Triggering anionic redox reaction (ARR) in layered oxide cathodes has emerged as an effective approach to overcoming the energy density limitations of conventional sodium-ion batteries (SIBs) solely based on cationic redox. However, the local structural deterioration and lattice oxygen loss associated with ARR remain challenging and unsolved, resulting in severe capacity and voltage decay. To address these issues, we herein present a lattice-strengthened P2-Na_0.66Ca_0.03[Li_0.24Mn_0.76]O₂ (NCLMO) cathode. The introduction of Ca into the Na layers enables the compressed TMO₂ slabs and reinforced TM–O bonds (TM = Li/Mn). Moreover, the incorporation of Ca into the Na layers effectively mitigates the out-of-plane migration of Li and impedes the in-plane migration of Mn during the anionic redox. The reduction of ion migration reduces the variation of the local environment surrounding O and hinders the formation of TM vacancy clusters, significantly mitigating the loss of lattice oxygen. Consequently, NCLMO delivers an impressive capacity retention of 76.04% at 1 C after 200 cycles. Our findings highlight the significance of maintaining local structural stability and offer novel insights towards achieving highly reversible ARR in layered oxide cathodes for high-energy SIBs.

中文翻译：

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晶格强化可在钠离子电池中实现可逆阴离子氧化还原化学


在层状氧化物阴极中触发阴离子氧化还原反应 （ARR） 已成为克服仅基于阳离子氧化还原的传统钠离子电池 （SIB） 能量密度限制的有效方法。然而，与 ARR 相关的局部结构恶化和晶格氧损失仍然具有挑战性且未解决，导致严重的容量和电压衰减。为了解决这些问题，我们在此提出了一种晶格强化 P2-Na_0.66Ca_0.03[Li_0.24Mn_0.76]O₂ （NCLMO） 阴极。将 Ca 引入 Na 层可以形成压缩的 TMO₂ 板和增强的 TM-O 键 （TM = Li/Mn）。此外，Ca 掺入 Na 层可有效减轻 Li 的面外迁移，并阻止阴离子氧化还原过程中 Mn 的面内迁移。离子迁移的减少减少了 O 周围局部环境的变化，并阻碍了 TM 空位簇的形成，从而显着减轻了晶格氧的损失。因此，NCLMO 在 200 次循环后在 1 C 下可提供 76.04% 的令人印象深刻的容量保持率。我们的研究结果强调了保持局部结构稳定性的重要性，并为在高能 SIB 的层状氧化物阴极中实现高度可逆的 ARR 提供了新的见解。