本發明(ming)屬于(yu)新能源材(cai)料制(zhi)備,涉(she)及一種高導電率錳摻(chan)雜磷(lin)酸鐵(tie)鋰正極(ji)材(cai)料的制(zhi)備方法。
背景技術:
1、磷(lin)(lin)酸鐵(tie)(tie)(tie)鋰(lifepo4)作為(wei)鋰離(li)子電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)的(de)(de)(de)正極材料具有(you)多項優勢。第(di)(di)一,安全(quan)性(xing)(xing)(xing)(xing)(xing)高(gao)(gao)(gao),磷(lin)(lin)酸鐵(tie)(tie)(tie)鋰具有(you)較(jiao)高(gao)(gao)(gao)的(de)(de)(de)熱穩(wen)(wen)定(ding)(ding)性(xing)(xing)(xing)(xing)(xing)和化學(xue)穩(wen)(wen)定(ding)(ding)性(xing)(xing)(xing)(xing)(xing),相對于(yu)(yu)一些其(qi)他正極材料,如鈷酸鋰,它(ta)的(de)(de)(de)熱失控(kong)風(feng)險較(jiao)低(di)(di),從(cong)而提高(gao)(gao)(gao)了(le)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)的(de)(de)(de)安全(quan)性(xing)(xing)(xing)(xing)(xing)。第(di)(di)二,穩(wen)(wen)定(ding)(ding)的(de)(de)(de)循環(huan)性(xing)(xing)(xing)(xing)(xing)能(neng)(neng),磷(lin)(lin)酸鐵(tie)(tie)(tie)鋰電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)具有(you)良好(hao)的(de)(de)(de)循環(huan)壽命,表現(xian)出較(jiao)高(gao)(gao)(gao)的(de)(de)(de)充放(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)循環(huan)穩(wen)(wen)定(ding)(ding)性(xing)(xing)(xing)(xing)(xing),能(neng)(neng)夠保(bao)(bao)持相對較(jiao)長時(shi)間的(de)(de)(de)高(gao)(gao)(gao)性(xing)(xing)(xing)(xing)(xing)能(neng)(neng)。第(di)(di)三,高(gao)(gao)(gao)放(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)平(ping)臺電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓,磷(lin)(lin)酸鐵(tie)(tie)(tie)鋰電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)的(de)(de)(de)放(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)平(ping)臺電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓相對較(jiao)高(gao)(gao)(gao),約3.2v,這有(you)助于(yu)(yu)提高(gao)(gao)(gao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)的(de)(de)(de)能(neng)(neng)量密度(du)和功率(lv)(lv)密度(du)。第(di)(di)四,低(di)(di)自放(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)率(lv)(lv),磷(lin)(lin)酸鐵(tie)(tie)(tie)鋰電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)的(de)(de)(de)自放(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)率(lv)(lv)相對較(jiao)低(di)(di),即(ji)使(shi)(shi)在長時(shi)間不使(shi)(shi)用(yong)的(de)(de)(de)情況(kuang)下(xia),電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)仍(reng)能(neng)(neng)保(bao)(bao)持相對較(jiao)高(gao)(gao)(gao)的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)荷。