The mechanical stability of the solid electrolyte interphase (SEI) is independent of the charging rate, but can be effectively improved by properly designing geometric and material properties of anode components in the lithium ion battery.

To predict the cyclic stability of secondary battery electrodes, the mechanical behaviors of polymer binders and conductive composites (BCC) is of great significance. In terms of uniaxial tension, tensile stress relaxation, and bonding strength tests, the present study encompasses a systematic investigation of the mechanical properties of two typical aqueous binders with different contents of Super-S carbon black (SS) under a liquid electrolyte. Meanwhile, the microstructure of cured film and the surface morphology of the bonding interface are investigated in detail. When the weight ratio of SS increases from 0% to 50%, the cured BCC films manifest a higher ratio of tensile strength to modulus and a shorter characteristic relaxation time. Moreover, suitable loadings of SS can improve the tensile shear strength and remarkably reduce the percentage of interface failure of aqueous polymer-bonded Cu current collector. Nevertheless, an excess of carbon black amount cannot maintain its enhancing effect and can even impair the adhesive layer. Finally, a sodium alginate-based polymer composite holds much more superior mechanical properties than the mixture of sodium carboxymethyl cellulose and styrene-butadiene rubber at the same content of carbon black. Noticeably, the two kinds of aqueous polymer doped by 50 wt % of SS exhibit the best adhesive properties.

Porous silicon-based anode materials have gained much interest because the porous structure can effectively accommodate volume changes and release mechanical stress, leading to improved cycling performance. Magnesiothermic reduction has emerged as an effective way to convert silica into porous silicon with a good electrochemical performance. However, corrosive HF etching is normally a mandatory step to improve the electrochemical performance of the as-synthesized silicon, which significantly increases the safety risk. This has become one of the major issues that impedes practical application of the magnesiothermic reduction synthesis of the porous silicon anode. Here, a facile HF-free method is reported to synthesize macro-/mesoporous silicon with good cyclic and rate performance by simply increasing the reduction temperature from 700 °C to 800 °C and 900 °C. The mechanism for the structure change resulting from the increased temperature is elaborated. A finite element simulation indicated that the 3D continuous structure formed by the magnesiothermic reduction at 800 °C and 900 °C could undertake the mechanical stress effectively and was responsible for an improved cyclic stability compared to the silicon synthesized at 700 °C.