Stability of garnet-type Li ion conductors: An overview

Synthesis and Properties of NaSICON‐type LATP and LAGP Solid Electrolytes

“…Suc-cessfule xamples in oxidesi nclude garnet oxides, [15,16] perovskite-type oxides, [17,18] and antiperovskite oxides. [2,6,[37][38][39][40] NaSICON-type solid electrolytes, such as LATP and LAGP, have marked advantages compared with sulfides and oxides: they display chemicals tabilityi na ir and/or water,a re low cost and low toxicity,a nd have great electrochemical stability with the added benefito fe asy preparation. [29][30][31] Popular phosphate solid electrolytes include sodium superionic conductor (NaSICON)structured lithium-ion conductors, [32][33][34][35][36] such as LiTi 2 (PO 4 ) 3 (LTP), Li 1 + x Al x Ti 2Àx (PO 4 ) 3 (LATP), and Li 1 + x Al x Ge 2Àx (PO 4 ) 3 (LAGP).…”

“…[19][20][21] Sulfide solid electrolytes include Li 2 SÀP 2 S 5 , [22,23] Li 3 PS 4 , [24][25][26] Li 7 P 3 S 11 , [27,28] Li 7 PS 6 ,a nd Li 6 PS 5 X( X = Cl, Br). [2,6,[37][38][39][40] NaSICON-type solid electrolytes, such as LATP and LAGP, have marked advantages compared with sulfides and oxides: they display chemicals tabilityi na ir and/or water,a re low cost and low toxicity,a nd have great electrochemical stability with the added benefito fe asy preparation. Many exciting discoveries of these materials have been summarized in important review papers.…”

“…Many exciting discoveries of these materials have been summarized in important review papers. [2,6,[37][38][39][40] NaSICON-type solid electrolytes, such as LATP and LAGP, have marked advantages compared with sulfides and oxides: they display chemicals tabilityi na ir and/or water,a re low cost and low toxicity,a nd have great electrochemical stability with the added benefito fe asy preparation. [2,36,38] They also exhibit attractive ionic conductivities of 10 À4 -10 À3 Scm À1 at room temperature.…”

Interface‐Engineered Li7La3Zr2O12‐Based Garnet Solid Electrolytes with Suppressed Li‐Dendrite Formation and Enhanced Electrochemical Performance

“…As a promising inorganic SE, lithium garnet‐type Li 7 La 3 Zr 2 O 12 , discovered by Thangadurai, Weppner, and Murugan in 2007, has been intensively studied because of its high chemical stability, wide electrochemical stability window, good mechanical properties, and relatively high ionic conductivity . The major challenges for the practical use of garnet‐type SEs in all‐solid‐state LIBs include:, 1) the large interfacial resistance between SE and electrode due to the rigid ceramic nature of Li 7 La 3 Zr 2 O 12 and formation of Li 2 CO 3 by air absorption; 2) poor interfacial wetting between Li metal and Li 7 La 3 Zr 2 O 12 preventing intimate physical contact; and 3) formation of Li dendrites owing to uneven deposition of Li metal, which may penetrate the SE and short batteries. Additionally, the rigid nature of the oxide electrolyte causes very poor contact between cathode and electrolyte, and thus leads to a high interfacial resistance.…”

Recent Advancements in Interface between Cathode and Garnet Solid Electrolyte for All Solid State Li-ion Batteries

“…Key words: inorganic solid state electrolyte; composite electrolyte; interfacial wettability; interfacial impendence; interface modification; review 全固态锂离子电池在解决传统锂离子电池使用 温度范围窄、能量密度低、使用寿命短、安全等级 低等关键问题的同时, 有望大幅降低电池制造成 本、有效改善电池的安全性问题, 在动力电池和大 容量新型储能方面具有广阔的应用前景 [1][2][3][4][5][6][7][8] 。 固体电解质作为全固态锂离子电池的重要组成 部分, 其性能的优劣很大程度上制约着全固态电池 实际应用的发展 [9][10][11][12] 。固体电解质分为无机固体电 解质和聚合物固体电解质。相对于聚合物固体电解 质容易结晶、适用温度范围窄以及力学性能提升难 的问题, 无机固体电解质能在宽的温度范围内保持 良好的化学稳定性、电化学稳定性、力学性能和更 高的安全特性 [13][14][15][16] 。图 1 为室温下, 不同结构类型 无机固体电解质的离子电导率, 从图中可以看出类 Lisicon 型以及 Argyrodite 型的固体电解质具有与液 体电解质相近的电导率 [17] , 但这些含硫化合物存在 对水分比较敏感、化学稳定性欠佳、易挥发、难以合 成所需计量化合物 [18] 和电压窗口窄 [19] 等问题, 在全 固态电池的应用中受到较大的限制。具有高电导率 的石榴石型电解质, 如 Li 7 La 3 Zr 2 O 12 [20][21][22][23] (LLZO)以 及元素掺杂后的 LLZO 室温电导率可达 10 -3 S·cm -1 数量级 [24] , 与金属 Li 有相对稳定的界面, 且在空气 中也有着良好的化学稳定性, 因而石榴石型电解质 在全固态电池研究和开发中有着良好的应用前景。 目前, 电极与固体电解质间的高界面阻抗使得全固 态锂离子电池的容量、倍率和循环性能都不理想。 图 1 室温下不同类型固体电解质的电导率 [17] Fig. 1 Conductivity of different types of solid electrolytes at room temperature [17] 全固态电池体系的界面主要包括正极/固体电解质 界面和负极/固体电解质界面 [25][26][27][28][29][30] , 本文以正极与 LLZO 石榴石型固体电解质界面为研究对象, 从正 极/石榴石型固体电解质的界面特性、界面研究中存 在的问题、以及界面改性等方面进行概述。 1 正极/石榴石型固体电解质界面特 [31] , 导 致电解质/正极接触面积较小, 并在界面处形成一定 的结构缺陷(如: 空隙 [32] 、 裂纹 [33] ), 制约了锂离子在 界面上的传输速率, 形成了高的界面阻抗。 另外, 电 池在充放电循环过程中, 电极材料与固体电解质自 身结构的变化和界面区域第三相的形成, 导致界面 处产生一定的结构应力, 随着循环的进行, 应力累 加使界面断裂、 分离, 最终导致全固态电池失效 [34][35] …”