第(di)(di)五(wu),環(huan)保(bao)(bao)性(xing)(xing)(xing)(xing)(xing),磷(lin)(lin)酸鐵(tie)(tie)(tie)鋰是相對環(huan)保(bao)(bao)的(de)(de)(de)材料,其(qi)中(zhong)(zhong)不含稀有(you)金屬和有(you)毒重金屬,有(you)助于(yu)(yu)降低(di)(di)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)制(zhi)造和處(chu)理的(de)(de)(de)環(huan)境(jing)影(ying)響。因此,磷(lin)(lin)酸鐵(tie)(tie)(tie)鋰電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)被廣泛(fan)應(ying)用(yong)于(yu)(yu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)動汽車(che)、電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)動自行車(che)、儲能(neng)(neng)系統(tong)等領域,其(qi)安全(quan)性(xing)(xing)(xing)(xing)(xing)、穩(wen)(wen)定(ding)(ding)性(xing)(xing)(xing)(xing)(xing)和相對低(di)(di)成本使(shi)(shi)得它(ta)成為(wei)鋰離(li)子電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)市(shi)場中(zhong)(zhong)的(de)(de)(de)重要選(xuan)擇之一。然而,磷(lin)(lin)酸鐵(tie)(tie)(tie)鋰的(de)(de)(de)導電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)率(lv)(lv)和高(gao)(gao)(gao)溫性(xing)(xing)(xing)(xing)(xing)能(neng)(neng)欠缺。因此,開發錳(meng)摻雜(za)的(de)(de)(de)磷(lin)(lin)酸鐵(tie)(tie)(tie)鋰,即(ji)將錳(meng)(mn)元素引入磷(lin)(lin)酸鐵(tie)(tie)(tie)鋰晶(jing)格結構(gou)中(zhong)(zhong),可以(yi)改善磷(lin)(lin)酸鐵(tie)(tie)(tie)鋰的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)導率(lv)(lv),有(you)助于(yu)(yu)減(jian)少電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)內阻,從(cong)而提高(gao)(gao)(gao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)的(de)(de)(de)放(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)性(xing)(xing)(xing)(xing)(xing)能(neng)(neng)和充電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)速率(lv)(lv)。錳(meng)摻雜(za)還可以(yi)提高(gao)(gao)(gao)磷(lin)(lin)酸鐵(tie)(tie)(tie)鋰電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)的(de)(de)(de)高(gao)(gao)(gao)溫性(xing)(xing)(xing)(xing)(xing)能(neng)(neng),降低(di)(di)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)在高(gao)(gao)(gao)溫環(huan)境(jing)下(xia)的(de)(de)(de)衰減(jian)速率(lv)(lv)。
2、一(yi)些有關錳(meng)摻雜(za)(za)(za)磷(lin)(lin)酸(suan)(suan)鐵(tie)鋰(li)材(cai)料(liao)(liao)(liao)(liao)制(zhi)(zhi)備(bei)(bei)(bei)方(fang)法(fa)的(de)(de)發(fa)明專(zhuan)利(li)已經(jing)公開(kai),例如,一(yi)種球狀錳(meng)摻雜(za)(za)(za)磷(lin)(lin)酸(suan)(suan)鐵(tie)鋰(li)微納(na)米材(cai)料(liao)(liao)(liao)(liao)的(de)(de)制(zhi)(zhi)備(bei)(bei)(bei)方(fang)法(fa)(zl201310089080.8),一(yi)種金屬表面包(bao)覆na摻雜(za)(za)(za)磷(lin)(lin)酸(suan)(suan)鐵(tie)鋰(li)復(fu)合正(zheng)極(ji)材(cai)料(