With Telsa in the lead, the electric vehicle market is growing around the world. In contrast to conventional cars with internal combustion engines, electric cars are operated exclusively with lithium-ion batteries, so that the battery performance determines the overall performance of the car. However, slow load times and poor performance are still obstacles to overcome. With this in mind, a POSTECH research team recently developed a faster rechargeable and longer-lasting battery material for electric cars.
The research teams of Professor Byoungwoo Kang and Dr. Minkyung Kim from the Department of Materials Science and Engineering at POSTECH and Professor Won-Sub Yoon from the Department of Energy Science at Sungkyunkwan University have jointly proven for the first time that when charging and discharging Li-ion battery electrode materials, high performance is achieved by significantly shortening the charge – and discharge time can be generated without reducing the particle size. This research was published in the latest issue of Energy & Environmental Science, einer leading international journal in the field of energy materials.
Methods that reduce the particle size of the electrode materials have so far been used for the rapid charging and discharging of lithium-ion batteries. However, reducing the particle size has the disadvantage that the volumetric energy density of the batteries is reduced.
To this end, the research team confirmed that by forming an intermediate phase in the phase transition during charging and discharging, high power can be generated without the high energy density being lost or the particle size being reduced through fast charging and discharging, which leads to the development of long-life Li-ion batteries enables.
In the case of phase separation materials, which undergo the process of formation and growth of new phases during charging and discharging, two phases with different volumes exist within a single particle, which leads to many structural defects at the interface of the two phases. These defects inhibit the rapid growth of a new phase within the particle and thus impede rapid charging and discharging.
The synthesis method developed by the research team can induce an intermediate phase that acts as a structural buffer and can drastically reduce the volume change between the two phases in a particle.
In addition, it has been confirmed that this intermediate buffering phase can help create and grow a new phase within the particle, thereby improving the rate of onset and removal of lithium in the particle. This in turn proved that the formation of the interphase can dramatically increase the rate of charge and discharge of the cell by creating a homogeneous electrochemical reaction in the electrode, which is made up of numerous particles. As a result, the Li-ion battery electrodes synthesized by the research team charge up to 90% in six minutes and discharge 54% in 18 seconds, a promising sign of high-performance Li-ion battery development.
“The conventional approach has always been a compromise between its low energy density and the fast loading and unloading speed due to the reduction in particle size,” noted Professor Byoungwoo Kang, the corresponding author of the work. He continued: “This research laid the foundation for the development of Li-ion batteries that can achieve fast charging and discharging speeds, high energy density and extended performance.
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