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

Universal lithiophilic interfacial layers towards dendrite-free lithium anodes for solid-state lithium-metal batteries

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.

Solid-state lithium-metal-batteries(SSLMBs)using garnet Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)(LLZTO)as the solid electrolyte are expected to conquer the safety concerns of high energy Li batteries with organic liquid electrolytes owing to its nonflammable nature and good mechanical strength.However,the poor interfacial contact between the Li anode and LLZTO greatly restrains the practical applications of the electrolyte,because large polarization,dendritic Li formation and penetration can occur at the interfaces.Here,an effective method is proposed to improve the wettability of the LLZTO toward lithium and reduce the interfacial resistance by engineering universal lithiophilic interfacial layers.Thanks to the in-situ formed lithiophilic and ionic conductive Co/Li_(2)O interlayers,the symmetric Li/CoO-LLZTO/Li batteries present much smaller overpotential,ultra-low areal specific resistance(ASR,12.3 X cm^(2)),high critical current density(CCD,1.1 mA cm^(-2)),and outstanding cycling performance(1696 h at a current density of 0.3 mA cm^(-2))at 25℃.Besides,the solid-state Li/CoO-LLZTO/LFP cells deliver an excellent electrochemical performance with a high coulombic efficiency of~100%and a long cycling time over 185 times.Surprisingly,the high-voltage(4.6 V)solid state Li/CoO-LLZTO/Li_(1.4)Mn_(0.6)Ni_(0.2)Co_(0.2)O_(2.4)(LMNC622)batteries can also realize an ultra-high specific capacity(232.5 mAh g-1)under 0.1 C at 25℃.This work paves an effective way for practical applications of the dendrite-free SSLMBs.