【电化学专题】提高固态电池离子传导性的妙招

Interfacial engineering of solid electrolytes

   文中部分图片：

空间电荷的形成

Fig. 1. Schematic illustration of the formation of space charges at (a) a free surface (or an interface with an inert phase, with negligible space charges on the other side) and (b) a symmetrical grain boundary (GB). In both cases, it is assumed that the interfacial cores are positively charged and there are (only) two oppositely-charged defects, both of which are sufficiently mobile to redistribute in the space-charge zone to obey the Poisson-Boltzmann equation.

氧化钇稳定氧化锆的空间电荷模型

Fig. 2. Schematic illustration of the space-charge model for YSZ at low temperatures (<∼1000 °C), where the acceptors are assumed to be constant (immobile) and the Mott-Schottky approximation is presumably held [15]. This low-temperature case is of direct importance for understanding the high GB resistivity.

界面相

Fig. 3. (a) HRTEM image of a Li4P2O7-based, nanometer-thick IGF and an analogous surface phase (SAFs) observed in LiFePO4, which may provide a fast Li+ conduction pathway [35], [56], [64]. (b) Schematic of a series of 2-D interfacial phases (Dillon–Harmer complexions), which may be interpreted as derivatives of IGFs with discrete (nominal) thicknesses of 0, 1, 2, 3, x and +∞ monolayers, respectively. These interfacial phases (complexions) are thermodynamically 2-D (a.k.a. the thorough-thickness compositional and structural profiles are thermodynamically-determined so there is no degree of freedom in this perpendicular direction); their formation and transition can drastically change both the space-charge profile (via changing Q0) and ionic mobility along the interfaces (via inducing interfacial disordering).

受主掺杂的ZrO2 和CeO2的晶界结构

Fig. 4. Schematic illustration of the GB configurations in acceptor-doped ZrO2 and CeO2. (a) In the “intrinsic” case, GBs are atomically sharp and positively charged. Space-charge zones with severe depletion of oxygen vacancies can form at low temperatures where the Mott-Schottky approximation is assumed (Fig. 2), leading to high GBresistivity; this GB blocking effect may disappear at T > ∼1000 °C [15]. (b) Practically, the presence of nanometer-thick, siliceous IGFs can further increase the GB resistivity (substantially) because such glass-like IGFs are considered highly insulating to oxygen vacancies/ions. Two remediating strategies, namely (1) post-sintering annealing at a relatively low T (∼1300 °C) to “dewet” and (2) reducing the μ of SiO2 to scavenge theses siliceous IGFs, can be employed [103]; both are examples of using GB transitions (via changing the complexion stability by changing the thermodynamic potential T or μ) to alleviate the detrimental effects.

热动力起源

Fig. 5. Schematic illustration of a possible thermodynamic origin of the resistive TiO2−x-like GB complexion in LLTO observed by Ma et al. [104], which may be interpreted as a case of GB prewetting.

晶界相促进质子传输

这篇观点独到的综述是由加州大学的Jian LUO老师撰写，让我们来认识下他吧！

Jian Luo graduated from Tsinghua University with dual Bachelor's degrees. After receiving his M.S. and Ph.D. degrees from MIT, he worked in the industry for more than two years with Lucent Technologies and OFS/Fitel. In 2003, Luo joined the Clemson faculty, where he served as an Assistant/Associate/Full Professor of Materials Science and Engineering. In 2013, he moved to UCSD as a Professor of NanoEngineering and Professor of Materials Science and Engineering. Luo chaired the Basic Science Division of the American Ceramic Society for 2012–2013, and he was named as a National Security Science and Engineering Faculty Fellow in 2014.