Hierarchical SnO 2 -Encapsulated Porous Carbon Microspheres Derived by Dual Templated Method for Enhanced Lithium Storage Capacity

Tin-based materials have attracted much attention as a promising anode for lithium-ion batteries (LIBs) due to their high theoretical capacity towards lithium storage, but their commercial viability is hindered by severe volume expansion/contraction during battery operation. Porous carbon can act as an ideal buffer layer to solve this problem, but the rational design of porous tin-carbon composite anode materials with low cost remains a great challenge. Herein, we propose a unique synthetic strategy, involving rational usage of water-in-oil (W/O) phase separation and NaCl-template methods, to design new porous tin-carbon microspheres. These composite microspheres have an impressive surface area of 104[Formula: see text]m 2 g[Formula: see text] with a reasonable porosity size, and ultrafine SnO 2 nanocrystals ([Formula: see text]5[Formula: see text]nm) are uniformly dispersed into the carbon matrix. As-designed porous carbon not only mitigates the volume expansion of SnO 2 , but also provides a larger electrolyte/electrode contacting area for the lithium flux. Such unique structural features endow the SnO 2 -encapsulated porous carbon microsphere (SnO 2 @PCM) electrode with high discharge capacity (1184.4[Formula: see text]mA[Formula: see text]h g[Formula: see text] after 500 cycles at 2[Formula: see text]A[Formula: see text]g[Formula: see text]) and long operation life. Furthermore, a full cell consisting of as-prepared SnO 2 @PCM anode and LiFePO 4 cathode delivers an excellent capacity retention of 82.2% at 1[Formula: see text]A[Formula: see text]g[Formula: see text] after 200 cycles, demonstrating the successful practical application of this type of material. This work presents a feasible strategy for designing tin–carbon composites, which could be further generalized to develop other high-volume-change anode materials.