Low-temperature enabled Li/Ni mixing in low Ni/Mn ratio Li-rich layered oxides as high performance electrodes

Cobalt-free lithium-rich layered oxides (LRLOs) are highly promising candidates for the next-generation high-energy-density positive electrodes. One of the key challenges is to achieve both superior electrochemical performance and structural stability. However, systematic studies on the effects of synthesis temperature on the performance of low Ni/Mn ratio LRLO electrodes are limited. Herein, we reveal a strong synergy between low synthesis temperature and low Ni/Mn ratio in enhancing electrochemical performance and structural robustness in a series of Co-free LRLOs. Our results demonstrate that synthesis temperature has a significant effect on the phase stability, cation ordering, and electrochemical behavior of low Ni/Mn ratio LRLOs. We further demonstrate that the low Ni/Mn ratio, together with low synthesis temperature, promotes Li/Ni mixing, which markedly alters the surface morphology and particle size. The low Ni/Mn ratio LRLO electrode synthesized at 700 °C with a Ni/Mn ratio of 1:4.5 delivers a high reversible specific capacity of 210 mAh g⁻¹ and achieves nearly 100 % capacity retention under both 1 C and 0.5C for 100 cycles. These findings provide new insights into the development of cost-effective, scalable, and high-performance Li-rich positive electrode materials.