【摘要】 尖晶石镍锰酸锂材料(LiNi_0.5Mn_1.5O₄、LNMO)有着高充放电电压平台（约4.7 V）,可提供约250 Wh·kg^-1的能量密度，成本相对较低，符合高能量密度电池的要求。高电压平台的LNMO正极对电解液有着更加苛刻的要求，高电压下传统电解液中碳酸酯类易分解，酸性产物以及电池中痕量水不断促进分解反应正向进行，侵蚀正极材料增大阻抗，严重影响电池性能。本工作引入价格低廉的双三甲基硅氧基甲基硅烷（HTMS）作为高电压添加剂，HTMS中的硅氧键（Si—O）可结合酸性产物，减缓其对正极材料的腐蚀，同时电解液配方中氟代碳酸乙烯酯（FEC）配合HTMS巩固电极-电解液之间的界面，形成含氟化锂（LiF）、有机硅化合物的低阻抗界面层。组装的Li/LNMO电池在5 V下以1C循环100圈后有着120.78 mAh·g^-1的高容量，同时电池在-20℃特种低温环境下仍可1C循环200圈，比容量也高达103.96 mAh·g^-1,明显优于传统电解液。这项工作为5.0 V高电压下的锂离子电池特种电解液配方设计提供了新的方向。更多还原

【Abstract】 High-energy density batteries can be met by lithium nickel manganese spinel material(LiNi_0.5Mn_1.5O₄, LNMO), which has a high charge/discharge voltage platform（approximately 4.7 V） and can produce an energy density of roughly 250 Wh·kg^-1 at a reasonable cost. The electrolyte needs are more stringent on the high voltage platform of the LNMO cathode. The carbonate ester in the conventional electrolyte decomposes easily at high voltages, and the battery’s acidic products and trace water constantly encourages the decomposition reaction in the positive direction. This erodes the cathode material and raises the impedance, which has a negative impact on the battery performance. In our work, the low-cost heptamethyltrisiloxane（HTMS） is introduced as a 5.0 V high-voltage additive. The silicon-oxygen bond（Si—O） in HTMS could combine the acidic products to slow down the corrosion of cathode materials. Meanwhile, the electrolyte formulation’s fluorinated ethylene carbonate（FEC） was used in conjunction with HTMS to consolidate the electrode-electrolyte interface and formed a low-impedance interfacial layer containing LiF, organosilicon, and silicone compounds. At a specific low temperature of-20 ℃, the Li/LNMO battery still moke cycled for 200 cycles at 1C, with a high specific capacity of 103.96 mAh·g^-1 at 5 V. The battery had a high capacity of 120.78 mAh·g^-1 after 100 cycles at 1C. The performance was significantly better than that of conventional electrolytes. This work provides a new direction for the design of special electrolyte formulations for high voltage lithium ion batteries at 5 V.更多还原