liao)(liao)(liao)(liao)的(de)(de)制(zhi)(zhi)備(bei)(bei)(bei)方(fang)法(fa)(zl201310289531.2),一(yi)種團簇狀錳(meng)摻雜(za)(za)(za)磷(lin)(lin)酸(suan)(suan)鐵(tie)鋰(li)電極(ji)材(cai)料(liao)(liao)(liao)(liao)及(ji)其制(zhi)(zhi)備(bei)(bei)(bei)方(fang)法(fa)(zl201810492266.0),一(yi)種氧化鋁(lv)包(bao)覆錳(meng)摻雜(za)(za)(za)磷(lin)(lin)酸(suan)(suan)鐵(tie)鋰(li)正(zheng)極(ji)材(cai)料(liao)(liao)(liao)(liao)的(de)(de)制(zhi)(zhi)備(bei)(bei)(bei)方(fang)法(fa)(zl201811247044.9),錳(meng)摻雜(za)(za)(za)磷(lin)(lin)酸(suan)(suan)鐵(tie)鋰(li)電極(ji)材(cai)料(liao)(liao)(liao)(liao)的(de)(de)制(zhi)(zhi)備(bei)(bei)(bei)方(fang)法(fa)(zl201810186951.0),一(yi)種具備(bei)(bei)(bei)高導電性的(de)(de)鉀錳(meng)摻雜(za)(za)(za)磷(lin)(lin)酸(suan)(suan)鐵(tie)鋰(li)復(fu)合正(zheng)極(ji)材(cai)料(liao)(liao)(liao)(liao)的(de)(de)制(zhi)(zhi)備(bei)(bei)(bei)方(fang)法(fa)(zl201310289533.1)等。這些專(zhuan)利(li)的(de)(de)材(cai)料(liao)(liao)(liao)(liao)制(zhi)(zhi)備(bei)(bei)(bei)過程一(yi)般是多步,方(fang)法(fa)復(fu)雜(za)(za)(za),增加了材(cai)料(liao)(liao)(liao)(liao)成本(ben)。
3、一種磷酸錳鐵(tie)鋰(li)(li)正(zheng)極(ji)材(cai)(cai)料的制(zhi)備(bei)方法(cn202111198875.3)公開了(le)按(an)(an)照(zhao)摩爾比(bi)7:3稱(cheng)取一定量(liang)(liang)的錳源(yuan)和(he)鐵(tie)源(yuan),再按(an)(an)照(zhao)一定化學計量(liang)(liang)比(bi)稱(cheng)取鋰(li)(li)源(yuan)、磷源(yuan)、碳源(yuan)、摻雜劑(ji),加(jia)(jia)入純水,經球(qiu)磨(mo)和(he)砂磨(mo)后(hou),得(de)(de)到(dao)(dao)棕色的前(qian)(qian)驅(qu)體粉末。將(jiang)前(qian)(qian)驅(qu)體放(fang)在氮氣氣氛保護下(xia)燒結(jie)。一種磷酸錳鐵(tie)鋰(li)(li)正(zheng)極(ji)材(cai)(cai)料及其制(zhi)備(bei)方法與應(ying)用(cn202380008749.8)公開了(le)將(jiang)鋰(li)(li)源(yuan)、鐵(tie)源(yuan)、錳源(yuan)、磷源(yuan)、碳源(yuan)、乳化劑(ji)進(jin)行(xing)(xing)球(qiu)磨(mo),所(suo)(suo)得(de)(de)漿料a經干燥(zao)、研磨(mo)、煅燒、球(qiu)磨(mo)后(hou),得(de)(de)到(dao)(dao)大粒(li)徑前(qian)(qian)驅(qu)體和(he)小粒(li)徑前(qian)(qian)驅(qu)體;然(ran)后(hou)將(jiang)小粒(li)徑前(qian)(qian)驅(qu)體加(jia)(jia)入淀粉懸濁液(ye)中(zhong),超聲分散后(hou),加(jia)(jia)入交聯劑(ji),加(jia)(jia)熱攪拌反應(ying),所(suo)(suo)得(de)(de)膠體混合(he)物(wu)經干燥(zao)、球(qiu)磨(mo),得(de)(de)到(dao)(dao)材(cai)(cai)料c;最后(hou)將(jiang)大粒(li)徑前(qian)(qian)驅(qu)體和(he)材(cai)(cai)料c混合(he),所(suo)(suo)得(de)(de)混合(he)物(wu)在保護氣體下(xia)進(jin)行(xing)(xing)煅燒,得(de)(de)到(dao)(dao)磷酸錳鐵(tie)鋰(li)(li)正(zheng)極(ji)材(cai)(cai)料。
技術實現思路
1、本發明(ming)的目的在于提供一種制(zhi)(zhi)備方(fang)法簡單,錳摻雜磷酸(suan)鐵(tie)鋰(li)正(zheng)極材料充(chong)放電性能好的高導(dao)電率錳摻雜磷酸(suan)鐵(tie)鋰(li)正(zheng)極材料的制(zhi)(zhi)備方(fang)法。
