Lithium metal anodes have attracted much attention as candidates for high-energy batteries, but there have been few reports of long cycling behaviour, and the degradation mechanism of realistic high-energy Li metal cells remains unclear. Here, we develop a prototypical 300 Wh kg⁻¹ (1.0 Ah) pouch cell by integrating a Li metal anode, a LiNi_0.6Mn_0.2Co_0.2O₂ cathode and a compatible electrolyte. Under small uniform external pressure, the cell undergoes 200 cycles with 86% capacity retention and 83% energy retention. In the initial 50 cycles, flat Li foil converts into large Li particles that are entangled in the solid-electrolyte interphase, which leads to rapid volume expansion of the anode (cell thickening of 48%). As cycling continues, the external pressure helps the Li anode maintain good contact between the Li particles, which ensures a conducting percolation pathway for both ions and electrons, and thus the electrochemical reactions continue to occur. Accordingly, the solid Li particles evolve into a porous structure, which manifests in substantially reduced cell swelling by 19% in the subsequent 150 cycles.

锂金属阳极作为高能电池的候选者已经引起了广泛的关注，但是很少有关于长循环行为的报道，并且实际的高能锂金属电池的降解机理仍然不清楚。在这里，我们通过集成锂金属阳极，LiNi _0.6 Mn _0.2 Co _0.2 O _2来开发原型300 Wh kg ^-1（1.0 Ah）袋式电池阴极和兼容的电解质。在较小的均匀外部压力下，电池将经历200个循环，容量保持率达86％，能量保持率达83％。在最初的50个循环中，扁平的Li箔转换为大的Li颗粒，这些颗粒被缠结在固体电解质中间相中，从而导致阳极的体积迅速膨胀（电池增厚48％）。随着循环的继续，外部压力有助于Li阳极在Li颗粒之间保持良好的接触，从而确保了离子和电子的传导渗流途径，因此电化学反应继续发生。因此，固体Li颗粒演变成多孔结构，这表现为在随后的150个循环中电池溶胀显着降低了19％。