Development of Sulfide Solid Electrolytes and Interface Formation Processes for Bulk-Type All-Solid-State Li and Na Batteries
Development of Sulfide Solid Electrolytes and Interface Formation Processes for Bulk-Type All-Solid-State Li and Na Batteries
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DOI：
10.3389/fenrg.2016.00025
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发表时间：
2016-07-15
影响因子：
3.4
通讯作者：
Tatsumisago, Masahiro
中科院分区：
文献类型：
--
作者：
Hayashi, Akitoshi;Sakuda, Atsushi;Tatsumisago, Masahiro
采用无机固体电解质（SEs）的全固态电池因其高安全性、多用途的几何形状和良好的循环寿命而被公认为可充电电池的终极目标。与薄膜电池相比，使用电极活性材料颗粒来增加块状全固态电池的可逆容量是困难的，因为电极和电解质颗粒之间的固-固界面接触面积有限。硫化se具有高导电性、宽电化学窗口和适当的力学性能（如成形性、加工性和弹性模量）等优点。具有Li7P3S11晶体的硫化物电解质在25℃时具有1.7x10(-2) S cm（-1）的高Li+离子电导率，远远超出常规有机液体电解质的Li+离子电导率。在具有立方结构的Na3.06P0.94Si0.06S4中，Na+离子的电导率达到7.4 × 10(-4) S cm（-1）。此外，在电极和电解质之间形成良好的固-固界面是实现固态电池的重要条件。硫化物电解质比氧化物电解质具有更好的成形性。因此，仅通过冷压而不进行热处理的硫化物的“室温烧结”，就可以实现致密的电解质分离器和与活性物质颗粒紧密连接的界面。硫化物电解质的弹性模量小于氧化物电解质，Na2S-P2S5玻璃电解质的杨氏模量小于Li2S-P2S5电解质。正极层的SEM横截面观察表明，活性材料颗粒表面的硫化物电解质涂层即使在最小电解质体积下也增加了界面面积，表明体型固态电池的能量密度得到了提高。电极颗粒的表面涂覆和纳米复合材料的制备都能有效地提高电池的可逆容量。我们的方法形成固体-固体界面进行了演示。
All-solid-state batteries with inorganic solid electrolytes (SEs) are recognized as anultimate goal of rechargeable batteries because of their high safety, versatile geometry, and good cycle life. Compared with thin-film batteries, increasing the reversible capacity of bulk-type all-solid-state batteries using electrode active material particles is difficult because contact areas at solid-solid interfaces between the electrode and electrolyte particles are limited. Sulfide SEs have several advantages of high conductivity, wide electrochemical window, and appropriate mechanical properties, such as formability, processability, and elastic modulus. Sulfide electrolyte with Li7P3S11 crystal has a high Li+ ion conductivity of 1.7x10(-2) S cm(-1) at 25 degrees C. It is far beyond the Li+ ion conductivity of conventional organic liquid electrolytes. The Na+ ion conductivity of 7.4x10(-4) S cm(-1) is achieved for Na3.06P0.94Si0.06S4 with cubic structure. Moreover, formation of favorable solid-solid interfaces between electrode and electrolyte is important for realizing solid- state batteries. Sulfide electrolytes have better formability than oxide electrolytes. Consequently, a dense electrolyte separator and closely attached interfaces with active material particles are achieved via "room-temperature sintering" of sulfides merely by cold pressing without heat treatment. Elastic moduli for sulfide electrolytes are smaller than that of oxide electrolytes, and Na2S-P2S5 glass electrolytes have smaller Young's modulus than Li2S-P2S5 electrolytes. Cross-sectional SEM observations for a positive electrode layer reveal that sulfide electrolyte coating on active material particles increases interface areas even with a minimum volume of electrolyte, indicating that the energy density of bulk-type solid-state batteries is enhanced. Both surface coating of electrode particles and preparation of nanocomposite are effective for increasing the reversible capacity of the batteries. Our approaches to form solid-solid interfaces are demonstrated.