2、鑒于此(ci),本發明采用(yong)的技術方(fang)案是:一種高(gao)導電率(lv)錳摻雜(za)磷酸鐵鋰(li)正極材料的制備方(fang)法,包括以下步驟:1)將(jiang)磷源(yuan)(yuan)、鐵源(yuan)(yuan)、鋰(li)源(yuan)(yuan)、錳源(yuan)(yuan)和還原(yuan)劑共(gong)同(tong)放入(ru)球(qiu)磨罐進行球(qiu)磨處(chu)理,處(chu)理后獲(huo)得錳摻雜(za)磷酸鐵鋰(li)前(qian)驅體(ti);(2)將(jiang)前(qian)驅體(ti)在惰性氣體(ti)中燒結,降(jiang)溫后獲(huo)得高(gao)導電錳摻雜(za)磷酸鐵鋰(li)正極材料。
3、進一步(bu),方案中所述磷(lin)(lin)源(yuan)選自(zi)磷(lin)(lin)酸(suan)二(er)氫鉀、磷(lin)(lin)酸(suan)鐵銨(an)、磷(lin)(lin)酸(suan)二(er)氫銨(an)中的一種或多種,優選磷(lin)(lin)酸(suan)二(er)氫銨(an)。
4、進一步,方案(an)中所述鐵(tie)(tie)源選自(zi)硫(liu)酸(suan)亞鐵(tie)(tie)、硝酸(suan)鐵(tie)(tie)、三氧化二鐵(tie)(tie)中的一種或多(duo)種,優選三氧化二鐵(tie)(tie)。
5、進一步,方案(an)中(zhong)所述鋰(li)源(yuan)選自(zi)碳(tan)酸鋰(li)、氫氧(yang)化(hua)鋰(li)、磷酸二(er)氫鋰(li)中(zhong)的一種或多種,優選碳(tan)酸鋰(li)。
6、進一步,方(fang)案(an)中所述錳(meng)(meng)源選(xuan)自碳酸錳(meng)(meng)、氧化錳(meng)(meng)、氯(lv)化錳(meng)(meng)、硝酸錳(meng)(meng)中的一種(zhong)或多種(zhong),優選(xuan)碳酸錳(meng)(meng)。
7、進一(yi)步,方案中(zhong)所述還原(yuan)劑選(xuan)自碳(tan)粉(fen)、石墨烯粉(fen)、碳(tan)納米管粉(fen)、抗(kang)壞血(xue)酸、葡(pu)萄(tao)糖(tang)、蔗糖(tang)中(zhong)的一(yi)種(zhong)或(huo)多種(zhong),優選(xuan)蔗糖(tang)
8、進一步,所述(shu)(shu)磷源:鐵源:鋰(li)源:還原(yuan)劑的質量比為(wei)1:0.55~0.6:0.26~0.28:0.75;所述(shu)(shu)鋰(li)源:錳源的質量比為(wei)1:0.06~0.2。
9、進一步,上述方案中所述球磨處理時,球磨缸內球體的填充(chong)率(lv)在50%到70%,球磨時間(jian)2到10小時,轉速(su)300rpm到800rpm,球磨介(jie)質使(shi)用(yong)無水乙醇。
10、進一步,上述(shu)方案中所述(shu)惰性氣體為氮(dan)氣或者氬氣,燒(shao)結參數如下(xia):升溫速(su)率2到(dao)10℃/min,燒(shao)結溫度400℃到(dao)900℃,燒(shao)結時(shi)(shi)間(jian)4小時(shi)(shi)到(dao)10小時(shi)(shi)。
11、本發明還提(ti)供了一(yi)種高導電率錳(meng)摻雜磷酸鐵鋰正極(ji)材(cai)料,由上述的方(fang)法制(zhi)備得到,其分子式為(wei)limn0.02fe0.98po4/c或(huo)(huo)limn0.04fe0.96po4/c或(huo)(huo)limn0.06fe0.94po4/c。
12、與現(xian)有技術相比,本發明具有以(yi)下有益效果:
13、優(you)點:第一,制備方法(fa)簡單,一步(bu)(bu)法(fa)制備前驅體材料(liao)(liao)(liao);步(bu)(bu)驟少,僅(jin)通(tong)過球(qiu)(qiu)磨(mo)和燒結兩(liang)個主要步(bu)(bu)驟就(jiu)可得到磷(lin)酸(suan)鐵錳鋰材料(liao)(liao)(liao),得到的材料(liao)(liao)(liao)相較于(yu)磷(lin)酸(suan)鐵鋰也能達到電池(chi)容(rong)量的提高效(xiao)果(guo)。第二,本發明制備的正極材料(liao)(liao)(liao)均(jun)一性(xing)高,充放電性(xing)能好。第三,無(wu)水乙醇(chun)(chun)作為非(fei)極性(xing)溶劑,與(yu)材料(liao)(liao)(liao)的反應活性(xing)較低,有(you)助于(yu)減少副反應;具(ju)有(you)較好的潤濕(shi)性(xing)和分散(san)性(xing),能夠更(geng)好地將(jiang)粉末(mo)顆粒均(jun)勻(yun)混合,提高球(qiu)(qiu)磨(mo)效(xiao)果(guo),有(you)助于(yu)促進材料(liao)(liao)(liao)之間(jian)的摻雜(za),減少硬團聚的形成(cheng);無(wu)水乙醇(chun)(chun)具(ju)有(you)較低的沸(fei)點,更(geng)容(rong)易(yi)通(tong)過加熱等方式(shi)從混合物中去除(chu)。
