High Rate and Long Lifespan Sodium‑Organic Batteries Using Pseudocapacitive Porphyrin Complexes‑Based Cathode

Sodium-organic batteries utilizing natural abundance of sodium element and renewable active materials gain great attentions for grid-scale applications.However,the development is still limited by lack of suitable organic cathode materials with high electronic conductivity that can be operated stably in liquid electrolyte.Herein,we present 5,15-bis(ethynyl)-10,20-diphenylporphyrin(DEPP)and[5,15-bis(ethynyl)-10,20-diphenylporphinato]copper(II)(CuDEPP)as new cathodes for extremely stable sodium-organic batteries.The copper(II)ion partially contributes the charge storage and significantly stabilizes the structure of porphyrin complex for electrochemical energy storage.In situ electrochemical stabilization of organic cathode with a lower charging current density was identified which enables both improved high energy density and power density.An excellent longterm cycling stability up to 600 cycles and an extremely high power density of 28 kW kg−1 were achieved for porphyrin-based cathode.This observation would open new pathway for developing highly stable sodium-organic cathode for electrochemical energy storage.

Thiophene-functionalized porphyrin complexes as high performance electrodes for sodium ion batteries

Organic sodium-ion batteries(OSIBs)using eco-friendly organic materials as electrodes have recently received much attention.However,the practical applications of OSIBs are generally limited by the inherent disadvantages of organic electrodes,such as their low conductivity,poor stability,and high solubility in electrolytes.Herein,we presented[5,10,15,20-tetrathienylporphinato]M(II)(MTTP,M=2H,Ni)as new electrode materials in sodium-organic batteries.The incorporation of thiophene functionalized groups and nickel(II)ion in the molecular design of porphyrins enabled stable and excellent electrochemical performance in sodium storage systems.Benefiting from multiple charge storage sites and bipolar characteristics,the NiTTP anode has a reversible capacity of 434 mAh g^(-1)at a current density of 25 mA g^(-1).An excellent long-term cycling stability and high average voltage were obtained when NiTTP was used as a cathode.In a symmetrical battery,where NiTTP was used as both cathode and anode materials,a high average voltage of 2.3 V and a practical energy density of 93 Wh kg^(-1)was achieved.These results suggest that the thiophene-based porphyrin derivatives would be promising electrode materials for long-term organic sodium ion batteries for green and stable energy storage.

固态锂金属电池用无枝晶锂负极的通用亲锂界面层的构建

固态锂金属电池具有高安全性和高能量密度的优势,被认为是最有前景的下一代电池体系.石榴石型固体电解质(LLZO)具有较高的离子电导率、良好的机械性能和对锂金属稳定等优点,成为当前的研究焦点.然而,固态电解质与金属锂之间较差的固固界面接触和界面处不均匀的锂沉积严重阻碍了固态电池的实际应用.本文提出一种改善固态电解质/锂负极界面润湿性的通用方法,通过在固态电解质表面滴加一层亲锂的氧化钴量子点,原位构建Co/Li_(2)O中间层.该方法不仅可以显著降低固态电解质与金属锂之间的界面阻抗,还可以调节界面处锂离子均匀沉积,有效抑制锂枝晶的生长.得益于原位构建的亲锂和导锂离子的Co/Li_(2)O中间层,当组装成锂对称电池时,其可在0.3 m A cm^(-2)的电流密度下稳定循环1696 h,且循环时过电位没有明显变化.匹配正极Li Fe PO_(4)(LFP)或Li_(1.4)Mn_(0.6)Ni_(0.2)Co_(0.2)O_(2.4)(LMNC622)的固态电池在25℃下能够稳定循环,且具有较高的放电比容量和库伦效率.