process in order to promote the continuous innovation of products.
