石墨烯对La-Mg-Ni基储氢合金电化学性能的影响

为提高La-Mg-Ni基储氢合金La_(0.73)Ce_(0.18)Mg_(0.09)Ni_(3.20)Al_(0.21)Mn_(0.10)Co_(0.60)的电化学性能,将制备的石墨烯添加到储氢合金中。经XRD分析可知,处理前后合金的相结构没有变化。添加质量分数为1%、2%、5%石墨烯的合金电极与未添加石墨烯电极相比,最大放电容量略有下降,但50次循环后的放电容量保持率从63%分别提高到75%、78%和73%。添加2%石墨烯电极和未添加石墨烯电极相比,900 m A/g放电电流密度下的高倍率放电容量保持率从79.8%增加到83.9%,交换电流密度I0从54 m A/g提高到281 m A/g,极限电流密度IL从512 m A/g提高到1 537 m A/g。加入石墨烯后,电极的抗腐蚀性能也明显增强。

Effect of Graphene on Electrochemical Properties of the La-Mg-Ni-based Hydrogen Storage Alloy

In order to improve the electrochemical properties of La-Mg-Ni system hydrogen storage alloy, graphene was synthesized and added into the hydrogen storage alloy La0.73Ce0.18Mg0.09Ni3.20Al0.21Mn0.10Co0.60. It was found that the alloy still retained the phase structure. Electrochemical studies showed that the maximum discharge capacity of these electrodes decreased slightly. After adding 1%, 2% and 5% grapheme, the cyclic capacity retention rate after 50 charge-discharge cycles was significantly enhanced from 63% of original alloy to 75%, 78% and 73%. As the graphene content was 2%, the high rate dischargeability (HRD) at the discharge current density of 900 mA/g increased from 79.8% to 83.9%, and the exchange current density I0 and the limiting current density IL improved from original 54 mA/g and 512 mA/g to 281 mA/g and 1537 mA/g, respectively. Furthermore, the addition of graphene had a positive effect on the anti-corrosion capability of electrodes.