摘要
水系钠离子电池电容器具有成本低、功率大、安全性好等优点,是下一代大规模储能系统的理想选择之一.本文采用Na0.44MnO2正极、活性炭(AC)负极、6 mol·L-1 NaOH电解液和廉价的不锈钢集流体构建了可充电碱性钠离子电池电容器.由于Na0.44MnO2正极在碱性电解液中具有较高的过充耐受性,通过首次充电时的原位过充预活化过程可以解决半钠化Na0.44MnO2正极和AC负极初始库伦效率低的缺点.因此,AC||Na0.44MnO2可充电碱性钠离子电池电容器具有优异的电化学性能,在功率密度为85 W·kg-1时,能量密度达26.6 Wh·kg-1,循环10000次后容量保持率为89%.同时,在50 ℃的高温和-20 ℃的低温也具有良好的电化学性能.这些结果表明AC||Na0.44MnO2可充电碱性钠离子电池电容器具备应用于大规模储能的潜力.
Abstract
As the most advanced battery technology to date,lithium-ion battery has occupied the main battery markets for electric vehicles and grid scale energy storage systems.However,the limited lithium reserves as well as the high price raise concerns about the sustainability of lithium-ion battery.Although sodium-ion battery is proposed as a good supplement to lithium-ion battery,expensive and flammable electrolyte components,harsh assembly environments and potential safety hazards have limited the rapid development to a certain extent.The organic electrolyte was replaced with an aqueous solution to construct a new type of aqueous sodium ion battery capacitor(ASIBC).It is of great significance for next-generation energy storage system owing to its low cost,high power,and inherent safety.However,applicable ASIBC system is rarely reported so far.Here,a rechargeable alkaline sodium ion battery capacitors constructed by using Na0.44MnO2 cathode,activated carbon(AC)anode,6 mol·L-1 NaOH electrolyte,and cheap stainless-steel current collector.Because of high overcharge tolerance of Na0.44MnO2 cathode in alkaline electrolyte,the shortcomings of the half-sodium Na0.44MnO2 cathode and low initial Coulombic efficiency of AC anode can be resolved by in situ overcharging pre-activation process during first charging.The available capacity of Na0.44MnO2 in half cell largely increased from～40 mAh·g-1(neutral electrolyte)to 77.3 mAh·g-1(alkaline electrolyte)due to broadened Na+ intercalation potential region.Thus,the AC||Na0.44MnO2 ASIBC delivers outstanding electrochemical properties with a high energy density of 26.6 Wh·kg-1 at a power density of 85 W·kg-1 and long cycling stability with a capacity retention of 89%after 10,000 cycles.The advantages of the alkaline electrolyte for the AC||Na0.44MnO2 ASIBC can be concluded as follows:(1)through the in situ electrochemical pre-activation process,the overcharging oxygen evolution reaction during first charging process can balance the adverse effects of the half-sodium Na0.44MnO2 cathode and low initial Coulombic efficiency of AC anode on the energy density of full cell;(2)the overcharging self-protection function can promote the generated oxygen to be eliminated at anode during overcharging,which improves the system safety;(3)the low-cost materials in alkaline environment can be scaled up to construct AC||Na0.44MnO2 ASIBC.In addition,the AC||Na0.44MnO2 ASIBC also possesses wide operating temperature range,achieving satisfied electrochemical performance at a high temperature of 50 ℃ and a low temperature of-20 ℃.Considering the merits of low-cost,high safety,no toxicity and environment-friendly,we believe the AC||Na0.44MnO2 rechargeable alkaline sodium-ion battery capacitors have the potential to be applied to large-scale energy storage.
基金项目
国家电网公司科技计划(5500-202158251A-0-0-00)
万方数据