Lithium-ion batteries, as high-energy-density energy storage devices, are widely used in portable electronic products such as mobile phones and laptops. Electric vehicles, which are currently attracting much attention, also rely heavily on lithium-ion batteries as a power source. This places even more stringent demands on the performance of lithium-ion batteries: higher energy density, longer lifespan, and a wider operating temperature window. However, graphite, currently a commercially available anode material for lithium-ion batteries, struggles to meet these requirements due to its relatively low theoretical capacity (~370 mAh/g). Therefore, researchers in related fields worldwide are searching for next-generation anode materials for lithium-ion batteries.
To address this issue, a research team led by Professor Wang Donghai of Pennsylvania State University, with Yu Zhaoxin and Song Jiangxuan as key members, recently invented a novel lithium-ion battery anode material: a red phosphorus-graphene nanocomposite material. This material is prepared by ball milling red phosphorus and graphite. Red phosphorus boasts high chemical stability, is inexpensive and readily available, and is environmentally friendly. Its theoretical capacity as a lithium-ion battery anode material can reach 2600 mAh/g, seven times that of commercially available graphite electrodes. Graphite/graphene, due to its extremely high electronic conductivity, was introduced into this system to enhance the overall electronic conductivity of the nanocomposite material. During high-speed ball milling, micron-sized red phosphorus particles are broken down to the nanoscale. Graphite is exfoliated into graphene with a large specific surface area during the ball milling process. After prolonged mechanical application, the graphene particles interlock to form a tightly bound three-dimensional conductive network, within which the nanoscale red phosphorus particles are uniformly dispersed. Infrared spectroscopy analysis revealed that red phosphorus and graphene are bonded together by phosphorus-oxygen-carbon (POC) chemical bonds, further ensuring the material's outstanding battery performance. At room temperature, this nanocomposite material exhibits a discharge capacity of 1400 mAh/g, four times that of graphite, a currently commercially available lithium-ion battery anode material. After 300 cycles, the discharge capacity remains above 60%. High-temperature environments (60°C) remain a significant challenge for current commercial lithium-ion batteries. However, this material achieves a discharge capacity of 1650 mAh/g at 60°C. After 200 cycles, the discharge capacity retention rate is above 70%.
High capacity, long lifespan, low-cost raw materials, and synthesis methods suitable for industrial production—these factors all contribute to making novel red phosphorus-graphene nanocomposites the preferred choice for next-generation lithium battery anode materials.
