Halide Solid‐State Electrolytes: Stability and Application for High Voltage All‐Solid‐State Li Batteries

Abstract

used in many batteries. Traditional Li-ion batteries have reached a point of development bottleneck due to their safety issues of the flammable liquid electrolytes and low energy density. [1,2] To meet the goal of manufacturing electronic vehicles, scientists are working on batteries that have a higher energy density and are safer. [3,4] All-solid-state Li batteries (ASSLBs), which are made up completely of solid components, are a promising candidate for future energy storage generation with better safety, [5][6][7][8] and higher energy density. [9][10][11] Solid electrolytes with good overall characteristics are critical for ASSLBs to be realized. [12] Several attempts have been undertaken in recent decades to build solid electrolytes with good Li + conductivity, such as polymer solid electrolytes, [13][14][15][16][17][18] sulfide solid electrolytes, [19][20][21] oxide solid electrolytes, [22][23][24][25][26][27][28] anti-perovskites, [29][30][31] and lithium phosphorous oxynitrides. [32][33][34][35][36] Oxide-based solid electrolytes, such as garnet and NASICON-type, have good chemical stability with cathode materials but are brittle and have a poor contact surface with the cathode, [37] and we may need to use a liquid electrolyte to improve interface wettability. [37][38][39][40] Considering their high Li + conductivity and ductility sulfide solid electrolytes have been extensively explored among the numerous types of solid electrolytes. [41][42][43][44][45] Li 10 GeP 2 S 12 (LGPS), for example, has a high ionic conductivity of more than 10 mS cm −1 , which is almost equivalent to those of the conventional liquid electrolytes. [43] On the other hand, sulfide-based solid electrolytes have poor hydrolysis stability, chemical instability issues with electrodes, and a narrow electrochemical window (ECW). [46][47][48] Sulfides are not chemically or electrochemically compatible with typical 4 V cathode active materials, [49,50] because they are oxidized at a low potential (≈2.5 V vs Li + /Li). [51][52][53] To solve these problems, particles of cathode active materials must be coated with chemically compatible, an ionically conductive, and electrically insulating material, [54] which leads to a myriad of new challenges. In this regard, numerous researchers have used several oxides as potential coating materials, such as

Solid-Electrolyte-Free O3-LixTiS2 Cathode for High-Energy-Density All-Solid-State Lithium-Metal Batteries

“…Although exhibiting higher capacities, the composite system shows greater voltage slip that may be associated with the previously reported increasing parasitic activity of the argyrodite SE at these potentials, which is further enhanced in this case due to the larger SE/AM contact area compared to the SE-free system. To test this hypothesis, we combined SE-free LTS with other electrolytes such as halide-type ones, some of which are known to be stable at these lower voltages, and no additional capacity at low potential was observed (Figure S6). Moreover, a comparison of the galvanostatic curve between the composite and SE-free cell (Figure a,c) reveals a striking difference in the high potential response, namely, the feasibility to remove 0.4 Li upon first charge for the composite electrode, as opposed to only 0.2 Li for the SE-free electrode.…”

Halide solid-state electrolytes for all-solid-state batteries: structural design, synthesis, environmental stability, interface optimization and challenges

“…96,100 However, as with other inorganic SSEs, halide electrolytes also need to overcome the interface problem with electrode materials. 20,142,143…”

“…96,100 However, as with other inorganic SSEs, halide electrolytes also need to overcome the interface problem with electrode materials. 20,142,143 6.1 Interfacial stability of halide SSEs and cathodes According to Wang et al's calculations, halide SSEs had a wide thermodynamic intrinsic electrochemical window, while suldes and oxides couldn't match it (Fig. 16a).…”

“…1). [17][18][19][20][21] Firstly, the weaker Coulomb force between halogen anions and Li ions and the wider Li ion transport channel formed by relatively larger radius halogen anions (Cl − = 167 pm, Br − = 182 pm, I − = 202 pm, O 2− = 126 pm and S 2− = 170 pm) 22,23 are conducive to ion mobility and guarantee the high ionic conductivity of halide SSEs (e.g., Li 3 ScCl 6 , 24 3.02 mS cm −1 ). Secondly, halide SSEs still possess good air stability and recoverability aer humidity exposure.…”

Research advance of lithium-rich cathode materials in all-solid-state lithium batteries

“…当前固态电解质体系可分为聚合物固态电解质和无机固态电解质。以聚环氧 乙烯(polyethylene oxide, PEO)为代表的聚合物固态电解质具有高可塑性、易加 工等优点，但室温锂离子电导率低(10 -8 −10 -6 S cm -1 )且需要高温运行等问题导 致其在富锂全固态锂电池应用上存在较大的瓶颈 [40] 。无机固态电解质如以 Li 7 P 3 S 11 、Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 、Li 10 GeP 2 S 12 、Li 6 PS 5 Cl 为代表的硫化物固态电解 质 [41] ，以 Li 3 YCl 6 、 Li 3 InCl 6 为 代 表 的 卤 化 物 固 态 电 解 质 [42] 和以钙 钛 矿 型 料安全性，镍元素提高材料能量密度，钴元素提高材料导电性和结构稳定性 [47] 。 在液态电池中，目前普遍以高镍或无钴作为发展目标 [48,49] 。而在固态电池中，由 于电子传输阻力较大，仍需要一定量的钴以提升材料的电子电导性。基于对富锂 正极材料本征特性的探究， Pan 等 [20] 通 过 调 整 0.5LiNi 0.33 Co 0.33+x Mn 0. 于在充电状态下由氧氧化还原反应触发的氧化氧) [18] ；(b) LRCox 和 LRCo10@yLN 正极的 电子电导率，离子电导率和 C2/m 相含量 [20] ；(c)(LPSCl+VGCF)|LPSCl|Li-In 电池在 2.0−4.8…”