Zhang Weidong, Wu Qiang, Huang Jinxin, Fan Lei, Shen Zeyu, He Yi, Feng Qi, Zhu Guannan, Lu Yingying
College of Chemical and Biological Engineering, State Key Laboratory of Chemical Engineering, Institute of Pharmaceutical Engineering, Zhejiang University, Hangzhou, 310027, China.
SAIC Motor Corporation, Shanghai, 201804, China.
Adv Mater. 2020 Jun;32(24):e2001740. doi: 10.1002/adma.202001740. Epub 2020 May 11.
The low Coulombic efficiency of the lithium metal anode is recognized as the real bottleneck to practical high-efficiency lithium metal batteries with limited Li excess. The grain size and microstructure of deposited lithium strongly influences the lithium plating/stripping efficiency. Here, a solubilizer-mediated carbonate electrolyte that can realize grain coarsening of lithium deposits (>20 µm in width) with oriented columnar morphology, which is in sharp contrast with conventional nanoscale dendrite-like lithium deposits in carbonate electrolytes, is reported. It exhibits improved Li Coulombic efficiency to 98.14% at a high capacity of 3 mAh cm over 150 cycles, because the colossal lithium deposition with minimal tortuosity can maintain the bulk Li with continuous electron conducting pathway during the stripping process, thus enabling efficient Li utilization. Li/NMC811 full batteries, composed of thin Li anode (45 µm) and a high-capacity NMC811 cathode (16.7 mg cm ), can achieve at least 12 times longer lifespan (200 cycles).
锂金属负极的低库仑效率被认为是实际应用中具有有限过量锂的高效锂金属电池的真正瓶颈。沉积锂的晶粒尺寸和微观结构强烈影响锂的沉积/剥离效率。在此，报道了一种增溶剂介导的碳酸盐电解质，它可以实现锂沉积物的晶粒粗化（宽度>20 µm），具有定向柱状形态，这与碳酸盐电解质中传统的纳米级树枝状锂沉积物形成鲜明对比。在150次循环中，在3 mAh cm的高容量下，其锂库仑效率提高到98.14%，因为巨大的锂沉积具有最小的曲折度，可以在剥离过程中通过连续的电子传导途径维持块状锂，从而实现锂的高效利用。由薄锂负极（45 µm）和高容量NMC811正极（16.7 mg cm）组成的Li/NMC811全电池可以实现至少12倍的更长寿命（200次循环）。
