在(zai)电(dian)(dian)的(de)(de)传递(di)上(shang)，物质可以(yi)分(fen)(fen)为电(dian)(dian)的(de)(de)良导(dao)体(ti)、半导(dao)体(ti)和绝(jue)缘体(ti)三类。它们导(dao)电(dian)(dian)能力(li)(li)(li)的(de)(de)大小一般(ban)用电(dian)(dian)阻率(p)来表示(shi)。石墨(mo)晶(jing)体(ti)在(zai)层(ceng)面方向上(shang)碳原子之间(jian)的(de)(de)结(jie)合(he)是共价键叠合(he)金属键所以(yi)在(zai)石墨(mo)层(ceng)面方向有(you)良好的(de)(de)导(dao)电(dian)(dian)性(xing)，而在(zai)石墨(mo)晶(jing)体(ti)的(de)(de)层(ceng)与层(ceng)之间(jian)是由较弱的(de)(de)分(fen)(fen)子键连结(jie)所以(yi)导(dao)电(dian)(dian)能力(li)(li)(li)弱。因此，石墨(mo)化(hua)程度高(gao)的(de)(de)炭(tan)素材料的(de)(de)导(dao)电(dian)(dian)能力(li)(li)(li)有(you)明显的(de)(de)各向异(yi)性(xing)。

例如(ru)，天然鳞片石(shi)墨(mo)和热解(jie)石(shi)墨(mo)的(de)(de)(de)各向异(yi)性(xing)比可高达10^4。人造石(shi)墨(mo)制品的(de)(de)(de)电(dian)(dian)(dian)(dian)(dian)阻率各向异(yi)性(xing)比只有(you)1.2~1.4.各种(zhong)炭(tan)素(su)材料(liao)的(de)(de)(de)导(dao)电(dian)(dian)(dian)(dian)(dian)能(neng)力是不(bu)同(tong)的(de)(de)(de)，石(shi)墨(mo)化度高，层面排列(lie)近于平行，晶体缺(que)陷少，有(you)利于自由电(dian)(dian)(dian)(dian)(dian)子(zi)流动,所以电(dian)(dian)(dian)(dian)(dian)阻率就低。一(yi)些常(chang)用炭(tan)素(su)材料(liao)的(de)(de)(de)电(dian)(dian)(dian)(dian)(dian)阻率列(lie)于表1-9.炭(tan)素(su)阳极(ji)作为铝电(dian)(dian)(dian)(dian)(dian)解(jie)的(de)(de)(de)导(dao)电(dian)(dian)(dian)(dian)(dian)材料(liao)，要求(qiu)具有(you)良好(hao)的(de)(de)(de)导(dao)电(dian)(dian)(dian)(dian)(dian)性(xing)、较(jiao)低的(de)(de)(de)电(dian)(dian)(dian)(dian)(dian)阻率，以减少阳极(ji)的(de)(de)(de)申耗，提(ti)高铝电(dian)(dian)(dian)(dian)(dian)解(jie)的(de)(de)(de)电(dian)(dian)(dian)(dian)(dian)流效率。电(dian)(dian)(dian)(dian)(dian)阻率与煅(duan)后焦的(de)(de)(de)煅(duan)烧(shao)程度、阳极(ji)的(de)(de)(de)体积(ji)密(mi)度及焙烧(shao)温度有(you)直(zhi)接的(de)(de)(de)关系。

炭(tan)素(su)材料导电(dian)(dian)(dian)性(xing)随温(wen)(wen)(wen)度的(de)(de)变化受两(liang)方(fang)面因素(su)的(de)(de)制(zhi)约(yue)。一方(fang)面石(shi)墨晶体受热时(shi)，在(zai)价(jia)带上的(de)(de)电(dian)(dian)(dian)子激(ji)发跃迁(qian)到导带上,成为(wei)自由电(dian)(dian)(dian)子,自由电(dian)(dian)(dian)子的(de)(de)数量增(zeng)(zeng)多(duo),电(dian)(dian)(dian)阻(zu)率减小;另一方(fang)面,温(wen)(wen)(wen)度升高(gao)时(shi)，晶格点阵(zhen)的(de)(de)热振动加剧，振幅增(zeng)(zeng)大，自由电(dian)(dian)(dian)子的(de)(de)流(liu)动阻(zu)力加大，电(dian)(dian)(dian)阻(zu)率增(zeng)(zeng)加。所以，当温(wen)(wen)(wen)度使电(dian)(dian)(dian)子激(ji)发作用起(qi)主导时(shi),炭(tan)素(su)材料的(de)(de)电(dian)(dian)(dian)阻(zu)温(wen)(wen)(wen)度系(xi)数为(wei)负(fu)(fu)值(zhi)(zhi)，而当晶格热振动起(qi)主导作用时(shi),电(dian)(dian)(dian)阻(zu)温(wen)(wen)(wen)度系(xi)数为(wei)正值(zhi)(zhi)。石(shi)墨的(de)(de)电(dian)(dian)(dian)阻(zu)温(wen)(wen)(wen)度系(xi)数在(zai)100~900K以下时(shi)为(wei)负(fu)(fu)值(zhi)(zhi)，而在(zai)900 K 以上时(shi)为(wei)正值(zhi)(zhi)。