Chen Zhen, Gao Xinpei, Kim Jae-Kwang, Kim Guk-Tae, Passerini Stefano
Helmholtz Institute Ulm (HIU), 89081 Ulm, Germany.
Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany.
ACS Appl Mater Interfaces. 2021 Nov 17;13(45):53810-53817. doi: 10.1021/acsami.1c14487. Epub 2021 Nov 5.
NASICON-type LiAlTi(PO) (LATP) is a promising solid electrolyte (SE) candidate for next-generation solid-state batteries. However, its use in solid-state composite electrodes is inhibited by its stiffness, which results in poor interparticle contact unless high-temperature treatments are applied. The poor LATP-LATP and LATP-active material in the positive electrode (cathode) composite produced at ambient temperature yield poor ionic conductivity, impeding the electrode's performance. Herein, we focus on the optimization of the electrochemical performance of LiNiCoMnO (NCM)-LATP composite electrodes made by tape casting, taking advantage of a small fraction of an ionic liquid electrolyte (ILE) filling the composite cathode porosity. The incorporated LATP particles are found to closely surround the large NCM secondary particles, partially filling the composite electrode pores and resulting in a porosity reduction from 37 vol % (NCM only) to 32 vol % (NCM-LATP). After filling up the majority of the electrode porosity with ILE, the NCM-LATP composite electrodes offer improved capacity retention upon both long-term cycling tests (>99.3% after 200 cycles) and high-rate tests (>70% at 2 C-rate), due to the more stable LATP|NCM interface, and facilitated Li diffusion in the composite electrode bulk. Results obtained from proof-of-concepts monopolar (3.0-4.3 V) and bipolar-stacked (6.0-8.6 V) cells are reported.
NASICON型LiAlTi(PO)（LATP）是下一代固态电池中一种很有前景的固体电解质（SE）候选材料。然而，其刚度限制了它在固态复合电极中的应用，除非进行高温处理，否则会导致颗粒间接触不良。在室温下制备的正极（阴极）复合材料中，LATP-LATP以及LATP与活性材料之间的接触较差，导致离子电导率较低，从而阻碍了电极性能。在此，我们重点优化通过流延成型制备的LiNiCoMnO（NCM）-LATP复合电极的电化学性能，利用一小部分离子液体电解质（ILE）填充复合阴极孔隙。研究发现，掺入的LATP颗粒紧密围绕着较大的NCM二次颗粒，部分填充了复合电极孔隙，使孔隙率从37体积%（仅NCM）降至32体积%（NCM-LATP）。在用ILE填充了大部分电极孔隙后，NCM-LATP复合电极在长期循环测试（200次循环后>99.3%）和高倍率测试（2 C倍率下>70%）中都表现出更好的容量保持率，这归因于更稳定的LATP|NCM界面以及复合电极本体中Li扩散的促进。本文还报道了从概念验证单极（3.0 - 4.3 V）和双极堆叠（6.0 - 8.6 V）电池获得的结果。
