Nitrogen and phosphorous co-doped hierarchical meso–microporous carbon nanospheres with extraordinary lithium storage for highperformance lithium-ion capacitors

高储锂性能的氮、磷共掺杂分级多孔炭纳米球用于高比能锂离子电容器

Lithium-ion capacitors(LICs),consisting of a battery-like negative electrode and a capacitive porous-carbon positive electrode,deliver more than twice the energy density of electric double-layer capacitors.However,their wide application suffers from low energy density and reduced cycle life at high rates.Herein,hierarchical meso±microporous carbon nanospheres with a highly disordered structure and nitrogen/phosphorous co-doped properties were synthesized through a facile template method.Such hierarchical porous structure facilitates rapid ion transport,and the highly disordered structure and high heteroatom content provide abundant active sites for Li+charge storage.Electrochemical experiments demonstrated that the carbon nanosphere anode delivers large reversible capability,greatly improves rate capability and exhibits excellent cycle stability.An LIC fabricated with the carbon nanosphere anode and an activated carbon cathode yields a high energy density of 103 W h kg^(-1),an extremely high power density of 44,630 W kg^(-1),and longterm cyclability of over 10,000 cycles.This work presents how structural control of carbon materials at the nano/atomic scale can significantly enhance electrochemical performance,enabling new opportunities for the design of high-performance energy-storage devices.

锂离子电容器通常由一个电池型负极和一个电容型多孔炭正极组成,可输出比传统双电层电容器高两倍的能量密度,但是在高倍率条件下其能量密度低、循环寿命短,因而其广泛应用受到阻碍.本文通过模板法合成了一种结构高度无序、氮/磷共掺杂的分级介孔炭纳米球.这种分级多孔结构有利于锂离子的快速迁移,且高度无序的结构和高杂原子含量为锂离子电荷存储提供了丰富的活性位点.电化学测试表明,该炭纳米球负极具有较高比容量(在0.1 A g^(-1)时,为1108.6 mA h g^(-1)),优异的倍率性能(在8 A g^(-1)时,为276.5 mA h g^(-1)),以及良好的循环稳定性(1000次循环后仍保持85%的容量).以该分级多孔纳米球为负极,自制活性炭为正极所组装的锂离子电容器具有较高的能量密度(103 W h kg^(-1))、功率密度(44,630 W kg^(-1))以及长循环寿命(>10,000圈).该工作揭示了如何通过在纳米/原子尺度上调控炭材料微结构来提高电化学性能的方法,为设计高性能的储能设备提供了新策略.