Molten carbonate electrolysis cells (MCEC) are a promising electrochemical CO₂ capture and conversion process. However, the CO₂ absorption and energy efficiencies are limited by the sluggish CO₂ absorption kinetics and high electrode overpotentials. Herein, we propose an electrolyte engineering strategy to improve the CO₂ absorption rate and reduce overpotentials at both the anode and the cathode. When BO₃³⁻ was added into molten Li₂CO₃-Na₂CO₃-K₂CO₃, the CO₂ adsorption efficiency was improved from 3.3% to 60%, the overpotential was reduced by ∼ 567 mV at the cathode and by ∼ 238 mV at the anode under 200 mA cm⁻². Accordingly, the energy efficiency reached 76.2 % at 650 °C. The improved CO₂ absorption and energy efficiencies are thanks to the BO₃³⁻ that changes the thermodynamic properties of the molten carbonate, i.e., the BO₃³⁻–CO₃²⁻ complex reduces the energy barrier for the reduction of CO₃²⁻ at the cathode and for the liberation of O²⁻ that can be oxidized at a lower potential than CO₃²⁻ at the anode. Therefore, the electrolyte engineering is an effective strategy for designing high-temperature CO₂ electrolyzers with high CO₂ absorption and energy efficiency.

熔融碳酸盐电解池（MCEC）是一种很有前景的电化学CO ₂捕获和转化过程。然而，CO _{2吸收和能量效率受到缓慢的CO 2}吸收动力学和高电极过电势的限制。在此，我们提出了一种电解质工程策略来提高CO ₂吸收率并降低阳极和阴极的过电势。当BO ₃ ³⁻添加到熔融的Li ₂ CO ₃ -Na ₂ CO ₃ -K ₂ CO ₃中时，CO ₂^{在200 mA cm -2}下，吸附效率从3.3%提高到60%，阴极过电势降低约567 mV，阳极过电势降低约238 mV 。因此，在650℃时能量效率达到76.2%。_{CO 2}吸收和能量效率的提高归功于BO ₃ ³⁻改变了熔融碳酸盐的热力学性质，即BO ₃ ³⁻ –CO ₃ ^{2−络合物降低了CO} ₃ ²还原的能量势垒⁻在阴极释放 O ^{2− ，其可以在比 CO} ₃ ²⁻更低的电势下被氧化在阳极。因此，电解质工程是设计具有高CO ₂吸收和能源效率的高温CO ₂电解槽的有效策略。