Highly compacted TiO/C micospheres via in-situ surface-confined intergrowth with ultra-long life for reversible Na-ion storage.

TiO as the promising anode material candidate of sodium-ion battery suffers from poor conductivity and slow ion diffusion rate, which severely hampers its development. Highly compacted TiO/C microspheres without inner pores/tunnels are synthesized by a very facile one-pot rapid processing method based on novel in-situ surface-confined inter-growth mechanism. This highly compacted TiO/C microspheres exhibit an excellent electrochemical performance of reversible Na storage despite with relatively large particle/aggregation size from submicrometer to micrometer. An outstanding cycling stability extending to 10,000 cycles is gained with a high retention capacity of 140.5 mAh g at a current rate of 2 A g. An ultra-high reversible capacity of 362 mAh g close to its theoretic specific capacity is obtained at a current rate of 0.05 A g. The successful combination of highly compacted structure with large particle size, excellent electrochemical performance as well as rapid cost-effective preparing process might provide a potential industrial approach for efficiently synthesizing electrode materials for Na ion batteries.