| Lithium-ion batteries have attracted much attention because of their high efficiency and reversible energy storage performance.However,the lack of lithium resources and the greater difficulty of development hinder the long-term development of lithium-ion batteries.Potassium,which is in the same main group as lithium,has similar physical and chemical properties of lithium and accessible.Therefore,potassium ion batteries are expected to become an advantageous alternative to lithium ion batteries in certain areas.Electrode materials are the key to secondary batteries,and it is very important to design and synthesize materials with excellent performance.Carbon materials are regarded as promising anode materials for lithium and potassium ion batteries due to their excellent physical and chemical properties,safety and reliability,etc.Coal and its derivatives,coal tar pitch,are considered as a high-quality carbon source for preparing electrode materials due to its richness in various elements and easy removal of impurities.Based on this,this paper focuses on the use of cheap coal and coal tar pitch,through green and environmentally friendly means,to achieve the preparation of coal-based electrode materials and the full use of the high added value of coal-based materials.The main research contents are summarized as follows:（1）Using pulverized coal as the carbon source and sodium sulfate as the sulfur source,the high-temperature solid-phase method was used to successfully synthesize sulfur-doped coal-based porous carbon with a three-dimensional porous network structure.The successful incorporation of sulfur and the hierarchical porous structure make the material have a higher defect concentration and a stable structure.As a negative electrode material for potassium ion batteries,it exhibits a reversible capacity of 259 m Ah g-1 at a current density of 50 m A g-1,and can still maintain 71.9%of the initial capacity after 200 cycles.As a negative electrode material for lithium-ion batteries,it exhibits a lithium storage capacity of 651 m Ah g-1 at a current density of100 m A g-1.（2）Using coal tar pitch and sodium bicarbonate as raw materials,the preparation of porous carbon nanosheets with uniform pore distribution was successfully realized.Abundant holes and nano-sized carbon sheets can provide guarantee for the rapid wetting of the electrolyte and the stability of the material structure,so that the material exhibits excellent electrochemical performance.As a negative electrode material for lithium-ion batteries,at a current density of 100 m A g-1,the initial charge capacity is 518 m Ah g-1,and a reversible capacity of 212 m Ah g-1 remains after 500cycles at a current density of 1 A g-1.For its full battery performance test,at a current density of 100 m A g-1,the full battery showed a reversible capacity of 233 m Ah g-1.（3）Using coal tar pitch,sodium carboxymethyl cellulose and ammonium chloride as raw materials,synthesis of nitrogen-doped porous carbon.The rich pore structure greatly reduces the damage to the material structure during the de-embedding process.In addition,the successful incorporation of nitrogen causes more defects in the material,increases ion storage sites and accelerates electron transport,and improves the electrochemical performance of the battery.As a negative electrode material for lithium-ion batteries,it exhibits a charge capacity of 770 m Ah g-1 at a current density of 100 m A g-1,and a reversible capacity of 551 m Ah g-1 at a current density of 1A g-1.As a negative electrode material for a potassium ion battery,it exhibits a charge capacity of 312 m Ah g-1 at a current density of 50 m A g-1,and a reversible capacity of 214 m Ah g-1 after 50 cycles.There are 69 figures,5 tables and 127 reference in this paper. |
PDF Full Text Request