Researchers invent cell-like carbon microspheres to stably store potassium ions for battery negative electrodes

With the rapid development of smart portable electronic products and electric vehicles , the consumption of lithium resources will increase dramatically, which will also increase the cost of lithium-ion batteries (LIB). In addition, the shortage of lithium resources (only 0.0017 wt% in the earth's crust) and uneven distribution also limit its further development and application.

Potassium (2.7 wt% in the earth's crust) has similar properties to lithium and is abundant. As the best alternative to LIB, potassium-ion batteries (PIBs) have become a research focus. Compared with Na (2.71 V vs. standard hydrogen electrode/SHE), Mg (2.37 V vs. SHE), Al (1.66 V vs. SHE), etc., the standard redox potential of potassium (2.92 V vs. SHE) is closer to lithium (3.04 V vs. SHE). This means that PIB can provide higher energy density and discharge potential, which is of great significance for the future exploration of excellent electrode materials and the study of potassium storage mechanism.

According to foreign media reports, recently, in the latest journal of National Science Review, scientists from Hunan University, Central South University and Clemson University have jointly invented a cell-like carbon microsphere (BCC) that can stably store potassium ions. The bionic carbon battery (BCC) is composed of highly graphitized carbon sheets or carbon nanotubes.

(Image source: phys.org)

Carbon nanotubes are responsible for connecting the inside and outside of carbon batteries, providing a large number of ion channels, which increase the diffusion path of ions and improve the transmission rate. The internal space of BCCs provides a buffer for the volume change caused by the insertion of potassium ions into graphite, and the carbon shell of the cell membrane protects and supports the internal materials and the overall structure, greatly improving the cycle stability of PIB.

Experimental results show that the BCC-based electrode can be cycled 2100 times at a current density of 500 mA g-1, with a stable cycle capacity of 226 mAh g-1. At a current density of 100 mA g-1, it can operate continuously for more than 15 months, showing excellent cycle stability.

Professor Bingan Lu said: "From a scientific perspective, we have combined the fields of biology and material synthesis (biomimetic structures) and have seen the performance and stability of synthetic carbon materials as negative electrodes for potassium ion batteries. From a broader perspective, this research has introduced a new solution to improve battery performance and provides a new path for the design and manufacture of new biomimetic battery materials in the future."