New Insights into the Effects of Zr Substitution and Carbon Additive on Li3-xEr1-xZrxCl6 Halide Solid Electrolytes.
New Insights into the Effects of Zr Substitution and Carbon Additive on Li3-xEr1-xZrxCl6 Halide Solid Electrolytes.
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DOI：
10.1021/acsami.1c25087
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发表时间：
2022-02
影响因子：
9.5
通讯作者：
Qinong Shao;Chenhui Yan;M. Gao;Wubin Du;Jian Chen;Yaxiong Yang;Jiantuo Gan;Zhijun Wu;Wenping Su
中科院分区：
文献类型：
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作者：
Qinong Shao;Chenhui Yan;M. Gao;Wubin Du;Jian Chen;Yaxiong Yang;Jiantuo Gan;Zhijun Wu;Wenping Su
卤化物固体电解质由于其适度的离子电导率以及与氧化物正极材料良好的界面相容性，被认为是实用高压全固态锂离子电池（ASSLIB）最有前途的候选者。异价离子掺杂是提高卤化物电解质离子电导率的有效策略。然而，离子掺杂对卤化物电解质电化学稳定性窗口和碳添加剂对电化学性能的影响目前仍不清楚。本文通过机械化学方法合成了一系列Zr掺杂的Li3-xEr1-xZrxCl6卤化物固体电解质（SEs），并系统研究了Zr取代对离子电导率和电化学稳定性窗口的影响。 Zr掺杂可以提高离子电导率，同时缩小Li3ErCl6电解质的电化学稳定性窗口。优化后的Li2.6Er0.6Zr0.4Cl6电解质表现出1.13 mS cm-1的高离子电导率和4.21 V的高氧化电压。此外，碳添加剂被证明有利于卤化物基ASSLIB实现高放电容量、更好的循环稳定性和倍率性能，这与硫化物电解质的情况完全不同。具有未涂层 LiCoO2 正极和碳添加剂的 ASSLIB 具有 147.5 mAh g-1 的高放电容量和卓越的循环稳定性，500 次循环后容量保持率为 77%。这项工作深入了解了离子掺杂和碳添加剂对卤化物固体电解质的影响，并提供了实现高能量密度 ASSLIB 的可行策略。
Halide solid electrolytes have been considered as the most promising candidates for practical high-voltage all-solid-state lithium-ion batteries (ASSLIBs) due to their moderate ionic conductivity and good interfacial compatibility with oxide cathode materials. Aliovalent ion doping is an effective strategy to increase the ionic conductivity of halide electrolytes. However, the effects of ion doping on the electrochemical stability window of halide electrolytes and carbon additive on electrochemical performance are still unclear by far. Herein, a series of Zr-doped Li3-xEr1-xZrxCl6 halide solid electrolytes (SEs) are synthesized through a mechanochemical method and the effects of Zr substitution on the ionic conductivity and electrochemical stability window are systematically investigated. Zr doping can increase the ionic conductivity, whereas it narrows the electrochemical stability window of the Li3ErCl6 electrolyte simultaneously. The optimized Li2.6Er0.6Zr0.4Cl6 electrolyte exhibits both a high ionic conductivity of 1.13 mS cm-1 and a high oxidation voltage of 4.21 V. Furthermore, carbon additives are demonstrated to be beneficial for achieving high discharge capacity and better cycling stability and rate performance for halide-based ASSLIBs, which are completely different from the case of sulfide electrolytes. ASSLIBs with uncoated LiCoO2 cathode and carbon additives exhibit a high discharge capacity of 147.5 mAh g-1 and superior cycling stability with a capacity retention of 77% after 500 cycles. This work provides an in-depth understanding of the influence of ion doping and carbon additives on halide solid electrolytes and feasible strategies to realize high-energy-density ASSLIBs.