1.一種高(gao)導電率錳摻(chan)雜(za)磷酸(suan)(suan)鐵(tie)鋰(li)(li)正極材(cai)料(liao)的制備方法,其特征在(zai)(zai)于,包括(kuo)以下步驟:1)將磷源(yuan)、鐵(tie)源(yuan)、鋰(li)(li)源(yuan)、錳源(yuan)和還原(yuan)劑共同放入(ru)球磨(mo)罐進(jin)行(xing)球磨(mo)處(chu)理,處(chu)理后獲得(de)錳摻(chan)雜(za)磷酸(suan)(suan)鐵(tie)鋰(li)(li)前驅體(ti);(2)將前驅體(ti)在(zai)(zai)惰性氣體(ti)中燒結,降溫后獲得(de)高(gao)導電錳摻(chan)雜(za)磷酸(suan)(suan)鐵(tie)鋰(li)(li)正極材(cai)料(liao)。
2.根(gen)據權利(li)要(yao)求(qiu)1所述一種(zhong)(zhong)高導電(dian)率(lv)錳摻(chan)雜磷(lin)(lin)(lin)酸(suan)(suan)鐵鋰正極材料(liao)的制備方法,其特征在于:所述磷(lin)(lin)(lin)源(yuan)選(xuan)自磷(lin)(lin)(lin)酸(suan)(suan)二氫鉀、磷(lin)(lin)(lin)酸(suan)(suan)鐵銨、磷(lin)(lin)(lin)酸(suan)(suan)二氫銨中的一種(zhong)(zhong)或多(duo)種(zhong)(zhong)。
3.根據(ju)權利要求1所述一(yi)種(zhong)高導電率錳摻雜磷酸鐵(tie)鋰正極(ji)材料的制備方法,其特征在(zai)于(yu):所述鐵(tie)源選自硫酸亞鐵(tie)、硝酸鐵(tie)、三氧化二鐵(tie)中(zhong)的一(yi)種(zhong)或多種(zhong)。
4.根(gen)據權利要求1所述一種(zhong)高導電(dian)率錳摻雜磷(lin)(lin)酸(suan)鐵鋰(li)正極材料(liao)的(de)制(zhi)備方法,其(qi)特征在于:所述鋰(li)源(yuan)選自碳酸(suan)鋰(li)、氫氧化鋰(li)、磷(lin)(lin)酸(suan)二氫鋰(li)中的(de)一種(zhong)或(huo)多種(zhong)。
5.根據權(quan)利要(yao)求1所述一(yi)種高導電率錳(meng)摻(chan)雜磷酸(suan)鐵(tie)鋰(li)正極材料的制(zhi)備(bei)方(fang)法,其特征(zheng)在于:所述錳(meng)源選自(zi)碳酸(suan)錳(meng)、氧化錳(meng)、氯化錳(meng)、硝(xiao)酸(suan)錳(meng)中的一(yi)種或多(duo)種。
6.根據權(quan)利要求1所述(shu)一(yi)種高導(dao)電率(lv)錳摻雜磷酸(suan)鐵(tie)鋰正極材料的(de)制備方法,其特征在于:所述(shu)還原劑選自碳粉(fen)、石(shi)墨烯(xi)粉(fen)、碳納米管粉(fen)、抗壞血酸(suan)、葡萄(tao)糖(tang)、蔗糖(tang)中(zhong)的(de)一(yi)種或多種。
7.根據權利要求(qiu)1-6任一項(xiang)所(suo)述一種(zhong)高(gao)導電率錳(meng)摻雜磷(lin)酸鐵鋰正極材料的(de)制備方法,其(qi)特征在于:所(suo)述磷(lin)源(yuan):鐵源(yuan):鋰源(yuan):還(huan)原劑的(de)質量比(bi)為(wei)1:0.55~0.6:0.26~0.28:0.75;所(suo)述鋰源(yuan):錳(meng)源(yuan)的(de)質量比(bi)為(wei)1:0.06~0.2。
8.根據權利要求1所述(shu)一種高導(dao)電(dian)率錳(meng)摻雜磷酸鐵鋰正(zheng)極(ji)材料的(de)(de)制備(bei)方法,其(qi)特征在于:所述(shu)球(qiu)磨處理時(shi),球(qiu)磨缸內球(qiu)體(ti)的(de)(de)填充率在50%到70%,球(qiu)磨時(shi)間2到10小時(shi),轉速300rpm到800rpm,球(qiu)磨介質使(shi)用無水(shui)乙(yi)醇(chun)。
9.根據(ju)權利要求1所(suo)述(shu)一種高導電率(lv)錳摻(chan)雜(za)磷酸鐵鋰正極材料的(de)制備(bei)方法,其特征在于:所(suo)述(shu)惰性氣(qi)體為氮(dan)氣(qi)或(huo)者氬氣(qi),燒(shao)結(jie)參(can)數如(ru)下(xia):升溫速率(lv)2到10℃/min,燒(shao)結(jie)溫度400℃到900℃,燒(shao)結(jie)時(shi)間4小時(shi)到10小時(shi)。
10.一種高導電(dian)率錳摻(chan)雜磷酸(suan)鐵鋰正(zheng)極材料,其(qi)特征在于:由權利要求1-9任一項所述的方法制備(bei)得到(dao),其(qi)分子式為limn0.02fe0.98po4/c或limn0.04fe0.96po4/c或limn0.06fe0.94po4/c。