表面氧化和插层改性硬碳负极锂离子电容器

A high-rate and ultrastable anode for lithium ion capacitors produced by modifying hard carbon with both surface oxidation and intercalation

由于锂离子电容器正负极材料的储能机理不同,正极材料对其功率密度和倍率性能有很大限制。硬炭是一种很有前景的锂离子电容器负极材料,对炭材料进行改性是提高锂离子电容器电化学性能的重要手段之一。本研究采用氧化插层法制备的硬炭插层复合材料(ZnCl_(2)―OHC),0.05 A·g^(−1)电流密度下半电池可逆容量为257.4 mAh·g^(−1)。ZnCl_(2)―OHC作负极、活性炭作正极的全电池容量保持可达43.3%,比未经处理硬炭作负极的全电池提高了2倍以上,1 A·g^(−1)电流密度下充放电5000次后容量保持率约为98.4%。因此,通过硬炭的表面氧化和插层改性可以作为未来提升锂离子电容器负极性能的一种途径。

Due to the difference of energy storage mechanisms between the anode and cathode materials,the power density or rate performance of a lithium-ion capacitor is greatly limited by its anode material.Hard carbon is a promising anode material for lithium ion capacitors,and its modification is an important way to improve the electrochemical performance of lithium-ion capacit-ors.A commercial hard carbon from Kuraray Inc was modified by oxidation followed by intercalation with ZnCl_(2)(ZnCl_(2)―OHC).The reversible capacity of a half-cell prepared using this material was 257.4 mAh·g^(−1) at 0.05 A·g^(−1),which is obviously higher than the unmodified one(172.5 mAh·g^(−1)).The capacity retention of a full cell prepared using ZnCl_(2)―OHC as the anode and activated carbon as the cathode reached 43.3%when the current density increased from 0.1 to 10 A·g^(−1),which is more than twice that of the untreated hard carbon.After 5000 charge-discharge cycles at 1 A·g^(−1),the capacity retention of the full cell was about 98.4%.The modification of hard carbon by surface oxidation and intercalation is therefore a promising way to improve its anode performance for lithium ion capacitors.