## 3 SiCN-Based Anode Materials
Their investigation into polyphenylvinyl silicon carbide amide-derived SiCN anodes revealed that heating to 1300 \({}^{\circ}\)C reduces hydrogen content, markedly decreasing voltage-capacity hysteresis. Concurrently, the ordering of free carbon at this temperature leads to lower specific capacity. However, elevated temperatures also improve charge transfer resistance and enhance SEI (solid electrolyte interface) stability through the ceramic matrix. Figure 8: Schematic illustration of the microstructure of amorphous SiCN ceramics derived from polysilazanes (**a**) and from polysilylcarbodimides (**b**). Copied with permission from Springer Nature [27]. Notably, the initial coulombic efficiency remains a significant challenge for carbon-rich SiCN anodes in lithium-ion batteries, showing little dependence on pyrolysis temperature. Similar to SiOC anodes, highly conductive materials such as carbon nanotubes (CNTs) [49; 50] and graphene [51] can be introduced into the SiCN matrix to improve its conductivity. Moreover, the addition of high-capacity materials like Si can further enhance the capacity. For instance, [PERSON] et al. [50] studied the electrochemical performance of multi-walled carbon nanotube-SiCN composite materials. Using a simple ultrasound-assisted method combined with high-temperature pyrolysis to synthesize the samples, the CNTs were evenly distributed within the SiCN ceramic matrix. This distribution maintained structural integrity during the polymer-to-ceramic transformation and formed a strong bond with the SiCN ceramic matrix. The resulting composite material showed superior rate performance compared to the original SiCN powder, CNTs, and graphite, achieving a capacity of 222.7 mAh\(\cdot\)g\({}^{-1}\) at a current density of 2000 mA g\({}^{-1}\). Additionally, [PERSON] et al. [23] found that boron could modify the nanostructure of SiCN, improving its chemical stability and electronic conductivity. Furthermore, the cycling stability of the battery increased as \"microporous activity\" improved, which aligns with previous studies on SiOC ceramics [52]. [PERSON] et al. found that it was recognized that increasing the porosity of SiCN negative electrode materials can improve the capacity and cycling performance of lithium-ion batteries. Therefore, a porous SiCN-HF electrode material was obtained by etching SiCN materials with HF aqueous solution. After conducting charge discharge cycling performance tests on it, it was found that compared to dense SiCN, its cycling stability was significantly improved. The principle is that it is easy for lithium-ions to be intercalated and detached after treatment, thereby alleviating the capacity attenuation caused by volume changes. A new type of material using porous SiCN-HF material as the negative electrode material for lithium batteries has been achieved [53]. Similarly, the laboratory subjected NaOH aqueous solution to the same etching treatment, and in the same charge discharge cycle performance test, compared to SiCN material, the discharge specific capacity and cycle stability were significantly improved. The principle is that the nano diameter pores formed after treatment facilitate the insertion and removal of lithium-ions [53]. [PERSON]'s team [49] synthesized a composite material of SiCN and graphite (SiCN-graphite) by pyrolyzing a mixture of amorphous SiCN derived from polysilicone ethylenediamine and graphite powder. The SiCN-graphite material, used as the negative electrode active material for lithium-ion batteries, demonstrates outstanding electrochemical performance. Following the same charge-discharge cycle test as in the previous experiment, the SiCN-C anode demonstrated high initial and stable specific discharge capacities. Under the same charging and discharging conditions, both values were significantly higher than those of pure polymer-derived SiCN and C. Additionally, the SiCN-C negative electrode demonstrates high-rate charge-discharge capability, meeting the standards for commercial negative electrode materials.